linux-kernel - [PATCH 4.4 004/159] ALSA: usb-audio: not submit urb for stopped endpoint

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Message-Id: <20191122100708.764223290@linuxfoundation.org>
Date:   Fri, 22 Nov 2019 11:26:35 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Henry Lin <henryl@...dia.com>,
        Takashi Iwai <tiwai@...e.de>
Subject: [PATCH 4.4 004/159] ALSA: usb-audio: not submit urb for stopped endpoint

From: Henry Lin <henryl@...dia.com>

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@...dia.com>
Cc: <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/20191113021420.13377-1-henryl@nvidia.com
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- a/sound/usb/endpoint.c
+++ b/sound/usb/endpoint.c
@@ -403,6 +403,9 @@ 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 */