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authorJaewon Kim <jaewon31.kim@samsung.com>2016-01-22 01:55:07 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2016-01-22 02:20:51 +0100
commitc2594bc37f4464bc74f2c119eb3269a643400aa0 (patch)
tree09b1710a8962d9658a95f6ede5e28b228e60838b /lib/ratelimit.c
parentmm: fix kernel crash in khugepaged thread (diff)
downloadlinux-c2594bc37f4464bc74f2c119eb3269a643400aa0.tar.xz
linux-c2594bc37f4464bc74f2c119eb3269a643400aa0.zip
ratelimit: fix bug in time interval by resetting right begin time
rs->begin in ratelimit is set in two cases. 1) when rs->begin was not initialized 2) when rs->interval was passed For case #2, current ratelimit sets the begin to 0. This incurrs improper suppression. The begin value will be set in the next ratelimit call by 1). Then the time interval check will be always false, and rs->printed will not be initialized. Although enough time passed, ratelimit may return 0 if rs->printed is not less than rs->burst. To reset interval properly, begin should be jiffies rather than 0. For an example code below: static DEFINE_RATELIMIT_STATE(mylimit, 1, 1); for (i = 1; i <= 10; i++) { if (__ratelimit(&mylimit)) printk("ratelimit test count %d\n", i); msleep(3000); } test result in the current code shows suppression even there is 3 seconds sleep. [ 78.391148] ratelimit test count 1 [ 81.295988] ratelimit test count 2 [ 87.315981] ratelimit test count 4 [ 93.336267] ratelimit test count 6 [ 99.356031] ratelimit test count 8 [ 105.376367] ratelimit test count 10 Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/ratelimit.c')
-rw-r--r--lib/ratelimit.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/ratelimit.c b/lib/ratelimit.c
index 40e03ea2a967..2c5de86460c5 100644
--- a/lib/ratelimit.c
+++ b/lib/ratelimit.c
@@ -49,7 +49,7 @@ int ___ratelimit(struct ratelimit_state *rs, const char *func)
if (rs->missed)
printk(KERN_WARNING "%s: %d callbacks suppressed\n",
func, rs->missed);
- rs->begin = 0;
+ rs->begin = jiffies;
rs->printed = 0;
rs->missed = 0;
}