From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753994Ab3A2PwE (ORCPT ); Tue, 29 Jan 2013 10:52:04 -0500 Received: from h1446028.stratoserver.net ([85.214.92.142]:47368 "EHLO mail.ahsoftware.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752022Ab3A2PwA (ORCPT ); Tue, 29 Jan 2013 10:52:00 -0500 Message-ID: <5107F014.4030704@ahsoftware.de> Date: Tue, 29 Jan 2013 16:51:48 +0100 From: Alexander Holler User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Andrew Morton CC: linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, Florian Tobias Schandinat , Bernie Thompson , Steve Glendinning , stable@vger.kernel.org Subject: Re: [PATCH 2/3 v2] fb: udlfb: fix hang at disconnect References: <50F2A310.5010006@ahsoftware.de> <1359139768-32294-1-git-send-email-holler@ahsoftware.de> <1359139768-32294-2-git-send-email-holler@ahsoftware.de> <20130128162238.7fba92fe.akpm@linux-foundation.org> <51071E21.9030008@ahsoftware.de> <5107A5ED.7020009@ahsoftware.de> <5107AE4F.9000809@ahsoftware.de> In-Reply-To: <5107AE4F.9000809@ahsoftware.de> Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 29.01.2013 12:11, schrieb Alexander Holler: > > To explain the problem on shutdown a bit further, I think the following > happens (usb and driver are statically linked and started by the kernel): > > shutdown -> kill signal -> usb stack shuts down -> udlfb waits (forever) > for a kill or an urb which it doesn't get. Having a second look at what I've written above, I'm not even sure if the kernel sends one or more fatal signals on shutdown at all. I've just assumed it because otherwise down_interruptible() wouldn't have worked before (it would have stalled on shutdown too (if an urb got missed), not only on disconnect). Sounds like an interesting question I should read about (if/when fatal signals are issued by the kernel). ;) > Maybe the sequence is different if the usb-stack and udlfb are used as a > module and/or udlfb is used only for X/fb. I'm not sure what actually > does shut down the usb-stack in such a case, but maybe more than one > kill signal might be thrown around. Regards, Alexander From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Holler Date: Tue, 29 Jan 2013 15:51:48 +0000 Subject: Re: [PATCH 2/3 v2] fb: udlfb: fix hang at disconnect Message-Id: <5107F014.4030704@ahsoftware.de> List-Id: References: <50F2A310.5010006@ahsoftware.de> <1359139768-32294-1-git-send-email-holler@ahsoftware.de> <1359139768-32294-2-git-send-email-holler@ahsoftware.de> <20130128162238.7fba92fe.akpm@linux-foundation.org> <51071E21.9030008@ahsoftware.de> <5107A5ED.7020009@ahsoftware.de> <5107AE4F.9000809@ahsoftware.de> In-Reply-To: <5107AE4F.9000809@ahsoftware.de> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, Florian Tobias Schandinat , Bernie Thompson , Steve Glendinning , stable@vger.kernel.org Am 29.01.2013 12:11, schrieb Alexander Holler: > > To explain the problem on shutdown a bit further, I think the following > happens (usb and driver are statically linked and started by the kernel): > > shutdown -> kill signal -> usb stack shuts down -> udlfb waits (forever) > for a kill or an urb which it doesn't get. Having a second look at what I've written above, I'm not even sure if the kernel sends one or more fatal signals on shutdown at all. I've just assumed it because otherwise down_interruptible() wouldn't have worked before (it would have stalled on shutdown too (if an urb got missed), not only on disconnect). Sounds like an interesting question I should read about (if/when fatal signals are issued by the kernel). ;) > Maybe the sequence is different if the usb-stack and udlfb are used as a > module and/or udlfb is used only for X/fb. I'm not sure what actually > does shut down the usb-stack in such a case, but maybe more than one > kill signal might be thrown around. Regards, Alexander