linux-kernel - Re: [PATCH 2/3 v2] fb: udlfb: fix hang at disconnect

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Message-ID: <5111431D.8070906@ahsoftware.de>
Date:	Tue, 05 Feb 2013 18:36:29 +0100
From:	Alexander Holler <holler@...oftware.de>
To:	Greg KH <gregkh@...uxfoundation.org>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-fbdev@...r.kernel.org,
	Florian Tobias Schandinat <FlorianSchandinat@....de>,
	Bernie Thompson <bernie@...gable.com>,
	Steve Glendinning <steve.glendinning@...well.net>,
	stable@...r.kernel.org
Subject: Re: [PATCH 2/3 v2] fb: udlfb: fix hang at disconnect

Am 05.02.2013 18:22, schrieb Greg KH:
> On Tue, Feb 05, 2013 at 08:08:28AM +0100, Alexander Holler wrote:
>> Am 04.02.2013 20:25, schrieb Greg KH:

>>> Where was that urb when the disconnect happened?  The USB core should
>>> call your urb callback for any outstanding urbs at that point in time,
>>> with the proper error flag being set, are you handling that properly?
>>
>> I don't know where that urb is as I don't handle it.
>
> What do you mean by that?  The urb is being sent back to your driver,
> right?  If not, that's a bug, but please be sure that your urb callback
> isn't really being called.

I meant it isn't _my_ driver. ;)

I'm just trying to add some würgarounds without having the need to 
rewrite the whole driver.

In regard to that "urb missing problem", I think I've just named it 
wrong and the actual problem is a race-condition between the semaphore 
handling (which is used to keep track of the urbs) and the urb handling 
inside the driver.

But I've just switched to udl (instead of udlfb) and will see if I can 
fix the bugs there to make it usable as a console. udl is a rewrite of 
udlfb with some additional features (e.g. drm), so hopefully fixing the 
remaining problems there will require less work.

Regards,

Alexander

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