LCOV - code coverage report
Current view: top level - include/linux - xarray.h (source / functions) Hit Total Coverage
Test: landlock.info Lines: 110 176 62.5 %
Date: 2021-04-22 12:43:58 Functions: 12 16 75.0 %

          Line data    Source code
       1             : /* SPDX-License-Identifier: GPL-2.0+ */
       2             : #ifndef _LINUX_XARRAY_H
       3             : #define _LINUX_XARRAY_H
       4             : /*
       5             :  * eXtensible Arrays
       6             :  * Copyright (c) 2017 Microsoft Corporation
       7             :  * Author: Matthew Wilcox <willy@infradead.org>
       8             :  *
       9             :  * See Documentation/core-api/xarray.rst for how to use the XArray.
      10             :  */
      11             : 
      12             : #include <linux/bug.h>
      13             : #include <linux/compiler.h>
      14             : #include <linux/gfp.h>
      15             : #include <linux/kconfig.h>
      16             : #include <linux/kernel.h>
      17             : #include <linux/rcupdate.h>
      18             : #include <linux/spinlock.h>
      19             : #include <linux/types.h>
      20             : 
      21             : /*
      22             :  * The bottom two bits of the entry determine how the XArray interprets
      23             :  * the contents:
      24             :  *
      25             :  * 00: Pointer entry
      26             :  * 10: Internal entry
      27             :  * x1: Value entry or tagged pointer
      28             :  *
      29             :  * Attempting to store internal entries in the XArray is a bug.
      30             :  *
      31             :  * Most internal entries are pointers to the next node in the tree.
      32             :  * The following internal entries have a special meaning:
      33             :  *
      34             :  * 0-62: Sibling entries
      35             :  * 256: Retry entry
      36             :  * 257: Zero entry
      37             :  *
      38             :  * Errors are also represented as internal entries, but use the negative
      39             :  * space (-4094 to -2).  They're never stored in the slots array; only
      40             :  * returned by the normal API.
      41             :  */
      42             : 
      43             : #define BITS_PER_XA_VALUE       (BITS_PER_LONG - 1)
      44             : 
      45             : /**
      46             :  * xa_mk_value() - Create an XArray entry from an integer.
      47             :  * @v: Value to store in XArray.
      48             :  *
      49             :  * Context: Any context.
      50             :  * Return: An entry suitable for storing in the XArray.
      51             :  */
      52         457 : static inline void *xa_mk_value(unsigned long v)
      53             : {
      54         457 :         WARN_ON((long)v < 0);
      55         457 :         return (void *)((v << 1) | 1);
      56             : }
      57             : 
      58             : /**
      59             :  * xa_to_value() - Get value stored in an XArray entry.
      60             :  * @entry: XArray entry.
      61             :  *
      62             :  * Context: Any context.
      63             :  * Return: The value stored in the XArray entry.
      64             :  */
      65         442 : static inline unsigned long xa_to_value(const void *entry)
      66             : {
      67         442 :         return (unsigned long)entry >> 1;
      68             : }
      69             : 
      70             : /**
      71             :  * xa_is_value() - Determine if an entry is a value.
      72             :  * @entry: XArray entry.
      73             :  *
      74             :  * Context: Any context.
      75             :  * Return: True if the entry is a value, false if it is a pointer.
      76             :  */
      77       94391 : static inline bool xa_is_value(const void *entry)
      78             : {
      79       94391 :         return (unsigned long)entry & 1;
      80             : }
      81             : 
      82             : /**
      83             :  * xa_tag_pointer() - Create an XArray entry for a tagged pointer.
      84             :  * @p: Plain pointer.
      85             :  * @tag: Tag value (0, 1 or 3).
      86             :  *
      87             :  * If the user of the XArray prefers, they can tag their pointers instead
      88             :  * of storing value entries.  Three tags are available (0, 1 and 3).
      89             :  * These are distinct from the xa_mark_t as they are not replicated up
      90             :  * through the array and cannot be searched for.
      91             :  *
      92             :  * Context: Any context.
      93             :  * Return: An XArray entry.
      94             :  */
      95             : static inline void *xa_tag_pointer(void *p, unsigned long tag)
      96             : {
      97             :         return (void *)((unsigned long)p | tag);
      98             : }
      99             : 
     100             : /**
     101             :  * xa_untag_pointer() - Turn an XArray entry into a plain pointer.
     102             :  * @entry: XArray entry.
     103             :  *
     104             :  * If you have stored a tagged pointer in the XArray, call this function
     105             :  * to get the untagged version of the pointer.
     106             :  *
     107             :  * Context: Any context.
     108             :  * Return: A pointer.
     109             :  */
     110             : static inline void *xa_untag_pointer(void *entry)
     111             : {
     112             :         return (void *)((unsigned long)entry & ~3UL);
     113             : }
     114             : 
     115             : /**
     116             :  * xa_pointer_tag() - Get the tag stored in an XArray entry.
     117             :  * @entry: XArray entry.
     118             :  *
     119             :  * If you have stored a tagged pointer in the XArray, call this function
     120             :  * to get the tag of that pointer.
     121             :  *
     122             :  * Context: Any context.
     123             :  * Return: A tag.
     124             :  */
     125             : static inline unsigned int xa_pointer_tag(void *entry)
     126             : {
     127             :         return (unsigned long)entry & 3UL;
     128             : }
     129             : 
     130             : /*
     131             :  * xa_mk_internal() - Create an internal entry.
     132             :  * @v: Value to turn into an internal entry.
     133             :  *
     134             :  * Internal entries are used for a number of purposes.  Entries 0-255 are
     135             :  * used for sibling entries (only 0-62 are used by the current code).  256
     136             :  * is used for the retry entry.  257 is used for the reserved / zero entry.
     137             :  * Negative internal entries are used to represent errnos.  Node pointers
     138             :  * are also tagged as internal entries in some situations.
     139             :  *
     140             :  * Context: Any context.
     141             :  * Return: An XArray internal entry corresponding to this value.
     142             :  */
     143      489059 : static inline void *xa_mk_internal(unsigned long v)
     144             : {
     145       20412 :         return (void *)((v << 2) | 2);
     146             : }
     147             : 
     148             : /*
     149             :  * xa_to_internal() - Extract the value from an internal entry.
     150             :  * @entry: XArray entry.
     151             :  *
     152             :  * Context: Any context.
     153             :  * Return: The value which was stored in the internal entry.
     154             :  */
     155           0 : static inline unsigned long xa_to_internal(const void *entry)
     156             : {
     157           0 :         return (unsigned long)entry >> 2;
     158             : }
     159             : 
     160             : /*
     161             :  * xa_is_internal() - Is the entry an internal entry?
     162             :  * @entry: XArray entry.
     163             :  *
     164             :  * Context: Any context.
     165             :  * Return: %true if the entry is an internal entry.
     166             :  */
     167     2378067 : static inline bool xa_is_internal(const void *entry)
     168             : {
     169        4004 :         return ((unsigned long)entry & 3) == 2;
     170             : }
     171             : 
     172             : #define XA_ZERO_ENTRY           xa_mk_internal(257)
     173             : 
     174             : /**
     175             :  * xa_is_zero() - Is the entry a zero entry?
     176             :  * @entry: Entry retrieved from the XArray
     177             :  *
     178             :  * The normal API will return NULL as the contents of a slot containing
     179             :  * a zero entry.  You can only see zero entries by using the advanced API.
     180             :  *
     181             :  * Return: %true if the entry is a zero entry.
     182             :  */
     183      127593 : static inline bool xa_is_zero(const void *entry)
     184             : {
     185       79161 :         return unlikely(entry == XA_ZERO_ENTRY);
     186             : }
     187             : 
     188             : /**
     189             :  * xa_is_err() - Report whether an XArray operation returned an error
     190             :  * @entry: Result from calling an XArray function
     191             :  *
     192             :  * If an XArray operation cannot complete an operation, it will return
     193             :  * a special value indicating an error.  This function tells you
     194             :  * whether an error occurred; xa_err() tells you which error occurred.
     195             :  *
     196             :  * Context: Any context.
     197             :  * Return: %true if the entry indicates an error.
     198             :  */
     199      671640 : static inline bool xa_is_err(const void *entry)
     200             : {
     201           0 :         return unlikely(xa_is_internal(entry) &&
     202             :                         entry >= xa_mk_internal(-MAX_ERRNO));
     203             : }
     204             : 
     205             : /**
     206             :  * xa_err() - Turn an XArray result into an errno.
     207             :  * @entry: Result from calling an XArray function.
     208             :  *
     209             :  * If an XArray operation cannot complete an operation, it will return
     210             :  * a special pointer value which encodes an errno.  This function extracts
     211             :  * the errno from the pointer value, or returns 0 if the pointer does not
     212             :  * represent an errno.
     213             :  *
     214             :  * Context: Any context.
     215             :  * Return: A negative errno or 0.
     216             :  */
     217      671640 : static inline int xa_err(void *entry)
     218             : {
     219             :         /* xa_to_internal() would not do sign extension. */
     220      671640 :         if (xa_is_err(entry))
     221           0 :                 return (long)entry >> 2;
     222             :         return 0;
     223             : }
     224             : 
     225             : /**
     226             :  * struct xa_limit - Represents a range of IDs.
     227             :  * @min: The lowest ID to allocate (inclusive).
     228             :  * @max: The maximum ID to allocate (inclusive).
     229             :  *
     230             :  * This structure is used either directly or via the XA_LIMIT() macro
     231             :  * to communicate the range of IDs that are valid for allocation.
     232             :  * Two common ranges are predefined for you:
     233             :  * * xa_limit_32b       - [0 - UINT_MAX]
     234             :  * * xa_limit_31b       - [0 - INT_MAX]
     235             :  */
     236             : struct xa_limit {
     237             :         u32 max;
     238             :         u32 min;
     239             : };
     240             : 
     241             : #define XA_LIMIT(_min, _max) (struct xa_limit) { .min = _min, .max = _max }
     242             : 
     243             : #define xa_limit_32b    XA_LIMIT(0, UINT_MAX)
     244             : #define xa_limit_31b    XA_LIMIT(0, INT_MAX)
     245             : 
     246             : typedef unsigned __bitwise xa_mark_t;
     247             : #define XA_MARK_0               ((__force xa_mark_t)0U)
     248             : #define XA_MARK_1               ((__force xa_mark_t)1U)
     249             : #define XA_MARK_2               ((__force xa_mark_t)2U)
     250             : #define XA_PRESENT              ((__force xa_mark_t)8U)
     251             : #define XA_MARK_MAX             XA_MARK_2
     252             : #define XA_FREE_MARK            XA_MARK_0
     253             : 
     254             : enum xa_lock_type {
     255             :         XA_LOCK_IRQ = 1,
     256             :         XA_LOCK_BH = 2,
     257             : };
     258             : 
     259             : /*
     260             :  * Values for xa_flags.  The radix tree stores its GFP flags in the xa_flags,
     261             :  * and we remain compatible with that.
