SAFE public projects git trees. - safe/jmp/linux-2.6/blob - lib/ratelimit.c

   1 /*
   2  * ratelimit.c - Do something with rate limit.
   3  *
   4  * Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
   5  *
   6  * 2008-05-01 rewrite the function and use a ratelimit_state data struct as
   7  * parameter. Now every user can use their own standalone ratelimit_state.
   8  *
   9  * This file is released under the GPLv2.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/jiffies.h>
  14 #include <linux/module.h>
  15
  16 /*
  17  * __ratelimit - rate limiting
  18  * @rs: ratelimit_state data
  19  *
  20  * This enforces a rate limit: not more than @rs->ratelimit_burst callbacks
  21  * in every @rs->ratelimit_jiffies
  22  */
  23 int __ratelimit(struct ratelimit_state *rs)
  24 {
  25         unsigned long flags;
  26         int ret;
  27
  28         if (!rs->interval)
  29                 return 1;
  30
  31         spin_lock_irqsave(&rs->lock, flags);
  32         if (!rs->begin)
  33                 rs->begin = jiffies;
  34
  35         if (time_is_before_jiffies(rs->begin + rs->interval)) {
  36                 if (rs->missed)
  37                         printk(KERN_WARNING "%s: %d callbacks suppressed\n",
  38                                 __func__, rs->missed);
  39                 rs->begin   = 0;
  40                 rs->printed = 0;
  41                 rs->missed  = 0;
  42         }
  43         if (rs->burst && rs->burst > rs->printed) {
  44                 rs->printed++;
  45                 ret = 1;
  46         } else {
  47                 rs->missed++;
  48                 ret = 0;
  49         }
  50         spin_unlock_irqrestore(&rs->lock, flags);
  51
  52         return ret;
  53 }
  54 EXPORT_SYMBOL(__ratelimit);