tree 09b1710a8962d9658a95f6ede5e28b228e60838b
parent 16fd0fe4aa92d0d621ecfe21de86f7fdcfa41947
author Jaewon Kim <jaewon31.kim@samsung.com> 1453424107 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> 1453425651 -0800

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>