Commit daa150ef authored by Clemens Ladisch's avatar Clemens Ladisch Committed by Jaroslav Kysela
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[ALSA] usb-audio: properly lock hwptr_done accesses 



USB generic driver
Take the substream lock when reading hwptr_done to avoid a race
condition with the updates in the URB callbacks.

Signed-off-by: default avatarClemens Ladisch <clemens@ladisch.de>
parent 9624ea81

sound/usb/usbaudio.c

+8 −2
Original line number Diff line number Diff line
@@ -815,8 +815,14 @@ static int wait_clear_urbs(snd_usb_substream_t *subs) 
 */

static snd_pcm_uframes_t snd_usb_pcm_pointer(snd_pcm_substream_t *substream)

{

	snd_usb_substream_t *subs = (snd_usb_substream_t *)substream->runtime->private_data;

	return subs->hwptr_done;

	snd_usb_substream_t *subs;

	snd_pcm_uframes_t hwptr_done;

	

	subs = (snd_usb_substream_t *)substream->runtime->private_data;

	spin_lock(&subs->lock);

	hwptr_done = subs->hwptr_done;

	spin_unlock(&subs->lock);

	return hwptr_done;

}