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Commit 6b1d174b authored by Borislav Petkov's avatar Borislav Petkov Committed by Linus Torvalds
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ratelimit: extend to print suppressed messages on release 

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: default avatarBorislav 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b5644a15

include/linux/ratelimit.h

+33 −5
Original line number Diff line number Diff line
@@ -2,11 +2,15 @@ 
#define _LINUX_RATELIMIT_H



#include <linux/param.h>

#include <linux/sched.h>

#include <linux/spinlock.h>



#define DEFAULT_RATELIMIT_INTERVAL	(5 * HZ)

#define DEFAULT_RATELIMIT_BURST		10



/* issue num suppressed message on exit */

#define RATELIMIT_MSG_ON_RELEASE	BIT(0)



struct ratelimit_state {

	raw_spinlock_t	lock;		/* protect the state */
@@ -15,6 +19,7 @@ struct ratelimit_state { 
	int		printed;

	int		missed;

	unsigned long	begin;

	unsigned long	flags;

};



#define RATELIMIT_STATE_INIT(name, interval_init, burst_init) {		\
@@ -34,12 +39,35 @@ struct ratelimit_state { 
static inline void ratelimit_state_init(struct ratelimit_state *rs,

					int interval, int burst)

{

	memset(rs, 0, sizeof(*rs));



	raw_spin_lock_init(&rs->lock);

	rs->interval	= interval;

	rs->burst	= burst;

	rs->printed = 0;

}



static inline void ratelimit_default_init(struct ratelimit_state *rs)

{

	return ratelimit_state_init(rs, DEFAULT_RATELIMIT_INTERVAL,

					DEFAULT_RATELIMIT_BURST);

}



static inline void ratelimit_state_exit(struct ratelimit_state *rs)

{

	if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE))

		return;



	if (rs->missed) {

		pr_warn("%s: %d output lines suppressed due to ratelimiting\n",

			current->comm, rs->missed);

		rs->missed = 0;

	rs->begin = 0;

	}

}



static inline void

ratelimit_set_flags(struct ratelimit_state *rs, unsigned long flags)

{

	rs->flags = flags;

}



extern struct ratelimit_state printk_ratelimit_state;

lib/ratelimit.c

+6 −4
Original line number Diff line number Diff line
@@ -46,12 +46,14 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func) 
		rs->begin = jiffies;



	if (time_is_before_jiffies(rs->begin + rs->interval)) {

		if (rs->missed)

			printk(KERN_WARNING "%s: %d callbacks suppressed\n",

				func, rs->missed);

		if (rs->missed) {

			if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {

				pr_warn("%s: %d callbacks suppressed\n", func, rs->missed);

				rs->missed = 0;

			}

		}

		rs->begin   = jiffies;

		rs->printed = 0;

		rs->missed  = 0;

	}

	if (rs->burst && rs->burst > rs->printed) {

		rs->printed++;