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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: 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>
This commit is contained in:
Borislav Petkov 2016-08-02 14:04:04 -07:00 committed by Linus Torvalds
parent b5644a153d
commit 6b1d174b0c
2 changed files with 39 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
include/linux/ratelimit.h
View File

@ -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;

10
lib/ratelimit.c
View File

@ -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++;