linux-kernel - Re: [PACTH v2] cdc-wdm: Clear read pipeline in case of error

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Date:	Tue, 9 Aug 2016 10:22:27 -0400
From:	Robert Foss <robert.foss@...labora.com>
To:	Greg KH <gregkh@...uxfoundation.org>
Cc:	oneukum@...e.com, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, Ben Chan <benchan@...omium.org>,
	Guenter Roeck <groeck@...gle.com>,
	Prathmesh Prabhu <pprabhu@...omium.org>
Subject: Re: [PACTH v2] cdc-wdm: Clear read pipeline in case of error



On 2016-08-09 09:51 AM, Greg KH wrote:
> On Mon, Aug 08, 2016 at 11:48:52AM -0400, robert.foss@...labora.com wrote:
>> From: Robert Foss <robert.foss@...labora.com>
>>
>> Implemented queued response handling. This queue is processed every time the
>> WDM_READ flag is cleared.
>>
>> In case of a read error, userspace may not actually read the data, since the
>> driver returns an error through wdm_poll. After this, the underlying device may
>> attempt to send us more data, but the queue is not processed. While userspace is
>> also blocked, because the read error is never cleared.
>>
>> After this patch, we proactively process the queue on a read error. If there was
>> an outstanding response to handle, that will clear the error (or go through the
>> same logic again, if another read error occurs). If there was no outstanding
>> response, this will bring the queue size back to 0, unblocking a future response
>> from the underlying device.
>>
>> Tested-by: Robert Foss <robert.foss@...labora.com>
>> Signed-off-by: Robert Foss <robert.foss@...labora.com>
>> Acked-by: Oliver Neukum <oneukum@...e.com>

Thanks Oliver!

>> ---
>>
>> Changes since v1:
>> - Only set a new error code it there is no previous error code
>
> This no longer applies to my tree due to a patch sent before yours for
> the same driver.  Can you resync against my usb-testing brance on my
> usb.git tree on git.kernel.org and resend?
>

Will do!