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6b1d174b0c
Extend the ratelimiting facility to print the amount of suppressed lines when it is being released. This use case is aimed at short-termed, burst-like users for which we want to output the suppressed lines stats only once, after it has been disposed of. For an example, see /dev/kmsg usage in a follow-on patch. Also, change the printk() line we issue on release to not use "callbacks" as it is misleading: we're not suppressing callbacks but printk() calls. This has been separated from a previous patch by Linus. Link: http://lkml.kernel.org/r/20160716061745.15795-2-bp@alien8.de Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Dave Young <dyoung@redhat.com> Cc: Franck Bui <fbui@suse.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
69 lines
1.6 KiB
C
69 lines
1.6 KiB
C
/*
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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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* This file is released under the GPLv2.
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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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unsigned long flags;
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int ret;
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if (!rs->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 + rs->interval)) {
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if (rs->missed) {
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if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
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pr_warn("%s: %d callbacks suppressed\n", func, rs->missed);
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rs->missed = 0;
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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 (rs->burst && rs->burst > rs->printed) {
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rs->printed++;
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ret = 1;
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} else {
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rs->missed++;
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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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