linux-kernel - Re: [PATCH 4/6] usbip: fix stub_dev usbip_sockfd

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Message-ID: <30a1afb2-d5a4-40b2-385d-24a2bf110e92@linuxfoundation.org>
Date:   Tue, 9 Mar 2021 12:50:41 -0700
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        shuah@...nel.org, valentina.manea.m@...il.com,
        gregkh@...uxfoundation.org
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH 4/6] usbip: fix stub_dev usbip_sockfd_store() races
 leading to gpf

On 3/9/21 4:04 AM, Tetsuo Handa wrote:
> On 2021/03/09 1:27, Shuah Khan wrote:
>> Yes. We might need synchronization between events, threads, and shutdown
>> in usbip_host side and in connection polling and threads in vhci.
>>
>> I am also looking at the shutdown sequences closely as well since the
>> local state is referenced without usbip_device lock in these paths.
>>
>> I am approaching these problems as peeling the onion an expression so
>> we can limit the changes and take a spot fix approach. We have the
>> goal to address these crashes and not introduce regressions.
> 
> I think my [PATCH v4 01/12]-[PATCH v4 06/12] simplify your further changes
> without introducing regressions. While ud->lock is held when checking ud->status,
> current attach/detach code is racy about read/update of ud->status . I think we
> can close race in attach/detach code via a simple usbip_event_mutex serialization.
> 

Do you mean patches 1,2,3,3,4,5,6?

thanks,
-- Shuah