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From: Alexander Holler <holler@ahsoftware.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org,
	Florian Tobias Schandinat <FlorianSchandinat@gmx.de>,
	Bernie Thompson <bernie@plugable.com>,
	Steve Glendinning <steve.glendinning@shawell.net>,
	stable@vger.kernel.org
Subject: Re: [PATCH 2/3 v2] fb: udlfb: fix hang at disconnect
Date: Tue, 29 Jan 2013 16:51:48 +0100	[thread overview]
Message-ID: <5107F014.4030704@ahsoftware.de> (raw)
In-Reply-To: <5107AE4F.9000809@ahsoftware.de>

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

WARNING: multiple messages have this Message-ID (diff)
From: Alexander Holler <holler@ahsoftware.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org,
	Florian Tobias Schandinat <FlorianSchandinat@gmx.de>,
	Bernie Thompson <bernie@plugable.com>,
	Steve Glendinning <steve.glendinning@shawell.net>,
	stable@vger.kernel.org
Subject: Re: [PATCH 2/3 v2] fb: udlfb: fix hang at disconnect
Date: Tue, 29 Jan 2013 15:51:48 +0000	[thread overview]
Message-ID: <5107F014.4030704@ahsoftware.de> (raw)
In-Reply-To: <5107AE4F.9000809@ahsoftware.de>

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

  reply	other threads:[~2013-01-29 15:52 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-01-12 13:20 [PATCH] fb: udlfb: fix hang at disconnect Alexander Holler
2013-01-12 13:20 ` Alexander Holler
2013-01-12 22:22 ` Bernie Thompson
2013-01-12 22:22   ` Bernie Thompson
2013-01-13 12:05   ` Alexander Holler
2013-01-13 12:05     ` Alexander Holler
2013-01-13 12:24     ` Alexander Holler
2013-01-13 12:24       ` Alexander Holler
2013-01-25 18:49     ` [PATCH 1/3] semaphore: introduce down_timeout_killable() Alexander Holler
2013-01-25 18:49       ` Alexander Holler
2013-01-25 18:49       ` [PATCH 2/3 v2] fb: udlfb: fix hang at disconnect Alexander Holler
2013-01-25 18:49         ` Alexander Holler
2013-01-29  0:22         ` Andrew Morton
2013-01-29  0:22           ` Andrew Morton
2013-01-29  0:56           ` Alexander Holler
2013-01-29  0:56             ` Alexander Holler
2013-01-29 10:35             ` Alexander Holler
2013-01-29 10:35               ` Alexander Holler
2013-01-29 11:11               ` Alexander Holler
2013-01-29 11:11                 ` Alexander Holler
2013-01-29 15:51                 ` Alexander Holler [this message]
2013-01-29 15:51                   ` Alexander Holler
2013-01-29 20:35                   ` Alexander Holler
2013-01-29 20:35                     ` Alexander Holler
2013-01-29 20:56                     ` Alexander Holler
2013-01-29 20:56                       ` Alexander Holler
2013-02-04  1:14                     ` Greg KH
2013-02-04  1:14                       ` Greg KH
2013-02-04 12:05                       ` Alexander Holler
2013-02-04 12:05                         ` Alexander Holler
2013-02-04 19:17                         ` Alexander Holler
2013-02-04 19:17                           ` Alexander Holler
2013-02-04 19:25                           ` Greg KH
2013-02-04 19:25                             ` Greg KH
2013-02-05  7:08                             ` Alexander Holler
2013-02-05  7:08                               ` Alexander Holler
2013-02-05 17:22                               ` Greg KH
2013-02-05 17:22                                 ` Greg KH
2013-02-05 17:36                                 ` Alexander Holler
2013-02-05 17:36                                   ` Alexander Holler
2013-02-08  4:07                                   ` Dave Airlie
2013-02-08  4:07                                     ` Dave Airlie
2013-02-08  9:53                                     ` Alexander Holler
2013-02-08  9:53                                       ` Alexander Holler
2013-01-25 18:49       ` [PATCH 3/3] fb: smscufx: " Alexander Holler
2013-01-25 18:49         ` Alexander Holler

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