     262             :  */
     263             : #define XA_FLAGS_LOCK_IRQ       ((__force gfp_t)XA_LOCK_IRQ)
     264             : #define XA_FLAGS_LOCK_BH        ((__force gfp_t)XA_LOCK_BH)
     265             : #define XA_FLAGS_TRACK_FREE     ((__force gfp_t)4U)
     266             : #define XA_FLAGS_ZERO_BUSY      ((__force gfp_t)8U)
     267             : #define XA_FLAGS_ALLOC_WRAPPED  ((__force gfp_t)16U)
     268             : #define XA_FLAGS_ACCOUNT        ((__force gfp_t)32U)
     269             : #define XA_FLAGS_MARK(mark)     ((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \
     270             :                                                 (__force unsigned)(mark)))
     271             : 
     272             : /* ALLOC is for a normal 0-based alloc.  ALLOC1 is for an 1-based alloc */
     273             : #define XA_FLAGS_ALLOC  (XA_FLAGS_TRACK_FREE | XA_FLAGS_MARK(XA_FREE_MARK))
     274             : #define XA_FLAGS_ALLOC1 (XA_FLAGS_TRACK_FREE | XA_FLAGS_ZERO_BUSY)
     275             : 
     276             : /**
     277             :  * struct xarray - The anchor of the XArray.
     278             :  * @xa_lock: Lock that protects the contents of the XArray.
     279             :  *
     280             :  * To use the xarray, define it statically or embed it in your data structure.
     281             :  * It is a very small data structure, so it does not usually make sense to
     282             :  * allocate it separately and keep a pointer to it in your data structure.
     283             :  *
     284             :  * You may use the xa_lock to protect your own data structures as well.
     285             :  */
     286             : /*
     287             :  * If all of the entries in the array are NULL, @xa_head is a NULL pointer.
     288             :  * If the only non-NULL entry in the array is at index 0, @xa_head is that
     289             :  * entry.  If any other entry in the array is non-NULL, @xa_head points
     290             :  * to an @xa_node.
     291             :  */
     292             : struct xarray {
     293             :         spinlock_t      xa_lock;
     294             : /* private: The rest of the data structure is not to be used directly. */
     295             :         gfp_t           xa_flags;
     296             :         void __rcu *    xa_head;
     297             : };
     298             : 
     299             : #define XARRAY_INIT(name, flags) {                              \
     300             :         .xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock),          \
     301             :         .xa_flags = flags,                                      \
     302             :         .xa_head = NULL,                                        \
     303             : }
     304             : 
     305             : /**
     306             :  * DEFINE_XARRAY_FLAGS() - Define an XArray with custom flags.
     307             :  * @name: A string that names your XArray.
     308             :  * @flags: XA_FLAG values.
     309             :  *
     310             :  * This is intended for file scope definitions of XArrays.  It declares
     311             :  * and initialises an empty XArray with the chosen name and flags.  It is
     312             :  * equivalent to calling xa_init_flags() on the array, but it does the
     313             :  * initialisation at compiletime instead of runtime.
     314             :  */
     315             : #define DEFINE_XARRAY_FLAGS(name, flags)                                \
     316             :         struct xarray name = XARRAY_INIT(name, flags)
     317             : 
     318             : /**
     319             :  * DEFINE_XARRAY() - Define an XArray.
     320             :  * @name: A string that names your XArray.
     321             :  *
     322             :  * This is intended for file scope definitions of XArrays.  It declares
     323             :  * and initialises an empty XArray with the chosen name.  It is equivalent
     324             :  * to calling xa_init() on the array, but it does the initialisation at
     325             :  * compiletime instead of runtime.
     326             :  */
     327             : #define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0)
     328             : 
     329             : /**
     330             :  * DEFINE_XARRAY_ALLOC() - Define an XArray which allocates IDs starting at 0.
     331             :  * @name: A string that names your XArray.
     332             :  *
     333             :  * This is intended for file scope definitions of allocating XArrays.
     334             :  * See also DEFINE_XARRAY().
     335             :  */
     336             : #define DEFINE_XARRAY_ALLOC(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC)
     337             : 
     338             : /**
     339             :  * DEFINE_XARRAY_ALLOC1() - Define an XArray which allocates IDs starting at 1.
     340             :  * @name: A string that names your XArray.
     341             :  *
     342             :  * This is intended for file scope definitions of allocating XArrays.
     343             :  * See also DEFINE_XARRAY().
     344             :  */
     345             : #define DEFINE_XARRAY_ALLOC1(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC1)
     346             : 
     347             : void *xa_load(struct xarray *, unsigned long index);
     348             : void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
     349             : void *xa_erase(struct xarray *, unsigned long index);
     350             : void *xa_store_range(struct xarray *, unsigned long first, unsigned long last,
     351             :                         void *entry, gfp_t);
     352             : bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t);
     353             : void xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
     354             : void xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
     355             : void *xa_find(struct xarray *xa, unsigned long *index,
     356             :                 unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
     357             : void *xa_find_after(struct xarray *xa, unsigned long *index,
     358             :                 unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
     359             : unsigned int xa_extract(struct xarray *, void **dst, unsigned long start,
     360             :                 unsigned long max, unsigned int n, xa_mark_t);
     361             : void xa_destroy(struct xarray *);
     362             : 
     363             : /**
     364             :  * xa_init_flags() - Initialise an empty XArray with flags.
     365             :  * @xa: XArray.
     366             :  * @flags: XA_FLAG values.
     367             :  *
     368             :  * If you need to initialise an XArray with special flags (eg you need
     369             :  * to take the lock from interrupt context), use this function instead
     370             :  * of xa_init().
     371             :  *
     372             :  * Context: Any context.
     373             :  */
     374       15020 : static inline void xa_init_flags(struct xarray *xa, gfp_t flags)
     375             : {
     376       15029 :         spin_lock_init(&xa->xa_lock);
     377       15020 :         xa->xa_flags = flags;
     378       15020 :         xa->xa_head = NULL;
     379             : }
     380             : 
     381             : /**
     382             :  * xa_init() - Initialise an empty XArray.
     383             :  * @xa: XArray.
     384             :  *
     385             :  * An empty XArray is full of NULL entries.
     386             :  *
     387             :  * Context: Any context.
     388             :  */
     389           9 : static inline void xa_init(struct xarray *xa)
     390             : {
     391           9 :         xa_init_flags(xa, 0);
     392           9 : }
     393             : 
     394             : /**
     395             :  * xa_empty() - Determine if an array has any present entries.
     396             :  * @xa: XArray.
     397             :  *
     398             :  * Context: Any context.
     399             :  * Return: %true if the array contains only NULL pointers.
     400             :  */
     401             : static inline bool xa_empty(const struct xarray *xa)
     402             : {
     403             :         return xa->xa_head == NULL;
     404             : }
     405             : 
     406             : /**
     407             :  * xa_marked() - Inquire whether any entry in this array has a mark set
     408             :  * @xa: Array
     409             :  * @mark: Mark value
     410             :  *
     411             :  * Context: Any context.
     412             :  * Return: %true if any entry has this mark set.
     413             :  */
     414       18680 : static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark)
     415             : {
     416       18680 :         return xa->xa_flags & XA_FLAGS_MARK(mark);
     417             : }
     418             : 
     419             : /**
     420             :  * xa_for_each_range() - Iterate over a portion of an XArray.
     421             :  * @xa: XArray.
     422             :  * @index: Index of @entry.
     423             :  * @entry: Entry retrieved from array.
     424             :  * @start: First index to retrieve from array.
     425             :  * @last: Last index to retrieve from array.
     426             :  *
     427             :  * During the iteration, @entry will have the value of the entry stored
     428             :  * in @xa at @index.  You may modify @index during the iteration if you
     429             :  * want to skip or reprocess indices.  It is safe to modify the array
     430             :  * during the iteration.  At the end of the iteration, @entry will be set
     431             :  * to NULL and @index will have a value less than or equal to max.
     432             :  *
     433             :  * xa_for_each_range() is O(n.log(n)) while xas_for_each() is O(n).  You have
     434             :  * to handle your own locking with xas_for_each(), and if you have to unlock
     435             :  * after each iteration, it will also end up being O(n.log(n)).
     436             :  * xa_for_each_range() will spin if it hits a retry entry; if you intend to
     437             :  * see retry entries, you should use the xas_for_each() iterator instead.
     438             :  * The xas_for_each() iterator will expand into more inline code than
     439             :  * xa_for_each_range().
     440             :  *
     441             :  * Context: Any context.  Takes and releases the RCU lock.
     442             :  */
     443             : #define xa_for_each_range(xa, index, entry, start, last)                \
     444             :         for (index = start,                                             \
     445             :              entry = xa_find(xa, &index, last, XA_PRESENT);         \
     446             :              entry;                                                     \
     447             :              entry = xa_find_after(xa, &index, last, XA_PRESENT))
     448             : 
     449             : /**
     450             :  * xa_for_each_start() - Iterate over a portion of an XArray.
     451             :  * @xa: XArray.
     452             :  * @index: Index of @entry.
     453             :  * @entry: Entry retrieved from array.
     454             :  * @start: First index to retrieve from array.
     455             :  *
     456             :  * During the iteration, @entry will have the value of the entry stored
     457             :  * in @xa at @index.  You may modify @index during the iteration if you
     458             :  * want to skip or reprocess indices.  It is safe to modify the array
     459             :  * during the iteration.  At the end of the iteration, @entry will be set
     460             :  * to NULL and @index will have a value less than or equal to max.
     461             :  *
     462             :  * xa_for_each_start() is O(n.log(n)) while xas_for_each() is O(n).  You have
     463             :  * to handle your own locking with xas_for_each(), and if you have to unlock
     464             :  * after each iteration, it will also end up being O(n.log(n)).
     465             :  * xa_for_each_start() will spin if it hits a retry entry; if you intend to
     466             :  * see retry entries, you should use the xas_for_each() iterator instead.
