[PATCH 3.12 124/170] ALSA: usb-audio: Prevent printk ratelimiting from spamming kernel log while DEBUG not defined

Jiri Slaby
2014-07-18T13:10:30Z

From: Sander Eikelenboom <linux@eikelenboom.it>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit b7a7723513dc89f83d6df13206df55d4dc26e825 upstream.

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@eikelenboom.it>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
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 d59e0c1a3e20..98ca3540514f 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -1491,9 +1491,9 @@ 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) {
--
2.0.0