From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753742AbaEBQ1e (ORCPT ); Fri, 2 May 2014 12:27:34 -0400 Received: from vserver.eikelenboom.it ([84.200.39.61]:51828 "EHLO smtp.eikelenboom.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753746AbaEBQZg (ORCPT ); Fri, 2 May 2014 12:25:36 -0400 Date: Fri, 2 May 2014 18:25:30 +0200 From: Sander Eikelenboom Organization: Eikelenboom IT services X-Priority: 3 (Normal) Message-ID: <80394451.20140502182530@eikelenboom.it> To: Takashi Iwai CC: Greg Kroah-Hartman , Julia Lawall , , linux-kernel Subject: Re: [PATCH] Sound USB: Prevent printk ratelimiting from spamming kernel log while DEBUG not defined In-Reply-To: References: <1399036167-6203-1-git-send-email-linux@eikelenboom.it> <1399036167-6203-2-git-send-email-linux@eikelenboom.it> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Friday, May 2, 2014, 6:13:09 PM, you wrote: > At Fri, 2 May 2014 15:09:27 +0200, > Sander Eikelenboom wrote: >> >> This (widely used) construction: >> >> if(printk_ratelimit()) >> dev_dbg() >> >> Causes the ratelimiting to spam the kernel log with the "callbacks suppressed" >> message below, even while the dev_dbg it is supposed to rate limit wouldn't >> print anything because DEBUG is not defined for this device. >> >> [ 533.803964] retire_playback_urb: 852 callbacks suppressed >> [ 538.807930] retire_playback_urb: 852 callbacks suppressed >> [ 543.811897] retire_playback_urb: 852 callbacks suppressed >> [ 548.815745] retire_playback_urb: 852 callbacks suppressed >> [ 553.819826] retire_playback_urb: 852 callbacks suppressed >> >> So use dev_dbg_ratelimited() instead of this construction. >> >> Signed-off-by: Sander Eikelenboom > Thanks, applied. This is a result of the recent rewrite to dev_dbg() > from plain printk(), I suppose. Yes that patch (https://lkml.org/lkml/2014/4/9/457) prevented spamming the kernel log when debugging was enabled .. but now the rate limiting code starts spamming the kernel log instead :-) I must say i wasn't very aware of that effect either and also used this construction on debug patches. > Takashi >> --- >> sound/usb/pcm.c | 5 ++--- >> 1 file changed, 2 insertions(+), 3 deletions(-) >> >> diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c >> index 131336d..c62a165 100644 >> --- a/sound/usb/pcm.c >> +++ b/sound/usb/pcm.c >> @@ -1501,9 +1501,8 @@ static void retire_playback_urb(struct snd_usb_substream *subs, >> * The error should be lower than 2ms since the estimate relies >> * on two reads of a counter updated every ms. >> */ >> - if (printk_ratelimit() && >> - abs(est_delay - subs->last_delay) * 1000 > runtime->rate * 2) >> - dev_dbg(&subs->dev->dev, >> + if (abs(est_delay - subs->last_delay) * 1000 > runtime->rate * 2) >> + dev_dbg_ratelimited(&subs->dev->dev, >> "delay: estimated %d, actual %d\n", >> est_delay, subs->last_delay); >> >> -- >> 1.7.10.4 >>