ALSA: usb-audio: test EP_FLAG_RUNNING at urb completion

[ Upstream commit 13a6c8328e6056932dc680e447d4c5e8ad9add17 ]

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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
index c5251aa..b8044c6 100644 (file)
--- 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 */