linux-kernel - Re: [PATCH v2] usb: gadget: udc: core: Offload usb_udc_vbus

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: <c181c8ef-f342-4a31-9b8c-e1fa14ad214e@rowland.harvard.edu>
Date:   Fri, 19 May 2023 10:49:49 -0400
From:   Alan Stern <stern@...land.harvard.edu>
To:     Badhri Jagan Sridharan <badhri@...gle.com>
Cc:     gregkh@...uxfoundation.org, colin.i.king@...il.com,
        xuetao09@...wei.com, quic_eserrao@...cinc.com,
        water.zhangjiantao@...wei.com, peter.chen@...escale.com,
        balbi@...com, francesco@...cini.it, alistair@...stair23.me,
        stephan@...hold.net, bagasdotme@...il.com, luca@...tu.xyz,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org,
        Francesco Dolcini <francesco.dolcini@...adex.com>
Subject: Re: [PATCH v2] usb: gadget: udc: core: Offload usb_udc_vbus_handler
 processing

On Fri, May 19, 2023 at 04:30:41AM +0000, Badhri Jagan Sridharan wrote:
> chipidea udc calls usb_udc_vbus_handler from udc_start gadget
> ops causing a deadlock. Avoid this by offloading usb_udc_vbus_handler
> processing.

Look, this is way overkill.

usb_udc_vbus_handler() has only two jobs to do: set udc->vbus and call 
usb_udc_connect_control().  Furthermore, it gets called from only two 
drivers: chipidea and max3420.

Why not have the callers set udc->vbus themselves and then call 
usb_gadget_{dis}connect() directly?  Then we could eliminate 
usb_udc_vbus_handler() entirely.  And the unnecessary calls -- the ones 
causing deadlocks -- from within udc_start() and udc_stop() handlers can 
be removed with no further consequence.

This approach simplifies and removes code.  Whereas your approach 
complicates and adds code for no good reason.

Alan Stern