From: Ioan-Adrian Ratiu <adi@adirat.com>
To: tiwai@suse.com
Cc: linux-kernel@vger.kernel.org, alsa-devel@alsa-project.org,
perex@perex.cz
Subject: [PATCH v3 2/2] ALSA: usb-audio: test EP_FLAG_RUNNING at urb completion
Date: Thu, 5 Jan 2017 00:37:47 +0200 [thread overview]
Message-ID: <20170104223747.2742-3-adi@adirat.com> (raw)
In-Reply-To: <20170104223747.2742-1-adi@adirat.com>
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
next prev parent reply other threads:[~2017-01-04 22:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-04 22:37 [PATCH v3 0/2] ALSA: Fix usb-audio races Ioan-Adrian Ratiu
2017-01-04 22:37 ` [PATCH v3 1/2] ALSA: usb-audio: Fix irq/process data synchronization Ioan-Adrian Ratiu
2017-01-04 22:37 ` Ioan-Adrian Ratiu [this message]
2017-01-05 6:36 ` [PATCH v3 0/2] ALSA: Fix usb-audio races Takashi Iwai
2017-01-05 6:36 ` Takashi Iwai
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