linux-kernel - [PATCH] usb: gadget: uvc_video: unlock before submitting a request to ep

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Message-ID: <20231102071138.828126-1-piyush.mehta@amd.com>
Date:   Thu, 2 Nov 2023 12:41:38 +0530
From:   Piyush Mehta <piyush.mehta@....com>
To:     <laurent.pinchart@...asonboard.com>, <dan.scally@...asonboard.com>,
        <michal.simek@....com>, <gregkh@...uxfoundation.org>
CC:     <siva.durga.prasad.paladugu@....com>,
        <radhey.shyam.pandey@....com>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Piyush Mehta <piyush.mehta@....com>
Subject: [PATCH] usb: gadget: uvc_video: unlock before submitting a request to ep

There could be chances where the usb_ep_queue() could fail and trigger
complete() handler with error status. In this case, if usb_ep_queue()
is called with lock held and the triggered complete() handler is waiting
for the same lock to be cleared could result in a deadlock situation and
could result in system hang. To aviod this scenerio, call usb_ep_queue()
with lock removed. This patch does the same.

Signed-off-by: Piyush Mehta <piyush.mehta@....com>
---
 drivers/usb/gadget/function/uvc_video.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/uvc_video.c b/drivers/usb/gadget/function/uvc_video.c
index 91af3b1ef0d4..0a5d9ac145e7 100644
--- a/drivers/usb/gadget/function/uvc_video.c
+++ b/drivers/usb/gadget/function/uvc_video.c
@@ -460,11 +460,12 @@ static void uvcg_video_pump(struct work_struct *work)
 			req->no_interrupt = 1;
 		}
 
-		/* Queue the USB request */
-		ret = uvcg_video_ep_queue(video, req);
 		spin_unlock_irqrestore(&queue->irqlock, flags);
 
+		/* Queue the USB request */
+		ret = uvcg_video_ep_queue(video, req);
 		if (ret < 0) {
+			usb_ep_set_halt(video->ep);
 			uvcg_queue_cancel(queue, 0);
 			break;
 		}
-- 
2.25.1