     467             :  * The xas_for_each() iterator will expand into more inline code than
     468             :  * xa_for_each_start().
     469             :  *
     470             :  * Context: Any context.  Takes and releases the RCU lock.
     471             :  */
     472             : #define xa_for_each_start(xa, index, entry, start) \
     473             :         xa_for_each_range(xa, index, entry, start, ULONG_MAX)
     474             : 
     475             : /**
     476             :  * xa_for_each() - Iterate over present entries in an XArray.
     477             :  * @xa: XArray.
     478             :  * @index: Index of @entry.
     479             :  * @entry: Entry retrieved from array.
     480             :  *
     481             :  * During the iteration, @entry will have the value of the entry stored
     482             :  * in @xa at @index.  You may modify @index during the iteration if you want
     483             :  * to skip or reprocess indices.  It is safe to modify the array during the
     484             :  * iteration.  At the end of the iteration, @entry will be set to NULL and
     485             :  * @index will have a value less than or equal to max.
     486             :  *
     487             :  * xa_for_each() is O(n.log(n)) while xas_for_each() is O(n).  You have
     488             :  * to handle your own locking with xas_for_each(), and if you have to unlock
     489             :  * after each iteration, it will also end up being O(n.log(n)).  xa_for_each()
     490             :  * will spin if it hits a retry entry; if you intend to see retry entries,
     491             :  * you should use the xas_for_each() iterator instead.  The xas_for_each()
     492             :  * iterator will expand into more inline code than xa_for_each().
     493             :  *
     494             :  * Context: Any context.  Takes and releases the RCU lock.
     495             :  */
     496             : #define xa_for_each(xa, index, entry) \
     497             :         xa_for_each_start(xa, index, entry, 0)
     498             : 
     499             : /**
     500             :  * xa_for_each_marked() - Iterate over marked entries in an XArray.
     501             :  * @xa: XArray.
     502             :  * @index: Index of @entry.
     503             :  * @entry: Entry retrieved from array.
     504             :  * @filter: Selection criterion.
     505             :  *
     506             :  * During the iteration, @entry will have the value of the entry stored
     507             :  * in @xa at @index.  The iteration will skip all entries in the array
     508             :  * which do not match @filter.  You may modify @index during the iteration
     509             :  * if you want to skip or reprocess indices.  It is safe to modify the array
     510             :  * during the iteration.  At the end of the iteration, @entry will be set to
     511             :  * NULL and @index will have a value less than or equal to max.
     512             :  *
     513             :  * xa_for_each_marked() is O(n.log(n)) while xas_for_each_marked() is O(n).
     514             :  * You have to handle your own locking with xas_for_each(), and if you have
     515             :  * to unlock after each iteration, it will also end up being O(n.log(n)).
     516             :  * xa_for_each_marked() will spin if it hits a retry entry; if you intend to
     517             :  * see retry entries, you should use the xas_for_each_marked() iterator
     518             :  * instead.  The xas_for_each_marked() iterator will expand into more inline
     519             :  * code than xa_for_each_marked().
     520             :  *
     521             :  * Context: Any context.  Takes and releases the RCU lock.
     522             :  */
     523             : #define xa_for_each_marked(xa, index, entry, filter) \
     524             :         for (index = 0, entry = xa_find(xa, &index, ULONG_MAX, filter); \
     525             :              entry; entry = xa_find_after(xa, &index, ULONG_MAX, filter))
     526             : 
     527             : #define xa_trylock(xa)          spin_trylock(&(xa)->xa_lock)
     528             : #define xa_lock(xa)             spin_lock(&(xa)->xa_lock)
     529             : #define xa_unlock(xa)           spin_unlock(&(xa)->xa_lock)
     530             : #define xa_lock_bh(xa)          spin_lock_bh(&(xa)->xa_lock)
     531             : #define xa_unlock_bh(xa)        spin_unlock_bh(&(xa)->xa_lock)
     532             : #define xa_lock_irq(xa)         spin_lock_irq(&(xa)->xa_lock)
     533             : #define xa_unlock_irq(xa)       spin_unlock_irq(&(xa)->xa_lock)
     534             : #define xa_lock_irqsave(xa, flags) \
     535             :                                 spin_lock_irqsave(&(xa)->xa_lock, flags)
     536             : #define xa_unlock_irqrestore(xa, flags) \
     537             :                                 spin_unlock_irqrestore(&(xa)->xa_lock, flags)
     538             : #define xa_lock_nested(xa, subclass) \
     539             :                                 spin_lock_nested(&(xa)->xa_lock, subclass)
     540             : #define xa_lock_bh_nested(xa, subclass) \
     541             :                                 spin_lock_bh_nested(&(xa)->xa_lock, subclass)
     542             : #define xa_lock_irq_nested(xa, subclass) \
     543             :                                 spin_lock_irq_nested(&(xa)->xa_lock, subclass)
     544             : #define xa_lock_irqsave_nested(xa, flags, subclass) \
     545             :                 spin_lock_irqsave_nested(&(xa)->xa_lock, flags, subclass)
     546             : 
     547             : /*
     548             :  * Versions of the normal API which require the caller to hold the
     549             :  * xa_lock.  If the GFP flags allow it, they will drop the lock to
     550             :  * allocate memory, then reacquire it afterwards.  These functions
     551             :  * may also re-enable interrupts if the XArray flags indicate the
     552             :  * locking should be interrupt safe.
     553             :  */
     554             : void *__xa_erase(struct xarray *, unsigned long index);
     555             : void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
     556             : void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old,
     557             :                 void *entry, gfp_t);
     558             : int __must_check __xa_insert(struct xarray *, unsigned long index,
     559             :                 void *entry, gfp_t);
     560             : int __must_check __xa_alloc(struct xarray *, u32 *id, void *entry,
     561             :                 struct xa_limit, gfp_t);
     562             : int __must_check __xa_alloc_cyclic(struct xarray *, u32 *id, void *entry,
     563             :                 struct xa_limit, u32 *next, gfp_t);
     564             : void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
     565             : void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
     566             : 
     567             : /**
     568             :  * xa_store_bh() - Store this entry in the XArray.
     569             :  * @xa: XArray.
     570             :  * @index: Index into array.
     571             :  * @entry: New entry.
     572             :  * @gfp: Memory allocation flags.
     573             :  *
     574             :  * This function is like calling xa_store() except it disables softirqs
     575             :  * while holding the array lock.
     576             :  *
     577             :  * Context: Any context.  Takes and releases the xa_lock while
     578             :  * disabling softirqs.
     579             :  * Return: The old entry at this index or xa_err() if an error happened.
     580             :  */
     581             : static inline void *xa_store_bh(struct xarray *xa, unsigned long index,
     582             :                 void *entry, gfp_t gfp)
     583             : {
     584             :         void *curr;
     585             : 
     586             :         xa_lock_bh(xa);
     587             :         curr = __xa_store(xa, index, entry, gfp);
     588             :         xa_unlock_bh(xa);
     589             : 
     590             :         return curr;
     591             : }
     592             : 
     593             : /**
     594             :  * xa_store_irq() - Store this entry in the XArray.
     595             :  * @xa: XArray.
     596             :  * @index: Index into array.
     597             :  * @entry: New entry.
     598             :  * @gfp: Memory allocation flags.
     599             :  *
     600             :  * This function is like calling xa_store() except it disables interrupts
     601             :  * while holding the array lock.
     602             :  *
     603             :  * Context: Process context.  Takes and releases the xa_lock while
     604             :  * disabling interrupts.
     605             :  * Return: The old entry at this index or xa_err() if an error happened.
     606             :  */
     607             : static inline void *xa_store_irq(struct xarray *xa, unsigned long index,
     608             :                 void *entry, gfp_t gfp)
     609             : {
     610             :         void *curr;
     611             : 
     612             :         xa_lock_irq(xa);
     613             :         curr = __xa_store(xa, index, entry, gfp);
     614             :         xa_unlock_irq(xa);
     615             : 
     616             :         return curr;
     617             : }
     618             : 
     619             : /**
     620             :  * xa_erase_bh() - Erase this entry from the XArray.
     621             :  * @xa: XArray.
     622             :  * @index: Index of entry.
     623             :  *
     624             :  * After this function returns, loading from @index will return %NULL.
     625             :  * If the index is part of a multi-index entry, all indices will be erased
     626             :  * and none of the entries will be part of a multi-index entry.
     627             :  *
     628             :  * Context: Any context.  Takes and releases the xa_lock while
     629             :  * disabling softirqs.
     630             :  * Return: The entry which used to be at this index.
     631             :  */
     632             : static inline void *xa_erase_bh(struct xarray *xa, unsigned long index)
     633             : {
     634             :         void *entry;
     635             : 
     636             :         xa_lock_bh(xa);
     637             :         entry = __xa_erase(xa, index);
     638             :         xa_unlock_bh(xa);
     639             : 
     640             :         return entry;
     641             : }
     642             : 
     643             : /**
     644             :  * xa_erase_irq() - Erase this entry from the XArray.
     645             :  * @xa: XArray.
     646             :  * @index: Index of entry.
     647             :  *
     648             :  * After this function returns, loading from @index will return %NULL.
     649             :  * If the index is part of a multi-index entry, all indices will be erased
     650             :  * and none of the entries will be part of a multi-index entry.
     651             :  *
     652             :  * Context: Process context.  Takes and releases the xa_lock while
     653             :  * disabling interrupts.
     654             :  * Return: The entry which used to be at this index.
     655             :  */
     656             : static inline void *xa_erase_irq(struct xarray *xa, unsigned long index)
     657             : {
     658             :         void *entry;
     659             : 
     660             :         xa_lock_irq(xa);
     661             :         entry = __xa_erase(xa, index);
     662             :         xa_unlock_irq(xa);
     663             : 
     664             :         return entry;
     665             : }
     666             : 
     667             : /**
     668             :  * xa_cmpxchg() - Conditionally replace an entry in the XArray.
     669             :  * @xa: XArray.
     670             :  * @index: Index into array.
     671             :  * @old: Old value to test against.
     672             :  * @entry: New value to place in array.
     673             :  * @gfp: Memory allocation flags.
     674             :  *
     675             :  * If the entry at @index is the same as @old, replace it with @entry.
     676             :  * If the return value is equal to @old, then the exchange was successful.
     677             :  *
     678             :  * Context: Any context.  Takes and releases the xa_lock.  May sleep
     679             :  * if the @gfp flags permit.
