tree e41056adf7f00cad4681051d4b7d6b524ea8a68f
parent 9624ea812c7afd2e403c56366cadddb9ecfb88c6
author Clemens Ladisch <[EMAIL PROTECTED]> Mon, 15 Aug 2005 08:25:50 +0200
committer Jaroslav Kysela <[EMAIL PROTECTED]> Tue, 30 Aug 2005 08:45:50 +0200
[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: Clemens Ladisch <[EMAIL PROTECTED]>
sound/usb/usbaudio.c | 10 ++++++++--
1 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -815,8 +815,14 @@ static int wait_clear_urbs(snd_usb_subst
*/
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;
}
-
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