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


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