     680             :  * Return: The old value at this index or xa_err() if an error happened.
     681             :  */
     682             : static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index,
     683             :                         void *old, void *entry, gfp_t gfp)
     684             : {
     685             :         void *curr;
     686             : 
     687             :         xa_lock(xa);
     688             :         curr = __xa_cmpxchg(xa, index, old, entry, gfp);
     689             :         xa_unlock(xa);
     690             : 
     691             :         return curr;
     692             : }
     693             : 
     694             : /**
     695             :  * xa_cmpxchg_bh() - Conditionally replace an entry in the XArray.
     696             :  * @xa: XArray.
     697             :  * @index: Index into array.
     698             :  * @old: Old value to test against.
     699             :  * @entry: New value to place in array.
     700             :  * @gfp: Memory allocation flags.
     701             :  *
     702             :  * This function is like calling xa_cmpxchg() except it disables softirqs
     703             :  * while holding the array lock.
     704             :  *
     705             :  * Context: Any context.  Takes and releases the xa_lock while
     706             :  * disabling softirqs.  May sleep if the @gfp flags permit.
     707             :  * Return: The old value at this index or xa_err() if an error happened.
     708             :  */
     709             : static inline void *xa_cmpxchg_bh(struct xarray *xa, unsigned long index,
     710             :                         void *old, void *entry, gfp_t gfp)
     711             : {
     712             :         void *curr;
     713             : 
     714             :         xa_lock_bh(xa);
     715             :         curr = __xa_cmpxchg(xa, index, old, entry, gfp);
     716             :         xa_unlock_bh(xa);
     717             : 
     718             :         return curr;
     719             : }
     720             : 
     721             : /**
     722             :  * xa_cmpxchg_irq() - Conditionally replace an entry in the XArray.
     723             :  * @xa: XArray.
     724             :  * @index: Index into array.
     725             :  * @old: Old value to test against.
     726             :  * @entry: New value to place in array.
     727             :  * @gfp: Memory allocation flags.
     728             :  *
     729             :  * This function is like calling xa_cmpxchg() except it disables interrupts
     730             :  * while holding the array lock.
     731             :  *
     732             :  * Context: Process context.  Takes and releases the xa_lock while
     733             :  * disabling interrupts.  May sleep if the @gfp flags permit.
     734             :  * Return: The old value at this index or xa_err() if an error happened.
     735             :  */
     736           0 : static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index,
     737             :                         void *old, void *entry, gfp_t gfp)
     738             : {
     739           0 :         void *curr;
     740             : 
     741           0 :         xa_lock_irq(xa);
     742           0 :         curr = __xa_cmpxchg(xa, index, old, entry, gfp);
     743           0 :         xa_unlock_irq(xa);
     744             : 
     745           0 :         return curr;
     746             : }
     747             : 
     748             : /**
     749             :  * xa_insert() - Store this entry in the XArray unless another entry is
     750             :  *                      already present.
     751             :  * @xa: XArray.
     752             :  * @index: Index into array.
     753             :  * @entry: New entry.
     754             :  * @gfp: Memory allocation flags.
     755             :  *
     756             :  * Inserting a NULL entry will store a reserved entry (like xa_reserve())
     757             :  * if no entry is present.  Inserting will fail if a reserved entry is
     758             :  * present, even though loading from this index will return NULL.
     759             :  *
     760             :  * Context: Any context.  Takes and releases the xa_lock.  May sleep if
     761             :  * the @gfp flags permit.
     762             :  * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
     763             :  * -ENOMEM if memory could not be allocated.
     764             :  */
     765          10 : static inline int __must_check xa_insert(struct xarray *xa,
     766             :                 unsigned long index, void *entry, gfp_t gfp)
     767             : {
     768          10 :         int err;
     769             : 
     770          10 :         xa_lock(xa);
     771          10 :         err = __xa_insert(xa, index, entry, gfp);
     772          10 :         xa_unlock(xa);
     773             : 
     774          10 :         return err;
     775             : }
     776             : 
     777             : /**
     778             :  * xa_insert_bh() - Store this entry in the XArray unless another entry is
     779             :  *                      already present.
     780             :  * @xa: XArray.
     781             :  * @index: Index into array.
     782             :  * @entry: New entry.
     783             :  * @gfp: Memory allocation flags.
     784             :  *
     785             :  * Inserting a NULL entry will store a reserved entry (like xa_reserve())
     786             :  * if no entry is present.  Inserting will fail if a reserved entry is
     787             :  * present, even though loading from this index will return NULL.
     788             :  *
     789             :  * Context: Any context.  Takes and releases the xa_lock while
     790             :  * disabling softirqs.  May sleep if the @gfp flags permit.
     791             :  * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
     792             :  * -ENOMEM if memory could not be allocated.
     793             :  */
     794             : static inline int __must_check xa_insert_bh(struct xarray *xa,
     795             :                 unsigned long index, void *entry, gfp_t gfp)
     796             : {
     797             :         int err;
     798             : 
     799             :         xa_lock_bh(xa);
     800             :         err = __xa_insert(xa, index, entry, gfp);
     801             :         xa_unlock_bh(xa);
     802             : 
     803             :         return err;
     804             : }
     805             : 
     806             : /**
     807             :  * xa_insert_irq() - Store this entry in the XArray unless another entry is
     808             :  *                      already present.
     809             :  * @xa: XArray.
     810             :  * @index: Index into array.
     811             :  * @entry: New entry.
     812             :  * @gfp: Memory allocation flags.
     813             :  *
     814             :  * Inserting a NULL entry will store a reserved entry (like xa_reserve())
     815             :  * if no entry is present.  Inserting will fail if a reserved entry is
     816             :  * present, even though loading from this index will return NULL.
     817             :  *
     818             :  * Context: Process context.  Takes and releases the xa_lock while
     819             :  * disabling interrupts.  May sleep if the @gfp flags permit.
     820             :  * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
     821             :  * -ENOMEM if memory could not be allocated.
     822             :  */
     823             : static inline int __must_check xa_insert_irq(struct xarray *xa,
     824             :                 unsigned long index, void *entry, gfp_t gfp)
     825             : {
     826             :         int err;
     827             : 
     828             :         xa_lock_irq(xa);
     829             :         err = __xa_insert(xa, index, entry, gfp);
     830             :         xa_unlock_irq(xa);
     831             : 
     832             :         return err;
     833             : }
     834             : 
     835             : /**
     836             :  * xa_alloc() - Find somewhere to store this entry in the XArray.
     837             :  * @xa: XArray.
     838             :  * @id: Pointer to ID.
     839             :  * @entry: New entry.
     840             :  * @limit: Range of ID to allocate.
     841             :  * @gfp: Memory allocation flags.
     842             :  *
     843             :  * Finds an empty entry in @xa between @limit.min and @limit.max,
     844             :  * stores the index into the @id pointer, then stores the entry at
     845             :  * that index.  A concurrent lookup will not see an uninitialised @id.
     846             :  *
     847             :  * Context: Any context.  Takes and releases the xa_lock.  May sleep if
     848             :  * the @gfp flags permit.
     849             :  * Return: 0 on success, -ENOMEM if memory could not be allocated or
     850             :  * -EBUSY if there are no free entries in @limit.
     851             :  */
     852             : static inline __must_check int xa_alloc(struct xarray *xa, u32 *id,
     853             :                 void *entry, struct xa_limit limit, gfp_t gfp)
     854             : {
     855             :         int err;
     856             : 
     857             :         xa_lock(xa);
     858             :         err = __xa_alloc(xa, id, entry, limit, gfp);
     859             :         xa_unlock(xa);
     860             : 
     861             :         return err;
     862             : }
     863             : 
     864             : /**
     865             :  * xa_alloc_bh() - Find somewhere to store this entry in the XArray.
     866             :  * @xa: XArray.
     867             :  * @id: Pointer to ID.
     868             :  * @entry: New entry.
     869             :  * @limit: Range of ID to allocate.
     870             :  * @gfp: Memory allocation flags.
     871             :  *
     872             :  * Finds an empty entry in @xa between @limit.min and @limit.max,
     873             :  * stores the index into the @id pointer, then stores the entry at
     874             :  * that index.  A concurrent lookup will not see an uninitialised @id.
     875             :  *
     876             :  * Context: Any context.  Takes and releases the xa_lock while
     877             :  * disabling softirqs.  May sleep if the @gfp flags permit.
     878             :  * Return: 0 on success, -ENOMEM if memory could not be allocated or
     879             :  * -EBUSY if there are no free entries in @limit.
     880             :  */
     881             : static inline int __must_check xa_alloc_bh(struct xarray *xa, u32 *id,
     882             :                 void *entry, struct xa_limit limit, gfp_t gfp)
     883             : {
     884             :         int err;
     885             : 
     886             :         xa_lock_bh(xa);
     887             :         err = __xa_alloc(xa, id, entry, limit, gfp);
     888             :         xa_unlock_bh(xa);
     889             : 
     890             :         return err;
     891             : }
     892             : 
     893             : /**
     894             :  * xa_alloc_irq() - Find somewhere to store this entry in the XArray.
     895             :  * @xa: XArray.
     896             :  * @id: Pointer to ID.
     897             :  * @entry: New entry.
     898             :  * @limit: Range of ID to allocate.
     899             :  * @gfp: Memory allocation flags.
     900             :  *
     901             :  * Finds an empty entry in @xa between @limit.min and @limit.max,
     902             :  * stores the index into the @id pointer, then stores the entry at
     903             :  * that index.  A concurrent lookup will not see an uninitialised @id.
     904             :  *
     905             :  * Context: Process context.  Takes and releases the xa_lock while
     906             :  * disabling interrupts.  May sleep if the @gfp flags permit.
     907             :  * Return: 0 on success, -ENOMEM if memory could not be allocated or
     908             :  * -EBUSY if there are no free entries in @limit.
     909             :  */
     910             : static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id,
     911             :                 void *entry, struct xa_limit limit, gfp_t gfp)
     912             : {
     913             :         int err;
     914             : 
     915             :         xa_lock_irq(xa);
     916             :         err = __xa_alloc(xa, id, entry, limit, gfp);
     917             :         xa_unlock_irq(xa);
     918             : 
     919             :         return err;
     920             : }
     921             : 
     922             : /**
     923             :  * xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
     924             :  * @xa: XArray.
     925             :  * @id: Pointer to ID.
     926             :  * @entry: New entry.
     927             :  * @limit: Range of allocated ID.
