linux-kernel - Re: [PATCH 2/2] usb: host: xhci: Handle the right timeout command

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Date:   Mon, 2 Jan 2017 16:57:37 +0200
From:   Mathias Nyman <mathias.nyman@...ux.intel.com>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        USB <linux-usb@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Mark Brown <broonie@...nel.org>,
        "Lu, Baolu" <baolu.lu@...el.com>
Subject: Re: [PATCH 2/2] usb: host: xhci: Handle the right timeout command

On 27.12.2016 05:07, Baolin Wang wrote:
> Hi,
>
> On 21 December 2016 at 21:00, Mathias Nyman
> <mathias.nyman@...ux.intel.com> wrote:
>> On 21.12.2016 04:22, Baolin Wang wrote:
>>>
>>> Hi Mathias,
>>>
>>> On 20 December 2016 at 23:13, Mathias Nyman
>>> <mathias.nyman@...ux.intel.com> wrote:
>>>>
>>>> On 20.12.2016 09:30, Baolin Wang wrote:
>>>> ...
>>>>
>>>> Alright, I gathered all current work related to xhci races and timeouts
>>>> and put them into a branch:
>>>>
>>>> git://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git
>>>> timeout_race_fixes
>>>>
>>>> Its based on 4.9
>>>> It includes a few other patches just to avoid conflicts and  make my life
>>>> easier
>>>>
>>>> Interesting patches are:
>>>>
>>>> ee4eb91 xhci: remove unnecessary check for pending timer
>>>> 0cba67d xhci: detect stop endpoint race using pending timer instead of
>>>> counter.
>>>> 4f2535f xhci: Handle command completion and timeout race
>>>> b9d00d7 usb: host: xhci: Fix possible wild pointer when handling abort
>>>> command
>>>> 529a5a0 usb: xhci: fix possible wild pointer
>>>> 4766555 xhci: Fix race related to abort operation
>>>> de834a3 xhci: Use delayed_work instead of timer for command timeout
>>>> 69973b8 Linux 4.9
>>>>
>>>> The fixes for command queue races will go to usb-linus and stable, the
>>>> reworks for stop ep watchdog timer will go to usb-next.
>>>
>>>
>>> How about applying below patch in your 'timeout_race_fixes' branch?
>>> [PATCH] usb: host: xhci: Clean up commands when stop endpoint command is
>>> timeout
>>> https://lkml.org/lkml/2016/12/13/94
>>>
>>
>> usb_hc_died() should eventyally end up calling xhci_mem_cleanup()
>> which will cleanup the command queue. But I need to look into that
>
> usb_hc_died() did not call xhci_mem_cleanup() to clean up command
> queue, it just disconnects all children devices attached on the dying
> hub. I did not find where it will clean up the command queue when
> issuing usb_hc_died(). Also before issuing usb_hc_died() in
> xhci_handle_command_timeout(), we will call
> xhci_cleanup_command_queue(). I think it should same as in
> xhci_stop_endpoint_command_watchdog().
>

You're right, it doesn't call xhci_mem_cleanup.
Need to look at this after getting first series of fixes to usb-linus

-Mathias