From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934191AbcATOhP (ORCPT ); Wed, 20 Jan 2016 09:37:15 -0500 Received: from mail-pa0-f54.google.com ([209.85.220.54]:33708 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751367AbcATOhL (ORCPT ); Wed, 20 Jan 2016 09:37:11 -0500 From: Jaewon Kim To: akpm@linux-foundation.org, linux-kernel@vger.kernel.org Cc: Jaewon Kim Subject: [PATCH] ratelimit: fix bug in time interval by resetting right begin time Date: Wed, 20 Jan 2016 23:36:53 +0900 Message-Id: <1453300613-2701-1-git-send-email-jaewon31.kim@gmail.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org rs->begin in ratelimit is set in two cases. 1) when rs->begin was not initialized 2) when rs->interval was passed For the 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 --- lib/ratelimit.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/ratelimit.c b/lib/ratelimit.c index 40e03ea..2c5de86 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; } -- 1.9.1