     928             :  * @next: Pointer to next ID to allocate.
     929             :  * @gfp: Memory allocation flags.
     930             :  *
     931             :  * Finds an empty entry in @xa between @limit.min and @limit.max,
     932             :  * stores the index into the @id pointer, then stores the entry at
     933             :  * that index.  A concurrent lookup will not see an uninitialised @id.
     934             :  * The search for an empty entry will start at @next and will wrap
     935             :  * around if necessary.
     936             :  *
     937             :  * Context: Any context.  Takes and releases the xa_lock.  May sleep if
     938             :  * the @gfp flags permit.
     939             :  * Return: 0 if the allocation succeeded without wrapping.  1 if the
     940             :  * allocation succeeded after wrapping, -ENOMEM if memory could not be
     941             :  * allocated or -EBUSY if there are no free entries in @limit.
     942             :  */
     943             : static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
     944             :                 struct xa_limit limit, u32 *next, gfp_t gfp)
     945             : {
     946             :         int err;
     947             : 
     948             :         xa_lock(xa);
     949             :         err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
     950             :         xa_unlock(xa);
     951             : 
     952             :         return err;
     953             : }
     954             : 
     955             : /**
     956             :  * xa_alloc_cyclic_bh() - Find somewhere to store this entry in the XArray.
     957             :  * @xa: XArray.
     958             :  * @id: Pointer to ID.
     959             :  * @entry: New entry.
     960             :  * @limit: Range of allocated ID.
     961             :  * @next: Pointer to next ID to allocate.
     962             :  * @gfp: Memory allocation flags.
     963             :  *
     964             :  * Finds an empty entry in @xa between @limit.min and @limit.max,
     965             :  * stores the index into the @id pointer, then stores the entry at
     966             :  * that index.  A concurrent lookup will not see an uninitialised @id.
     967             :  * The search for an empty entry will start at @next and will wrap
     968             :  * around if necessary.
     969             :  *
     970             :  * Context: Any context.  Takes and releases the xa_lock while
     971             :  * disabling softirqs.  May sleep if the @gfp flags permit.
     972             :  * Return: 0 if the allocation succeeded without wrapping.  1 if the
     973             :  * allocation succeeded after wrapping, -ENOMEM if memory could not be
     974             :  * allocated or -EBUSY if there are no free entries in @limit.
     975             :  */
     976             : static inline int xa_alloc_cyclic_bh(struct xarray *xa, u32 *id, void *entry,
     977             :                 struct xa_limit limit, u32 *next, gfp_t gfp)
     978             : {
     979             :         int err;
     980             : 
     981             :         xa_lock_bh(xa);
     982             :         err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
     983             :         xa_unlock_bh(xa);
     984             : 
     985             :         return err;
     986             : }
     987             : 
     988             : /**
     989             :  * xa_alloc_cyclic_irq() - Find somewhere to store this entry in the XArray.
     990             :  * @xa: XArray.
     991             :  * @id: Pointer to ID.
     992             :  * @entry: New entry.
     993             :  * @limit: Range of allocated ID.
     994             :  * @next: Pointer to next ID to allocate.
     995             :  * @gfp: Memory allocation flags.
     996             :  *
     997             :  * Finds an empty entry in @xa between @limit.min and @limit.max,
     998             :  * stores the index into the @id pointer, then stores the entry at
     999             :  * that index.  A concurrent lookup will not see an uninitialised @id.
    1000             :  * The search for an empty entry will start at @next and will wrap
    1001             :  * around if necessary.
    1002             :  *
    1003             :  * Context: Process context.  Takes and releases the xa_lock while
    1004             :  * disabling interrupts.  May sleep if the @gfp flags permit.
    1005             :  * Return: 0 if the allocation succeeded without wrapping.  1 if the
    1006             :  * allocation succeeded after wrapping, -ENOMEM if memory could not be
    1007             :  * allocated or -EBUSY if there are no free entries in @limit.
    1008             :  */
    1009             : static inline int xa_alloc_cyclic_irq(struct xarray *xa, u32 *id, void *entry,
    1010             :                 struct xa_limit limit, u32 *next, gfp_t gfp)
    1011             : {
    1012             :         int err;
    1013             : 
    1014             :         xa_lock_irq(xa);
    1015             :         err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
    1016             :         xa_unlock_irq(xa);
    1017             : 
    1018             :         return err;
    1019             : }
    1020             : 
    1021             : /**
    1022             :  * xa_reserve() - Reserve this index in the XArray.
    1023             :  * @xa: XArray.
    1024             :  * @index: Index into array.
    1025             :  * @gfp: Memory allocation flags.
    1026             :  *
    1027             :  * Ensures there is somewhere to store an entry at @index in the array.
    1028             :  * If there is already something stored at @index, this function does
    1029             :  * nothing.  If there was nothing there, the entry is marked as reserved.
    1030             :  * Loading from a reserved entry returns a %NULL pointer.
    1031             :  *
    1032             :  * If you do not use the entry that you have reserved, call xa_release()
    1033             :  * or xa_erase() to free any unnecessary memory.
    1034             :  *
    1035             :  * Context: Any context.  Takes and releases the xa_lock.
    1036             :  * May sleep if the @gfp flags permit.
    1037             :  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
    1038             :  */
    1039             : static inline __must_check
    1040             : int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
    1041             : {
    1042             :         return xa_err(xa_cmpxchg(xa, index, NULL, XA_ZERO_ENTRY, gfp));
    1043             : }
    1044             : 
    1045             : /**
    1046             :  * xa_reserve_bh() - Reserve this index in the XArray.
    1047             :  * @xa: XArray.
    1048             :  * @index: Index into array.
    1049             :  * @gfp: Memory allocation flags.
    1050             :  *
    1051             :  * A softirq-disabling version of xa_reserve().
    1052             :  *
    1053             :  * Context: Any context.  Takes and releases the xa_lock while
    1054             :  * disabling softirqs.
    1055             :  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
    1056             :  */
    1057             : static inline __must_check
    1058             : int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp)
    1059             : {
    1060             :         return xa_err(xa_cmpxchg_bh(xa, index, NULL, XA_ZERO_ENTRY, gfp));
    1061             : }
    1062             : 
    1063             : /**
    1064             :  * xa_reserve_irq() - Reserve this index in the XArray.
    1065             :  * @xa: XArray.
    1066             :  * @index: Index into array.
    1067             :  * @gfp: Memory allocation flags.
    1068             :  *
    1069             :  * An interrupt-disabling version of xa_reserve().
    1070             :  *
    1071             :  * Context: Process context.  Takes and releases the xa_lock while
    1072             :  * disabling interrupts.
    1073             :  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
    1074             :  */
    1075             : static inline __must_check
    1076             : int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp)
    1077             : {
    1078             :         return xa_err(xa_cmpxchg_irq(xa, index, NULL, XA_ZERO_ENTRY, gfp));
    1079             : }
    1080             : 
    1081             : /**
    1082             :  * xa_release() - Release a reserved entry.
    1083             :  * @xa: XArray.
    1084             :  * @index: Index of entry.
    1085             :  *
    1086             :  * After calling xa_reserve(), you can call this function to release the
    1087             :  * reservation.  If the entry at @index has been stored to, this function
    1088             :  * will do nothing.
    1089             :  */
    1090             : static inline void xa_release(struct xarray *xa, unsigned long index)
    1091             : {
    1092             :         xa_cmpxchg(xa, index, XA_ZERO_ENTRY, NULL, 0);
    1093             : }
    1094             : 
    1095             : /* Everything below here is the Advanced API.  Proceed with caution. */
    1096             : 
    1097             : /*
    1098             :  * The xarray is constructed out of a set of 'chunks' of pointers.  Choosing
    1099             :  * the best chunk size requires some tradeoffs.  A power of two recommends
    1100             :  * itself so that we can walk the tree based purely on shifts and masks.
    1101             :  * Generally, the larger the better; as the number of slots per level of the
    1102             :  * tree increases, the less tall the tree needs to be.  But that needs to be
    1103             :  * balanced against the memory consumption of each node.  On a 64-bit system,
    1104             :  * xa_node is currently 576 bytes, and we get 7 of them per 4kB page.  If we
    1105             :  * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
    1106             :  */
    1107             : #ifndef XA_CHUNK_SHIFT
    1108             : #define XA_CHUNK_SHIFT          (CONFIG_BASE_SMALL ? 4 : 6)
    1109             : #endif
    1110             : #define XA_CHUNK_SIZE           (1UL << XA_CHUNK_SHIFT)
    1111             : #define XA_CHUNK_MASK           (XA_CHUNK_SIZE - 1)
    1112             : #define XA_MAX_MARKS            3
    1113             : #define XA_MARK_LONGS           DIV_ROUND_UP(XA_CHUNK_SIZE, BITS_PER_LONG)
    1114             : 
    1115             : /*
    1116             :  * @count is the count of every non-NULL element in the ->slots array
    1117             :  * whether that is a value entry, a retry entry, a user pointer,
    1118             :  * a sibling entry or a pointer to the next level of the tree.
    1119             :  * @nr_values is the count of every element in ->slots which is
    1120             :  * either a value entry or a sibling of a value entry.
