2 * ratelimit.c - Do something with rate limit.
4 * Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
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.
9 * This file is released under the GPLv2.
12 #include <linux/ratelimit.h>
13 #include <linux/jiffies.h>
14 #include <linux/export.h>
17 * __ratelimit - rate limiting
18 * @rs: ratelimit_state data
19 * @func: name of calling function
21 * This enforces a rate limit: not more than @rs->burst callbacks
22 * in every @rs->interval
25 * 0 means callbacks will be suppressed.
26 * 1 means go ahead and do it.
28 int ___ratelimit(struct ratelimit_state *rs, const char *func)
30 /* Paired with WRITE_ONCE() in .proc_handler().
31 * Changing two values seperately could be inconsistent
32 * and some message could be lost. (See: net_ratelimit_state).
34 int interval = READ_ONCE(rs->interval);
35 int burst = READ_ONCE(rs->burst);
43 * If we contend on this state's lock then almost
44 * by definition we are too busy to print a message,
45 * in addition to the one that will be printed by
46 * the entity that is holding the lock already:
48 if (!raw_spin_trylock_irqsave(&rs->lock, flags))
54 if (time_is_before_jiffies(rs->begin + interval)) {
56 if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
57 printk_deferred(KERN_WARNING
58 "%s: %d callbacks suppressed\n",
66 if (burst && burst > rs->printed) {
73 raw_spin_unlock_irqrestore(&rs->lock, flags);
77 EXPORT_SYMBOL(___ratelimit);