[PATCH 5.3 15/48] ALSA: usb-audio: not submit urb for stopped endpoint

From: Greg Kroah-Hartman
Date: Tue Nov 19 2019 - 00:21:25 EST

From: Henry Lin <henryl@xxxxxxxxxx>

commit 528699317dd6dc722dccc11b68800cf945109390 upstream.

While output urb's snd_complete_urb() is executing, calling
prepare_outbound_urb() may cause endpoint stopped before
prepare_outbound_urb() returns and result in next urb submitted
to stopped endpoint. usb-audio driver cannot re-use it afterwards as
the urb is still hold by usb stack.

This change checks EP_FLAG_RUNNING flag after prepare_outbound_urb() again
to let snd_complete_urb() know the endpoint already stopped and does not
submit next urb. Below kind of error will be fixed:

[ 213.153103] usb 1-2: timeout: still 1 active urbs on EP #1
[ 213.164121] usb 1-2: cannot submit urb 0, error -16: unknown error

Signed-off-by: Henry Lin <henryl@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20191113021420.13377-1-henryl@xxxxxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

sound/usb/endpoint.c | 3 +++
1 file changed, 3 insertions(+)

--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -388,6 +388,9 @@ static void snd_complete_urb(struct urb

prepare_outbound_urb(ep, ctx);
+ /* can be stopped during prepare callback */
+ if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
+ goto exit_clear;
} else {
retire_inbound_urb(ep, ctx);
/* can be stopped during retire callback */