    1121             :  */
    1122             : struct xa_node {
    1123             :         unsigned char   shift;          /* Bits remaining in each slot */
    1124             :         unsigned char   offset;         /* Slot offset in parent */
    1125             :         unsigned char   count;          /* Total entry count */
    1126             :         unsigned char   nr_values;      /* Value entry count */
    1127             :         struct xa_node __rcu *parent;   /* NULL at top of tree */
    1128             :         struct xarray   *array;         /* The array we belong to */
    1129             :         union {
    1130             :                 struct list_head private_list;  /* For tree user */
    1131             :                 struct rcu_head rcu_head;       /* Used when freeing node */
    1132             :         };
    1133             :         void __rcu      *slots[XA_CHUNK_SIZE];
    1134             :         union {
    1135             :                 unsigned long   tags[XA_MAX_MARKS][XA_MARK_LONGS];
    1136             :                 unsigned long   marks[XA_MAX_MARKS][XA_MARK_LONGS];
    1137             :         };
    1138             : };
    1139             : 
    1140             : void xa_dump(const struct xarray *);
    1141             : void xa_dump_node(const struct xa_node *);
    1142             : 
    1143             : #ifdef XA_DEBUG
    1144             : #define XA_BUG_ON(xa, x) do {                                   \
    1145             :                 if (x) {                                        \
    1146             :                         xa_dump(xa);                            \
    1147             :                         BUG();                                  \
    1148             :                 }                                               \
    1149             :         } while (0)
    1150             : #define XA_NODE_BUG_ON(node, x) do {                            \
    1151             :                 if (x) {                                        \
    1152             :                         if (node) xa_dump_node(node);           \
    1153             :                         BUG();                                  \
    1154             :                 }                                               \
    1155             :         } while (0)
    1156             : #else
    1157             : #define XA_BUG_ON(xa, x)        do { } while (0)
    1158             : #define XA_NODE_BUG_ON(node, x) do { } while (0)
    1159             : #endif
    1160             : 
    1161             : /* Private */
    1162      321060 : static inline void *xa_head(const struct xarray *xa)
    1163             : {
    1164      321060 :         return rcu_dereference_check(xa->xa_head,
    1165             :                                                 lockdep_is_held(&xa->xa_lock));
    1166             : }
    1167             : 
    1168             : /* Private */
    1169        5816 : static inline void *xa_head_locked(const struct xarray *xa)
    1170             : {
    1171        5816 :         return rcu_dereference_protected(xa->xa_head,
    1172             :                                                 lockdep_is_held(&xa->xa_lock));
    1173             : }
    1174             : 
    1175             : /* Private */
    1176      651557 : static inline void *xa_entry(const struct xarray *xa,
    1177             :                                 const struct xa_node *node, unsigned int offset)
    1178             : {
    1179      651557 :         XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
    1180      651557 :         return rcu_dereference_check(node->slots[offset],
    1181             :                                                 lockdep_is_held(&xa->xa_lock));
    1182             : }
    1183             : 
    1184             : /* Private */
    1185       31759 : static inline void *xa_entry_locked(const struct xarray *xa,
    1186             :                                 const struct xa_node *node, unsigned int offset)
    1187             : {
    1188       31759 :         XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
    1189       31759 :         return rcu_dereference_protected(node->slots[offset],
    1190             :                                                 lockdep_is_held(&xa->xa_lock));
    1191             : }
    1192             : 
    1193             : /* Private */
    1194       20593 : static inline struct xa_node *xa_parent(const struct xarray *xa,
    1195             :                                         const struct xa_node *node)
    1196             : {
    1197       20593 :         return rcu_dereference_check(node->parent,
    1198             :                                                 lockdep_is_held(&xa->xa_lock));
    1199             : }
    1200             : 
    1201             : /* Private */
    1202        6512 : static inline struct xa_node *xa_parent_locked(const struct xarray *xa,
    1203             :                                         const struct xa_node *node)
    1204             : {
    1205        6512 :         return rcu_dereference_protected(node->parent,
    1206             :                                                 lockdep_is_held(&xa->xa_lock));
    1207             : }
    1208             : 
    1209             : /* Private */
    1210        1206 : static inline void *xa_mk_node(const struct xa_node *node)
    1211             : {
    1212        1206 :         return (void *)((unsigned long)node | 2);
    1213             : }
    1214             : 
    1215             : /* Private */
    1216      912982 : static inline struct xa_node *xa_to_node(const void *entry)
    1217             : {
    1218      912914 :         return (struct xa_node *)((unsigned long)entry - 2);
    1219             : }
    1220             : 
    1221             : /* Private */
    1222     1088159 : static inline bool xa_is_node(const void *entry)
    1223             : {
    1224     1263403 :         return xa_is_internal(entry) && (unsigned long)entry > 4096;
    1225             : }
    1226             : 
    1227             : /* Private */
    1228      292622 : static inline void *xa_mk_sibling(unsigned int offset)
    1229             : {
    1230           0 :         return xa_mk_internal(offset);
    1231             : }
    1232             : 
    1233             : /* Private */
    1234           0 : static inline unsigned long xa_to_sibling(const void *entry)
    1235             : {
    1236           0 :         return xa_to_internal(entry);
    1237             : }
    1238             : 
    1239             : /**
    1240             :  * xa_is_sibling() - Is the entry a sibling entry?
    1241             :  * @entry: Entry retrieved from the XArray
    1242             :  *
    1243             :  * Return: %true if the entry is a sibling entry.
    1244             :  */
    1245      618224 : static inline bool xa_is_sibling(const void *entry)
    1246             : {
    1247      909546 :         return IS_ENABLED(CONFIG_XARRAY_MULTI) && xa_is_internal(entry) &&
    1248      292622 :                 (entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
    1249             : }
    1250             : 
    1251             : #define XA_RETRY_ENTRY          xa_mk_internal(256)
    1252             : 
    1253             : /**
    1254             :  * xa_is_retry() - Is the entry a retry entry?
    1255             :  * @entry: Entry retrieved from the XArray
    1256             :  *
    1257             :  * Return: %true if the entry is a retry entry.
    1258             :  */
    1259       48432 : static inline bool xa_is_retry(const void *entry)
    1260             : {
    1261       48432 :         return unlikely(entry == XA_RETRY_ENTRY);
    1262             : }
    1263             : 
    1264             : /**
    1265             :  * xa_is_advanced() - Is the entry only permitted for the advanced API?
    1266             :  * @entry: Entry to be stored in the XArray.
    1267             :  *
    1268             :  * Return: %true if the entry cannot be stored by the normal API.
    1269             :  */
    1270          14 : static inline bool xa_is_advanced(const void *entry)
    1271             : {
    1272          14 :         return xa_is_internal(entry) && (entry <= XA_RETRY_ENTRY);
    1273             : }
    1274             : 
    1275             : /**
    1276             :  * typedef xa_update_node_t - A callback function from the XArray.
    1277             :  * @node: The node which is being processed
    1278             :  *
    1279             :  * This function is called every time the XArray updates the count of
    1280             :  * present and value entries in a node.  It allows advanced users to
    1281             :  * maintain the private_list in the node.
    1282             :  *
    1283             :  * Context: The xa_lock is held and interrupts may be disabled.
    1284             :  *          Implementations should not drop the xa_lock, nor re-enable
    1285             :  *          interrupts.
    1286             :  */
    1287             : typedef void (*xa_update_node_t)(struct xa_node *node);
    1288             : 
    1289             : void xa_delete_node(struct xa_node *, xa_update_node_t);
    1290             : 
    1291             : /*
    1292             :  * The xa_state is opaque to its users.  It contains various different pieces
    1293             :  * of state involved in the current operation on the XArray.  It should be
    1294             :  * declared on the stack and passed between the various internal routines.
    1295             :  * The various elements in it should not be accessed directly, but only
    1296             :  * through the provided accessor functions.  The below documentation is for
    1297             :  * the benefit of those working on the code, not for users of the XArray.
    1298             :  *
    1299             :  * @xa_node usually points to the xa_node containing the slot we're operating
    1300             :  * on (and @xa_offset is the offset in the slots array).  If there is a
    1301             :  * single entry in the array at index 0, there are no allocated xa_nodes to
    1302             :  * point to, and so we store %NULL in @xa_node.  @xa_node is set to
    1303             :  * the value %XAS_RESTART if the xa_state is not walked to the correct
    1304             :  * position in the tree of nodes for this operation.  If an error occurs
    1305             :  * during an operation, it is set to an %XAS_ERROR value.  If we run off the
    1306             :  * end of the allocated nodes, it is set to %XAS_BOUNDS.
    1307             :  */
    1308             : struct xa_state {
    1309             :         struct xarray *xa;
    1310             :         unsigned long xa_index;
    1311             :         unsigned char xa_shift;
    1312             :         unsigned char xa_sibs;
    1313             :         unsigned char xa_offset;
    1314             :         unsigned char xa_pad;           /* Helps gcc generate better code */
    1315             :         struct xa_node *xa_node;
    1316             :         struct xa_node *xa_alloc;
    1317             :         xa_update_node_t xa_update;
    1318             : };
    1319             : 
    1320             : /*
    1321             :  * We encode errnos in the xas->xa_node.  If an error has happened, we need to
    1322             :  * drop the lock to fix it, and once we've done so the xa_state is invalid.
    1323             :  */
    1324             : #define XA_ERROR(errno) ((struct xa_node *)(((unsigned long)errno << 2) | 2UL))
    1325             : #define XAS_BOUNDS      ((struct xa_node *)1UL)
    1326             : #define XAS_RESTART     ((struct xa_node *)3UL)
    1327             : 
    1328             : #define __XA_STATE(array, index, shift, sibs)  {        \
    1329             :         .xa = array,                                    \
    1330             :         .xa_index = index,                              \
    1331             :         .xa_shift = shift,                              \
    1332             :         .xa_sibs = sibs,                                \
    1333             :         .xa_offset = 0,                                 \
    1334             :         .xa_pad = 0,                                    \
    1335             :         .xa_node = XAS_RESTART,                         \
    1336             :         .xa_alloc = NULL,                               \
    1337             :         .xa_update = NULL                               \
    1338             : }
    1339             : 
    1340             : /**
    1341             :  * XA_STATE() - Declare an XArray operation state.
    1342             :  * @name: Name of this operation state (usually xas).
    1343             :  * @array: Array to operate on.
    1344             :  * @index: Initial index of interest.
    1345             :  *
    1346             :  * Declare and initialise an xa_state on the stack.
    1347             :  */
    1348             : #define XA_STATE(name, array, index)                            \
    1349             :         struct xa_state name = __XA_STATE(array, index, 0, 0)
    1350             : 
    1351             : /**
    1352             :  * XA_STATE_ORDER() - Declare an XArray operation state.
    1353             :  * @name: Name of this operation state (usually xas).
    1354             :  * @array: Array to operate on.
    1355             :  * @index: Initial index of interest.
    1356             :  * @order: Order of entry.
