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The ratelimit_state structure's ->missed field is sometimes incremented locklessly, and it would be good to avoid lost counts. This is also needed to count the number of misses due to trylock failure. Therefore, convert the ratelimit_state structure's ->missed field to atomic_t. Link: https://lore.kernel.org/all/fbe93a52-365e-47fe-93a4-44a44547d601@paulmck-laptop/ Link: https://lore.kernel.org/all/20250423115409.3425-1-spasswolf@web.de/ Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Kuniyuki Iwashima <kuniyu@amazon.com> Cc: Mateusz Guzik <mjguzik@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: John Ogness <john.ogness@linutronix.de> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
77 lines
1.9 KiB
C
77 lines
1.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* ratelimit.c - Do something with rate limit.
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*
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* Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
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*
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* 2008-05-01 rewrite the function and use a ratelimit_state data struct as
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* parameter. Now every user can use their own standalone ratelimit_state.
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*/
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#include <linux/ratelimit.h>
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#include <linux/jiffies.h>
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#include <linux/export.h>
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/*
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* __ratelimit - rate limiting
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* @rs: ratelimit_state data
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* @func: name of calling function
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*
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* This enforces a rate limit: not more than @rs->burst callbacks
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* in every @rs->interval
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*
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* RETURNS:
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* 0 means callbacks will be suppressed.
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* 1 means go ahead and do it.
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*/
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int ___ratelimit(struct ratelimit_state *rs, const char *func)
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{
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/* Paired with WRITE_ONCE() in .proc_handler().
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* Changing two values seperately could be inconsistent
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* and some message could be lost. (See: net_ratelimit_state).
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*/
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int interval = READ_ONCE(rs->interval);
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int burst = READ_ONCE(rs->burst);
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unsigned long flags;
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int ret;
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if (!interval)
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return 1;
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/*
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* If we contend on this state's lock then almost
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* by definition we are too busy to print a message,
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* in addition to the one that will be printed by
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* the entity that is holding the lock already:
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*/
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if (!raw_spin_trylock_irqsave(&rs->lock, flags))
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return 0;
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if (!rs->begin)
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rs->begin = jiffies;
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if (time_is_before_jiffies(rs->begin + interval)) {
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int m = ratelimit_state_reset_miss(rs);
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if (m) {
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if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
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printk_deferred(KERN_WARNING
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"%s: %d callbacks suppressed\n", func, m);
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}
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}
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rs->begin = jiffies;
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rs->printed = 0;
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}
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if (burst && burst > rs->printed) {
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rs->printed++;
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ret = 1;
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} else {
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ratelimit_state_inc_miss(rs);
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ret = 0;
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}
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raw_spin_unlock_irqrestore(&rs->lock, flags);
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return ret;
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}
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EXPORT_SYMBOL(___ratelimit);
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