Ack: [Trusty][SRU][PATCH 1/1] ALSA: usb-audio: Prevent printk ratelimiting from spamming kernel log while DEBUG not defined

[Joseph Salisbury]

On 06/18/2014 11:58 AM, Brad Figg wrote:
> On 06/18/2014 08:49 AM, Joseph Salisbury wrote:
>> From: Sander Eikelenboom <linux at eikelenboom.it>
>>
>> BugLink: http://bugs.launchpad.net/bugs/1319457
>>
>> 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 <linux at eikelenboom.it>
>> Signed-off-by: Takashi Iwai <tiwai at suse.de>
>> (backported from commit b7a7723513dc89f83d6df13206df55d4dc26e825)
>> Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
>> ---
>>  sound/usb/pcm.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
>> index 7bfa7a1..ede4b92 100644
>> --- a/sound/usb/pcm.c
>> +++ b/sound/usb/pcm.c
>> @@ -1487,9 +1487,9 @@ 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)
>> -		snd_printk(KERN_DEBUG "delay: estimated %d, actual %d\n",
>> +	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);
>>  
>>  	if (!subs->running) {
>>
> Seems like this should be coming in via stable upstream.
>
Yes, I'll be sending a request to have this included upstream as well.