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Groups > linux.kernel > #1551461
| From | Ioan-Adrian Ratiu <adi@adirat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH v3 2/2] ALSA: usb-audio: test EP_FLAG_RUNNING at urb completion |
| Date | 2017-01-04 23:40 +0100 |
| Message-ID | <sW2nU-2uu-43@gated-at.bofh.it> (permalink) |
| References | <sW2nT-2uu-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Testing EP_FLAG_RUNNING in snd_complete_urb() before running the completion
logic allows us to save a few cpu cycles by returning early, skipping the
pending urb in case the stream was stopped; the stop logic handles the urb
and sets the completion callbacks to NULL.
Signed-off-by: Ioan-Adrian Ratiu <adi@adirat.com>
---
sound/usb/endpoint.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index 2f0ea70a998c..c90607ebe155 100644
--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -384,6 +384,9 @@ static void snd_complete_urb(struct urb *urb)
if (unlikely(atomic_read(&ep->chip->shutdown)))
goto exit_clear;
+ if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
+ goto exit_clear;
+
if (usb_pipeout(ep->pipe)) {
retire_outbound_urb(ep, ctx);
/* can be stopped during retire callback */
--
2.11.0
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[PATCH v3 0/2] ALSA: Fix usb-audio races Ioan-Adrian Ratiu <adi@adirat.com> - 2017-01-04 23:40 +0100 [PATCH v3 2/2] ALSA: usb-audio: test EP_FLAG_RUNNING at urb completion Ioan-Adrian Ratiu <adi@adirat.com> - 2017-01-04 23:40 +0100 [PATCH v3 1/2] ALSA: usb-audio: Fix irq/process data synchronization Ioan-Adrian Ratiu <adi@adirat.com> - 2017-01-04 23:40 +0100 Re: [PATCH v3 0/2] ALSA: Fix usb-audio races Takashi Iwai <tiwai@suse.de> - 2017-01-05 07:40 +0100
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