    1357             :  *
    1358             :  * Declare and initialise an xa_state on the stack.  This variant of
    1359             :  * XA_STATE() allows you to specify the 'order' of the element you
    1360             :  * want to operate on.`
    1361             :  */
    1362             : #define XA_STATE_ORDER(name, array, index, order)               \
    1363             :         struct xa_state name = __XA_STATE(array,                \
    1364             :                         (index >> order) << order,          \
    1365             :                         order - (order % XA_CHUNK_SHIFT),       \
    1366             :                         (1U << (order % XA_CHUNK_SHIFT)) - 1)
    1367             : 
    1368             : #define xas_marked(xas, mark)   xa_marked((xas)->xa, (mark))
    1369             : #define xas_trylock(xas)        xa_trylock((xas)->xa)
    1370             : #define xas_lock(xas)           xa_lock((xas)->xa)
    1371             : #define xas_unlock(xas)         xa_unlock((xas)->xa)
    1372             : #define xas_lock_bh(xas)        xa_lock_bh((xas)->xa)
    1373             : #define xas_unlock_bh(xas)      xa_unlock_bh((xas)->xa)
    1374             : #define xas_lock_irq(xas)       xa_lock_irq((xas)->xa)
    1375             : #define xas_unlock_irq(xas)     xa_unlock_irq((xas)->xa)
    1376             : #define xas_lock_irqsave(xas, flags) \
    1377             :                                 xa_lock_irqsave((xas)->xa, flags)
    1378             : #define xas_unlock_irqrestore(xas, flags) \
    1379             :                                 xa_unlock_irqrestore((xas)->xa, flags)
    1380             : 
    1381             : /**
    1382             :  * xas_error() - Return an errno stored in the xa_state.
    1383             :  * @xas: XArray operation state.
    1384             :  *
    1385             :  * Return: 0 if no error has been noted.  A negative errno if one has.
    1386             :  */
    1387      671636 : static inline int xas_error(const struct xa_state *xas)
    1388             : {
    1389     1341273 :         return xa_err(xas->xa_node);
    1390             : }
    1391             : 
    1392             : /**
    1393             :  * xas_set_err() - Note an error in the xa_state.
    1394             :  * @xas: XArray operation state.
    1395             :  * @err: Negative error number.
    1396             :  *
    1397             :  * Only call this function with a negative @err; zero or positive errors
    1398             :  * will probably not behave the way you think they should.  If you want
    1399             :  * to clear the error from an xa_state, use xas_reset().
    1400             :  */
    1401           0 : static inline void xas_set_err(struct xa_state *xas, long err)
    1402             : {
    1403           0 :         xas->xa_node = XA_ERROR(err);
    1404           0 : }
    1405             : 
    1406             : /**
    1407             :  * xas_invalid() - Is the xas in a retry or error state?
    1408             :  * @xas: XArray operation state.
    1409             :  *
    1410             :  * Return: %true if the xas cannot be used for operations.
    1411             :  */
    1412      378124 : static inline bool xas_invalid(const struct xa_state *xas)
    1413             : {
    1414       56787 :         return (unsigned long)xas->xa_node & 3;
    1415             : }
    1416             : 
    1417             : /**
    1418             :  * xas_valid() - Is the xas a valid cursor into the array?
    1419             :  * @xas: XArray operation state.
    1420             :  *
    1421             :  * Return: %true if the xas can be used for operations.
    1422             :  */
    1423      321337 : static inline bool xas_valid(const struct xa_state *xas)
    1424             : {
    1425      319351 :         return !xas_invalid(xas);
    1426             : }
    1427             : 
    1428             : /**
    1429             :  * xas_is_node() - Does the xas point to a node?
    1430             :  * @xas: XArray operation state.
    1431             :  *
    1432             :  * Return: %true if the xas currently references a node.
    1433             :  */
    1434        1986 : static inline bool xas_is_node(const struct xa_state *xas)
    1435             : {
    1436        2135 :         return xas_valid(xas) && xas->xa_node;
    1437             : }
    1438             : 
    1439             : /* True if the pointer is something other than a node */
    1440        4920 : static inline bool xas_not_node(struct xa_node *node)
    1441             : {
    1442        5435 :         return ((unsigned long)node & 3) || !node;
    1443             : }
    1444             : 
    1445             : /* True if the node represents RESTART or an error */
    1446        5277 : static inline bool xas_frozen(struct xa_node *node)
    1447             : {
    1448        5277 :         return (unsigned long)node & 2;
    1449             : }
    1450             : 
    1451             : /* True if the node represents head-of-tree, RESTART or BOUNDS */
    1452       69603 : static inline bool xas_top(struct xa_node *node)
    1453             : {
    1454       69603 :         return node <= XAS_RESTART;
    1455             : }
    1456             : 
    1457             : /**
    1458             :  * xas_reset() - Reset an XArray operation state.
    1459             :  * @xas: XArray operation state.
    1460             :  *
    1461             :  * Resets the error or walk state of the @xas so future walks of the
    1462             :  * array will start from the root.  Use this if you have dropped the
    1463             :  * xarray lock and want to reuse the xa_state.
    1464             :  *
    1465             :  * Context: Any context.
    1466             :  */
    1467           0 : static inline void xas_reset(struct xa_state *xas)
    1468             : {
    1469           0 :         xas->xa_node = XAS_RESTART;
    1470           0 : }
    1471             : 
    1472             : /**
    1473             :  * xas_retry() - Retry the operation if appropriate.
    1474             :  * @xas: XArray operation state.
    1475             :  * @entry: Entry from xarray.
    1476             :  *
    1477             :  * The advanced functions may sometimes return an internal entry, such as
    1478             :  * a retry entry or a zero entry.  This function sets up the @xas to restart
    1479             :  * the walk from the head of the array if needed.
    1480             :  *
    1481             :  * Context: Any context.
    1482             :  * Return: true if the operation needs to be retried.
    1483             :  */
    1484       48432 : static inline bool xas_retry(struct xa_state *xas, const void *entry)
    1485             : {
    1486       48432 :         if (xa_is_zero(entry))
    1487             :                 return true;
    1488       48432 :         if (!xa_is_retry(entry))
    1489             :                 return false;
    1490           0 :         xas_reset(xas);
    1491           0 :         return true;
    1492             : }
    1493             : 
    1494             : void *xas_load(struct xa_state *);
    1495             : void *xas_store(struct xa_state *, void *entry);
    1496             : void *xas_find(struct xa_state *, unsigned long max);
    1497             : void *xas_find_conflict(struct xa_state *);
    1498             : 
    1499             : bool xas_get_mark(const struct xa_state *, xa_mark_t);
    1500             : void xas_set_mark(const struct xa_state *, xa_mark_t);
    1501             : void xas_clear_mark(const struct xa_state *, xa_mark_t);
    1502             : void *xas_find_marked(struct xa_state *, unsigned long max, xa_mark_t);
    1503             : void xas_init_marks(const struct xa_state *);
    1504             : 
    1505             : bool xas_nomem(struct xa_state *, gfp_t);
    1506             : void xas_pause(struct xa_state *);
    1507             : 
    1508             : void xas_create_range(struct xa_state *);
    1509             : 
    1510             : #ifdef CONFIG_XARRAY_MULTI
    1511             : int xa_get_order(struct xarray *, unsigned long index);
    1512             : void xas_split(struct xa_state *, void *entry, unsigned int order);
    1513             : void xas_split_alloc(struct xa_state *, void *entry, unsigned int order, gfp_t);
    1514             : #else
    1515             : static inline int xa_get_order(struct xarray *xa, unsigned long index)
    1516             : {
    1517             :         return 0;
    1518             : }
    1519             : 
    1520             : static inline void xas_split(struct xa_state *xas, void *entry,
    1521             :                 unsigned int order)
    1522             : {
    1523             :         xas_store(xas, entry);
    1524             : }
    1525             : 
    1526             : static inline void xas_split_alloc(struct xa_state *xas, void *entry,
    1527             :                 unsigned int order, gfp_t gfp)
    1528             : {
    1529             : }
    1530             : #endif
    1531             : 
    1532             : /**
    1533             :  * xas_reload() - Refetch an entry from the xarray.
    1534             :  * @xas: XArray operation state.
    1535             :  *
    1536             :  * Use this function to check that a previously loaded entry still has
    1537             :  * the same value.  This is useful for the lockless pagecache lookup where
    1538             :  * we walk the array with only the RCU lock to protect us, lock the page,
    1539             :  * then check that the page hasn't moved since we looked it up.
    1540             :  *
    1541             :  * The caller guarantees that @xas is still valid.  If it may be in an
    1542             :  * error or restart state, call xas_load() instead.
    1543             :  *
    1544             :  * Return: The entry at this location in the xarray.
    1545             :  */
    1546        1312 : static inline void *xas_reload(struct xa_state *xas)
    1547             : {
    1548        1312 :         struct xa_node *node = xas->xa_node;
    1549        1312 :         void *entry;
    1550        1312 :         char offset;
    1551             : 
    1552        1312 :         if (!node)
    1553          12 :                 return xa_head(xas->xa);
    1554        1300 :         if (IS_ENABLED(CONFIG_XARRAY_MULTI)) {
    1555        1300 :                 offset = (xas->xa_index >> node->shift) & XA_CHUNK_MASK;
    1556        1300 :                 entry = xa_entry(xas->xa, node, offset);
    1557        1300 :                 if (!xa_is_sibling(entry))
    1558             :                         return entry;
    1559           0 :                 offset = xa_to_sibling(entry);
    1560             :         } else {
    1561             :                 offset = xas->xa_offset;
    1562             :         }
    1563           0 :         return xa_entry(xas->xa, node, offset);
    1564             : }
    1565             : 
    1566             : /**
    1567             :  * xas_set() - Set up XArray operation state for a different index.
    1568             :  * @xas: XArray operation state.
    1569             :  * @index: New index into the XArray.
    1570             :  *
    1571             :  * Move the operation state to refer to a different index.  This will
    1572             :  * have the effect of starting a walk from the top; see xas_next()
    1573             :  * to move to an adjacent index.
    1574             :  */
    1575           0 : static inline void xas_set(struct xa_state *xas, unsigned long index)
    1576             : {
    1577           0 :         xas->xa_index = index;
    1578           0 :         xas->xa_node = XAS_RESTART;
    1579           0 : }
    1580             : 
    1581             : /**
    1582             :  * xas_set_order() - Set up XArray operation state for a multislot entry.
    1583             :  * @xas: XArray operation state.
    1584             :  * @index: Target of the operation.
    1585             :  * @order: Entry occupies 2^@order indices.
    1586             :  */
    1587           0 : static inline void xas_set_order(struct xa_state *xas, unsigned long index,
    1588             :                                         unsigned int order)
    1589             : {
    1590             : #ifdef CONFIG_XARRAY_MULTI
    1591           0 :         xas->xa_index = order < BITS_PER_LONG ? (index >> order) << order : 0;
    1592           0 :         xas->xa_shift = order - (order % XA_CHUNK_SHIFT);
    1593           0 :         xas->xa_sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
    1594           0 :         xas->xa_node = XAS_RESTART;
    1595             : #else
    1596             :         BUG_ON(order > 0);
    1597             :         xas_set(xas, index);
    1598             : #endif
    1599             : }
    1600             : 
    1601             : /**
    1602             :  * xas_set_update() - Set up XArray operation state for a callback.
