linux-kernel - Re: [PACTH v1] cdc-wdm: Clear read pipeline in case of error

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Date:	Mon, 8 Aug 2016 10:38:42 -0400
From:	Robert Foss <robert.foss@...labora.com>
To:	Oliver Neukum <oneukum@...e.com>
Cc:	Ben Chan <benchan@...omium.org>, pprabhu@...omium.org,
	Guenter Roeck <groeck@...gle.com>, gregkh@...uxfoundation.org,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PACTH v1] cdc-wdm: Clear read pipeline in case of error



On 2016-08-07 04:59 AM, Oliver Neukum wrote:
> On Thu, 2016-08-04 at 13:44 -0400, Robert Foss wrote:
>>
>> On 2016-08-03 06:39 AM, Oliver Neukum wrote:
>>> On Tue, 2016-08-02 at 10:37 -0400, Robert Foss wrote:
>
>>> How can that depend on what we return to user space?
>>> In the driver we can continue just ignoring errors.
>>> Now, if user space stops reading because we reported an error,
>>> that is the decision user space has made. We cannot ignore errors
>>> in the kernel because we don't like what user space does when it
>>> sees the error.
>>
>> So perhaps the better solution is to be more intelligent about how
>> desc->rerr is written to during after an error to be able to maintain
>> the error condition?
>
> Yes, good idea. I think an error condition should never be overwritten.
> So we go to the current behaviour only if a second error before
> user space has seen the3 first error arises. Would that fix your
> issue?

Excellent!

As long as the device is able to keep pushing data during an -EPIPE 
error condition, I think my issues would be solved.