Commit c2594bc3 authored by Jaewon Kim's avatar Jaewon Kim Committed by Linus Torvalds

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);

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: default avatarJaewon Kim <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 16fd0fe4
......@@ -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;
Markdown is supported
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment