The patch titled
Subject: ratelimit: extend to print suppressed messages on release
has been added to the -mm tree. Its filename is
ratelimit-extend-to-print-suppressed-messages-on-release.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ratelimit-extend-to-print-suppressed-messages-on-release.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ratelimit-extend-to-print-suppressed-messages-on-release.patch
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------------------------------------------------------
From: Borislav Petkov <bp@xxxxxxx>
Subject: 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@xxxxxxxxx
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: Franck Bui <fbui@xxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/ratelimit.h | 38 +++++++++++++++++++++++++++++++-----
lib/ratelimit.c | 10 +++++----
2 files changed, 39 insertions(+), 9 deletions(-)
diff -puN include/linux/ratelimit.h~ratelimit-extend-to-print-suppressed-messages-on-release include/linux/ratelimit.h
--- a/include/linux/ratelimit.h~ratelimit-extend-to-print-suppressed-messages-on-release
+++ a/include/linux/ratelimit.h
@@ -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;
- rs->missed = 0;
- rs->begin = 0;
+ rs->interval = interval;
+ rs->burst = burst;
+}
+
+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;
+ }
+}
+
+static inline void
+ratelimit_set_flags(struct ratelimit_state *rs, unsigned long flags)
+{
+ rs->flags = flags;
}
extern struct ratelimit_state printk_ratelimit_state;
diff -puN lib/ratelimit.c~ratelimit-extend-to-print-suppressed-messages-on-release lib/ratelimit.c
--- a/lib/ratelimit.c~ratelimit-extend-to-print-suppressed-messages-on-release
+++ a/lib/ratelimit.c
@@ -46,12 +46,14 @@ int ___ratelimit(struct ratelimit_state
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++;
_
Patches currently in -mm which might be from bp@xxxxxxx are
ratelimit-extend-to-print-suppressed-messages-on-release.patch
printk-add-kernel-parameter-to-control-writes-to-dev-kmsg.patch
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