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Sun, 30 Aug 2020 11:04:54 -0400 Received: from mail-ot1-x343.google.com (mail-ot1-x343.google.com [IPv6:2607:f8b0:4864:20::343]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 48CAAC061236; Sun, 30 Aug 2020 08:04:53 -0700 (PDT) Received: by mail-ot1-x343.google.com with SMTP id i4so270069ota.2; Sun, 30 Aug 2020 08:04:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=pMRtD6tzB0RfchkgrwI0vaPh8EOiJQaXxLNReVAOoxQ=; b=oIywOkO7Lkwid5PbB8cZGWceW9jnT9dfHQdi7ZtIXdTVRSXFVnaOMrg7SLMadALZME JJ+m1bxfgn+QY3zfwNicERjnkWt2wVP4ZcjkWP/g+jL7r7RoW992yxpcd4vIAIo7Havg 24o4uXcPGfkIx/d/sgVrMQ50b5THtqJJznnJFtmfzxSDLHutc/7rcL+q5Lb+PTwzGGds Pxuq+f/7FylqQR7/SUaoWeuPBfULol4t3p9tgZHjTVFFUekoqC94D1pXDRP3XjnEXbS4 95XOIWJ3aA1cUqkZJE7WVS2rxkma2E8yl5FJ3tKt5thOBcvoHTQda2oUDGS8d0fZK39z mWxw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references; 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RSP: 002b:00007ddebffd5c10 EFLAGS: 00000293 ORIG_RAX: 0000000000000017 RAX: fffffffffffffdfe RBX: 000000000000000a RCX: 00007ddec156dc26 RDX: 0000000000000000 RSI: 00007ddebffd5d28 RDI: 000000000000000a RBP: 00007ddebffd5c50 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 00007ddebffd5d28 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 When this was observed, a USB disconnect was in progress, uvc_disconnect() had returned, but usb_disable_device() was still running. Drivers are not supposed to call any USB functions after the driver disconnect function has been called. The uvcvideo driver does not follow that convention and tries to write to the disconnected USB interface anyway. This results in a variety of race conditions. To solve this specific problem, release the uvc queue from uvc_unregister_video() after the associated video devices have been unregistered. Since the function already holds the uvc queue mutex, bypass uvc_queue_release() and call vb2_queue_release() directly. Cc: Laurent Pinchart Cc: Alan Stern Cc: Hans Verkuil Signed-off-by: Guenter Roeck --- drivers/media/usb/uvc/uvc_driver.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c index a5808305f1e3..27b72806b9b9 100644 --- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -1955,6 +1955,8 @@ static void uvc_unregister_video(struct uvc_device *dev) uvc_debugfs_cleanup_stream(stream); + vb2_queue_release(&stream->queue.queue); + mutex_unlock(&stream->queue.mutex); mutex_unlock(&stream->mutex); }