    1603             :  * @xas: XArray operation state.
    1604             :  * @update: Function to call when updating a node.
    1605             :  *
    1606             :  * The XArray can notify a caller after it has updated an xa_node.
    1607             :  * This is advanced functionality and is only needed by the page cache.
    1608             :  */
    1609           0 : static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
    1610             : {
    1611           0 :         xas->xa_update = update;
    1612           0 : }
    1613             : 
    1614             : /**
    1615             :  * xas_next_entry() - Advance iterator to next present entry.
    1616             :  * @xas: XArray operation state.
    1617             :  * @max: Highest index to return.
    1618             :  *
    1619             :  * xas_next_entry() is an inline function to optimise xarray traversal for
    1620             :  * speed.  It is equivalent to calling xas_find(), and will call xas_find()
    1621             :  * for all the hard cases.
    1622             :  *
    1623             :  * Return: The next present entry after the one currently referred to by @xas.
    1624             :  */
    1625           0 : static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
    1626             : {
    1627           0 :         struct xa_node *node = xas->xa_node;
    1628           0 :         void *entry;
    1629             : 
    1630           0 :         if (unlikely(xas_not_node(node) || node->shift ||
    1631             :                         xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)))
    1632           0 :                 return xas_find(xas, max);
    1633             : 
    1634           0 :         do {
    1635           0 :                 if (unlikely(xas->xa_index >= max))
    1636           0 :                         return xas_find(xas, max);
    1637           0 :                 if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
    1638           0 :                         return xas_find(xas, max);
    1639           0 :                 entry = xa_entry(xas->xa, node, xas->xa_offset + 1);
    1640           0 :                 if (unlikely(xa_is_internal(entry)))
    1641           0 :                         return xas_find(xas, max);
    1642           0 :                 xas->xa_offset++;
    1643           0 :                 xas->xa_index++;
    1644           0 :         } while (!entry);
    1645             : 
    1646             :         return entry;
    1647             : }
    1648             : 
    1649             : /* Private */
    1650        5169 : static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
    1651             :                 xa_mark_t mark)
    1652             : {
    1653        5169 :         unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark];
    1654        5169 :         unsigned int offset = xas->xa_offset;
    1655             : 
    1656        5169 :         if (advance)
    1657        3911 :                 offset++;
    1658        5169 :         if (XA_CHUNK_SIZE == BITS_PER_LONG) {
    1659        5169 :                 if (offset < XA_CHUNK_SIZE) {
    1660        5134 :                         unsigned long data = *addr & (~0UL << offset);
    1661        5134 :                         if (data)
    1662        4492 :                                 return __ffs(data);
    1663             :                 }
    1664             :                 return XA_CHUNK_SIZE;
    1665             :         }
    1666             : 
    1667             :         return find_next_bit(addr, XA_CHUNK_SIZE, offset);
    1668             : }
    1669             : 
    1670             : /**
    1671             :  * xas_next_marked() - Advance iterator to next marked entry.
    1672             :  * @xas: XArray operation state.
    1673             :  * @max: Highest index to return.
    1674             :  * @mark: Mark to search for.
    1675             :  *
    1676             :  * xas_next_marked() is an inline function to optimise xarray traversal for
    1677             :  * speed.  It is equivalent to calling xas_find_marked(), and will call
    1678             :  * xas_find_marked() for all the hard cases.
    1679             :  *
    1680             :  * Return: The next marked entry after the one currently referred to by @xas.
    1681             :  */
    1682         364 : static inline void *xas_next_marked(struct xa_state *xas, unsigned long max,
    1683             :                                                                 xa_mark_t mark)
    1684             : {
    1685         364 :         struct xa_node *node = xas->xa_node;
    1686         364 :         void *entry;
    1687         364 :         unsigned int offset;
    1688             : 
    1689         728 :         if (unlikely(xas_not_node(node) || node->shift))
    1690           9 :                 return xas_find_marked(xas, max, mark);
    1691         355 :         offset = xas_find_chunk(xas, true, mark);
    1692         355 :         xas->xa_offset = offset;
    1693         355 :         xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
    1694         355 :         if (xas->xa_index > max)
    1695             :                 return NULL;
    1696         327 :         if (offset == XA_CHUNK_SIZE)
    1697          33 :                 return xas_find_marked(xas, max, mark);
    1698         294 :         entry = xa_entry(xas->xa, node, offset);
    1699         294 :         if (!entry)
    1700           0 :                 return xas_find_marked(xas, max, mark);
    1701             :         return entry;
    1702             : }
    1703             : 
    1704             : /*
    1705             :  * If iterating while holding a lock, drop the lock and reschedule
    1706             :  * every %XA_CHECK_SCHED loops.
    1707             :  */
    1708             : enum {
    1709             :         XA_CHECK_SCHED = 4096,
    1710             : };
    1711             : 
    1712             : /**
    1713             :  * xas_for_each() - Iterate over a range of an XArray.
    1714             :  * @xas: XArray operation state.
    1715             :  * @entry: Entry retrieved from the array.
    1716             :  * @max: Maximum index to retrieve from array.
    1717             :  *
    1718             :  * The loop body will be executed for each entry present in the xarray
    1719             :  * between the current xas position and @max.  @entry will be set to
    1720             :  * the entry retrieved from the xarray.  It is safe to delete entries
    1721             :  * from the array in the loop body.  You should hold either the RCU lock
    1722             :  * or the xa_lock while iterating.  If you need to drop the lock, call
    1723             :  * xas_pause() first.
    1724             :  */
    1725             : #define xas_for_each(xas, entry, max) \
    1726             :         for (entry = xas_find(xas, max); entry; \
    1727             :              entry = xas_next_entry(xas, max))
    1728             : 
    1729             : /**
    1730             :  * xas_for_each_marked() - Iterate over a range of an XArray.
    1731             :  * @xas: XArray operation state.
    1732             :  * @entry: Entry retrieved from the array.
    1733             :  * @max: Maximum index to retrieve from array.
    1734             :  * @mark: Mark to search for.
    1735             :  *
    1736             :  * The loop body will be executed for each marked entry in the xarray
    1737             :  * between the current xas position and @max.  @entry will be set to
    1738             :  * the entry retrieved from the xarray.  It is safe to delete entries
    1739             :  * from the array in the loop body.  You should hold either the RCU lock
    1740             :  * or the xa_lock while iterating.  If you need to drop the lock, call
    1741             :  * xas_pause() first.
    1742             :  */
    1743             : #define xas_for_each_marked(xas, entry, max, mark) \
    1744             :         for (entry = xas_find_marked(xas, max, mark); entry; \
    1745             :              entry = xas_next_marked(xas, max, mark))
    1746             : 
    1747             : /**
    1748             :  * xas_for_each_conflict() - Iterate over a range of an XArray.
    1749             :  * @xas: XArray operation state.
    1750             :  * @entry: Entry retrieved from the array.
    1751             :  *
    1752             :  * The loop body will be executed for each entry in the XArray that
    1753             :  * lies within the range specified by @xas.  If the loop terminates
    1754             :  * normally, @entry will be %NULL.  The user may break out of the loop,
    1755             :  * which will leave @entry set to the conflicting entry.  The caller
    1756             :  * may also call xa_set_err() to exit the loop while setting an error
    1757             :  * to record the reason.
    1758             :  */
    1759             : #define xas_for_each_conflict(xas, entry) \
    1760             :         while ((entry = xas_find_conflict(xas)))
    1761             : 
    1762             : void *__xas_next(struct xa_state *);
    1763             : void *__xas_prev(struct xa_state *);
    1764             : 
    1765             : /**
    1766             :  * xas_prev() - Move iterator to previous index.
    1767             :  * @xas: XArray operation state.
    1768             :  *
    1769             :  * If the @xas was in an error state, it will remain in an error state
    1770             :  * and this function will return %NULL.  If the @xas has never been walked,
    1771             :  * it will have the effect of calling xas_load().  Otherwise one will be
    1772             :  * subtracted from the index and the state will be walked to the correct
    1773             :  * location in the array for the next operation.
    1774             :  *
    1775             :  * If the iterator was referencing index 0, this function wraps
    1776             :  * around to %ULONG_MAX.
    1777             :  *
    1778             :  * Return: The entry at the new index.  This may be %NULL or an internal
    1779             :  * entry.
    1780             :  */
    1781           0 : static inline void *xas_prev(struct xa_state *xas)
    1782             : {
    1783           0 :         struct xa_node *node = xas->xa_node;
    1784             : 
    1785           0 :         if (unlikely(xas_not_node(node) || node->shift ||
    1786             :                                 xas->xa_offset == 0))
    1787           0 :                 return __xas_prev(xas);
    1788             : 
    1789           0 :         xas->xa_index--;
    1790           0 :         xas->xa_offset--;
    1791           0 :         return xa_entry(xas->xa, node, xas->xa_offset);
    1792             : }
    1793             : 
    1794             : /**
    1795             :  * xas_next() - Move state to next index.
    1796             :  * @xas: XArray operation state.
    1797             :  *
    1798             :  * If the @xas was in an error state, it will remain in an error state
    1799             :  * and this function will return %NULL.  If the @xas has never been walked,
    1800             :  * it will have the effect of calling xas_load().  Otherwise one will be
    1801             :  * added to the index and the state will be walked to the correct
    1802             :  * location in the array for the next operation.
    1803             :  *
    1804             :  * If the iterator was referencing index %ULONG_MAX, this function wraps
    1805             :  * around to 0.
    1806             :  *
    1807             :  * Return: The entry at the new index.  This may be %NULL or an internal
    1808             :  * entry.
    1809             :  */
    1810           0 : static inline void *xas_next(struct xa_state *xas)
    1811             : {
    1812           0 :         struct xa_node *node = xas->xa_node;
    1813             : 
    1814           0 :         if (unlikely(xas_not_node(node) || node->shift ||
    1815             :                                 xas->xa_offset == XA_CHUNK_MASK))
    1816           0 :                 return __xas_next(xas);
    1817             : 
    1818           0 :         xas->xa_index++;
    1819           0 :         xas->xa_offset++;
    1820           0 :         return xa_entry(xas->xa, node, xas->xa_offset);
    1821             : }
    1822             : 
    1823             : #endif /* _LINUX_XARRAY_H */

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