ratelimit.c

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    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/ratelimit.h>
   13 #include <linux/jiffies.h>
   14 #include <linux/export.h>
   15 
   16 /*
   17  * __ratelimit - rate limiting
   18  * @rs: ratelimit_state data
   19  * @func: name of calling function
   20  *
   21  * This enforces a rate limit: not more than @rs->burst callbacks
   22  * in every @rs->interval
   23  *
   24  * RETURNS:
   25  * 0 means callbacks will be suppressed.
   26  * 1 means go ahead and do it.
   27  */
   28 int ___ratelimit(struct ratelimit_state *rs, const char *func)
   29 {
   30         unsigned long flags;
   31         int ret;
   32 
   33         if (!rs->interval)
   34                 return 1;
   35 
   36         /*
   37          * If we contend on this state's lock then almost
   38          * by definition we are too busy to print a message,
   39          * in addition to the one that will be printed by
   40          * the entity that is holding the lock already:
   41          */
   42         if (!raw_spin_trylock_irqsave(&rs->lock, flags))
   43                 return 0;
   44 
   45         if (!rs->begin)
   46                 rs->begin = jiffies;
   47 
   48         if (time_is_before_jiffies(rs->begin + rs->interval)) {
   49                 if (rs->missed)
   50                         printk(KERN_WARNING "%s: %d callbacks suppressed\n",
   51                                 func, rs->missed);
   52                 rs->begin   = 0;
   53                 rs->printed = 0;
   54                 rs->missed  = 0;
   55         }
   56         if (rs->burst && rs->burst > rs->printed) {
   57                 rs->printed++;
   58                 ret = 1;
   59         } else {
   60                 rs->missed++;
   61                 ret = 0;
   62         }
   63         raw_spin_unlock_irqrestore(&rs->lock, flags);
   64 
   65         return ret;
   66 }
   67 EXPORT_SYMBOL(___ratelimit);

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FreeBSD/Linux Kernel Cross Reference sys/lib/ratelimit.c

FreeBSD/Linux Kernel Cross Reference
sys/lib/ratelimit.c