linux-kernel - Re: [PATCH v5] usb:gadget:uvc Do not use worker thread to pump isoc usb requests

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2023110953-tavern-underwent-63e7@gregkh>
Date:   Thu, 9 Nov 2023 06:29:05 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Jayant Chowdhary <jchowdhary@...gle.com>
Cc:     dan.scally@...asonboard.com, stern@...land.harvard.edu,
        laurent.pinchart@...asonboard.com, m.grzeschik@...gutronix.de,
        Thinh.Nguyen@...opsys.com, arakesh@...gle.com, etalvala@...gle.com,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH v5] usb:gadget:uvc Do not use worker thread to pump isoc
 usb requests

On Thu, Nov 09, 2023 at 02:12:50AM +0000, Jayant Chowdhary wrote:
> When we use an async work queue to perform the function of pumping
> usb requests to the usb controller, it is possible that amongst other
> factors, thread scheduling affects at what cadence we're able to pump
> requests. This could mean isoc usb requests miss their uframes - resulting
> in video stream flickers on the host device.
> 
> To avoid this, we make the async_wq thread only produce isoc usb_requests
> with uvc buffers encoded into them. The process of queueing to the
> endpoint is done by the uvc_video_complete() handler. In case no
> usb_requests are ready with encoded information, we just queue a zero
> length request to the endpoint from the complete handler.
> 
> For bulk endpoints the async_wq thread still queues usb requests to the
> endpoint.
> 
> Change-Id: I8a33cbf83fb2f04376826185079f8b25404fe761
> Signed-off-by: Michael Grzeschik <m.grzeschik@...gutronix.de>
> Signed-off-by: Jayant Chowdhary <jchowdhary@...gle.com>
> Suggested-by: Avichal Rakesh <arakesh@...gle.com>
> Suggested-by: Alan Stern <stern@...land.harvard.edu>
> ---
>  Based on top of
>  https://lore.kernel.org/linux-usb/20230930184821.310143-1-arakesh@google.com/T/#t:
>  v1->v2: Added self Signed-Off-by and addressed review comments
>  v2->v3: Encode to usb requests in async_wq; queue to ep in complete handler
> 	 for isoc transfers.
>  v3->v4: Address review comments around code style.
>  v4->v5: Update comments. Remove 0 length request queueing from async_wq
> 	 thread since it is already done by the complete handler.

You forgot to run checkpatch.pl :(