Line data    Source code

       1             : // SPDX-License-Identifier: GPL-2.0-only
       2             : /*
       3             :  * ratelimit.c - Do something with rate limit.
       4             :  *
       5             :  * Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
       6             :  *
       7             :  * 2008-05-01 rewrite the function and use a ratelimit_state data struct as
       8             :  * parameter. Now every user can use their own standalone ratelimit_state.
       9             :  */
      10             : 
      11             : #include <linux/ratelimit.h>
      12             : #include <linux/jiffies.h>
      13             : #include <linux/export.h>
      14             : 
      15             : /*
      16             :  * __ratelimit - rate limiting
      17             :  * @rs: ratelimit_state data
      18             :  * @func: name of calling function
      19             :  *
      20             :  * This enforces a rate limit: not more than @rs->burst callbacks
      21             :  * in every @rs->interval
      22             :  *
      23             :  * RETURNS:
      24             :  * 0 means callbacks will be suppressed.
      25             :  * 1 means go ahead and do it.
      26             :  */
      27          53 : int ___ratelimit(struct ratelimit_state *rs, const char *func)
      28             : {
      29          53 :         unsigned long flags;
      30          53 :         int ret;
      31             : 
      32          53 :         if (!rs->interval)
      33             :                 return 1;
      34             : 
      35             :         /*
      36             :          * If we contend on this state's lock then almost
      37             :          * by definition we are too busy to print a message,
      38             :          * in addition to the one that will be printed by
      39             :          * the entity that is holding the lock already:
      40             :          */
      41         104 :         if (!raw_spin_trylock_irqsave(&rs->lock, flags))
      42           0 :                 return 0;
      43             : 
      44          52 :         if (!rs->begin)
      45           6 :                 rs->begin = jiffies;
      46             : 
      47          52 :         if (time_is_before_jiffies(rs->begin + rs->interval)) {
      48           0 :                 if (rs->missed) {
      49           0 :                         if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
      50           0 :                                 printk_deferred(KERN_WARNING
      51             :                                                 "%s: %d callbacks suppressed\n",
      52             :                                                 func, rs->missed);
      53           0 :                                 rs->missed = 0;
      54             :                         }
      55             :                 }
      56           0 :                 rs->begin   = jiffies;
      57           0 :                 rs->printed = 0;
      58             :         }
      59          52 :         if (rs->burst && rs->burst > rs->printed) {
      60          15 :                 rs->printed++;
      61          15 :                 ret = 1;
      62             :         } else {
      63          37 :                 rs->missed++;
      64          37 :                 ret = 0;
      65             :         }
      66          52 :         raw_spin_unlock_irqrestore(&rs->lock, flags);
      67             : 
      68          52 :         return ret;
      69             : }
      70             : EXPORT_SYMBOL(___ratelimit);