Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0-or-later */
       2             : /*
       3             :  * Queued spinlock
       4             :  *
       5             :  * (C) Copyright 2013-2015 Hewlett-Packard Development Company, L.P.
       6             :  * (C) Copyright 2015 Hewlett-Packard Enterprise Development LP
       7             :  *
       8             :  * Authors: Waiman Long <waiman.long@hpe.com>
       9             :  */
      10             : #ifndef __ASM_GENERIC_QSPINLOCK_H
      11             : #define __ASM_GENERIC_QSPINLOCK_H
      12             : 
      13             : #include <asm-generic/qspinlock_types.h>
      14             : #include <linux/atomic.h>
      15             : 
      16             : #ifndef queued_spin_is_locked
      17             : /**
      18             :  * queued_spin_is_locked - is the spinlock locked?
      19             :  * @lock: Pointer to queued spinlock structure
      20             :  * Return: 1 if it is locked, 0 otherwise
      21             :  */
      22     9106308 : static __always_inline int queued_spin_is_locked(struct qspinlock *lock)
      23             : {
      24             :         /*
      25             :          * Any !0 state indicates it is locked, even if _Q_LOCKED_VAL
      26             :          * isn't immediately observable.
      27             :          */
      28     9104733 :         return atomic_read(&lock->val);
      29             : }
      30             : #endif
      31             : 
      32             : /**
      33             :  * queued_spin_value_unlocked - is the spinlock structure unlocked?
      34             :  * @lock: queued spinlock structure
      35             :  * Return: 1 if it is unlocked, 0 otherwise
      36             :  *
      37             :  * N.B. Whenever there are tasks waiting for the lock, it is considered
      38             :  *      locked wrt the lockref code to avoid lock stealing by the lockref
      39             :  *      code and change things underneath the lock. This also allows some
      40             :  *      optimizations to be applied without conflict with lockref.
      41             :  */
      42             : static __always_inline int queued_spin_value_unlocked(struct qspinlock lock)
      43             : {
      44             :         return !atomic_read(&lock.val);
      45             : }
      46             : 
      47             : /**
      48             :  * queued_spin_is_contended - check if the lock is contended
      49             :  * @lock : Pointer to queued spinlock structure
      50             :  * Return: 1 if lock contended, 0 otherwise
      51             :  */
      52             : static __always_inline int queued_spin_is_contended(struct qspinlock *lock)
      53             : {
      54             :         return atomic_read(&lock->val) & ~_Q_LOCKED_MASK;
      55             : }
      56             : /**
      57             :  * queued_spin_trylock - try to acquire the queued spinlock
      58             :  * @lock : Pointer to queued spinlock structure
      59             :  * Return: 1 if lock acquired, 0 if failed
      60             :  */
      61       26795 : static __always_inline int queued_spin_trylock(struct qspinlock *lock)
      62             : {
      63       26795 :         int val = atomic_read(&lock->val);
      64             : 
      65       26807 :         if (unlikely(val))
      66             :                 return 0;
      67             : 
      68       52582 :         return likely(atomic_try_cmpxchg_acquire(&lock->val, &val, _Q_LOCKED_VAL));
      69             : }
      70             : 
      71             : extern void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
      72             : 
      73             : #ifndef queued_spin_lock
      74             : /**
      75             :  * queued_spin_lock - acquire a queued spinlock
      76             :  * @lock: Pointer to queued spinlock structure
      77             :  */
      78     9486997 : static __always_inline void queued_spin_lock(struct qspinlock *lock)
      79             : {
      80     9486997 :         int val = 0;
      81             : 
      82    19019270 :         if (likely(atomic_try_cmpxchg_acquire(&lock->val, &val, _Q_LOCKED_VAL)))
      83     9153017 :                 return;
      84             : 
      85      379256 :         queued_spin_lock_slowpath(lock, val);
      86             : }
      87             : #endif
      88             : 
      89             : #ifndef queued_spin_unlock
      90             : /**
      91             :  * queued_spin_unlock - release a queued spinlock
      92             :  * @lock : Pointer to queued spinlock structure
      93             :  */
      94             : static __always_inline void queued_spin_unlock(struct qspinlock *lock)
      95             : {
      96             :         /*
      97             :          * unlock() needs release semantics:
      98             :          */
      99             :         smp_store_release(&lock->locked, 0);
     100             : }
     101             : #endif
     102             : 
     103             : #ifndef virt_spin_lock
     104             : static __always_inline bool virt_spin_lock(struct qspinlock *lock)
     105             : {
     106             :         return false;
     107             : }
     108             : #endif
     109             : 
     110             : /*
     111             :  * Remapping spinlock architecture specific functions to the corresponding
     112             :  * queued spinlock functions.
     113             :  */
     114             : #define arch_spin_is_locked(l)          queued_spin_is_locked(l)
     115             : #define arch_spin_is_contended(l)       queued_spin_is_contended(l)
     116             : #define arch_spin_value_unlocked(l)     queued_spin_value_unlocked(l)
     117             : #define arch_spin_lock(l)               queued_spin_lock(l)
     118             : #define arch_spin_trylock(l)            queued_spin_trylock(l)
     119             : #define arch_spin_unlock(l)             queued_spin_unlock(l)
     120             : 
     121             : #endif /* __ASM_GENERIC_QSPINLOCK_H */