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Subject: Re: [PATCH 2/2] usb: host: xhci: Handle the right timeout command
To: Lu Baolu <baolu.lu@linux.intel.com>,
        OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
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Cc: Baolin Wang <baolin.wang@linaro.org>,
        Mathias Nyman <mathias.nyman@intel.com>,
        Greg KH <gregkh@linuxfoundation.org>, USB <linux-usb@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, Mark Brown <broonie@kernel.org>,
        "Lu, Baolu" <baolu.lu@intel.com>,
        Alan Stern <stern@rowland.harvard.edu>
From: Mathias Nyman <mathias.nyman@linux.intel.com>
Message-ID: <585D1E94.6040400@linux.intel.com>
Date: Fri, 23 Dec 2016 14:54:44 +0200
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On 22.12.2016 03:46, Lu Baolu wrote:
> Hi,
>
> On 12/21/2016 11:18 PM, OGAWA Hirofumi wrote:
>> Mathias Nyman <mathias.nyman@linux.intel.com> writes:
>>
>>>> We set CMD_RING_STATE_ABORTED state under locking. I'm not checking what
>>>> is for taking lock for register though, I guess it should be enough just
>>>> lock around of read=>write of ->cmd_ring if need lock.
>>> After your patch it should be enough to have the lock only while
>>> reading and writing the cmd_ring register.
>>>
>>> If we want a locking fix that applies more easily to older stable
>>> releases before your change then the lock needs to cover set
>>> CMD_RING_STATE_ABORT, read cmd_reg, write cmd_reg and busiloop
>>> checking CRR bit.  Otherwise the stop cmd ring interrupt handler may
>>> restart the ring just before we start checing CRR. The stop cmd ring
>>> interrupt will set the CMD_RING_STATE_ABORTED to
>>> CMD_RING_STATE_RUNNING so ring will really restart in the interrupt
>>> handler.
>> Just for record (no chance to make patch I myself for now, sorry), while
>> checking locking slightly, I noticed unrelated missing locking.
>>
>> 	xhci_cleanup_command_queue()
>>
>> We are calling it without locking, but we need to lock for accessing list.
>
> Yeah. I can make the patch.
>

Force updated timeout_race_fixes branch.

I'll be out for a few days during xmas, continue testing after that

-Mathias