linux-kernel - Re: [BUGFIX 2/2] gdth: bugfix for the Timer at exit crash

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Message-ID: <47B31FC2.4040206@panasas.com>
Date:	Wed, 13 Feb 2008 18:50:10 +0200
From:	Boaz Harrosh <bharrosh@...asas.com>
To:	James Bottomley <James.Bottomley@...senPartnership.com>
CC:	Sven Köhler <skoehler@....de>,
	Christoph Hellwig <hch@...radead.org>,
	Jeff Garzik <jeff@...zik.org>,
	linux-scsi <linux-scsi@...r.kernel.org>,
	linux-kernel@...r.kernel.org, Joerg Dorchain <joerg@...chain.net>,
	Jon Chelton <jchelton@...global.com>,
	Stefan Priebe - allied internet ag 
	<s.priebe@...ied-internet.ag>
Subject: Re: [BUGFIX 2/2] gdth: bugfix for the Timer at exit crash

On Wed, Feb 13 2008 at 18:45 +0200, James Bottomley <James.Bottomley@...senPartnership.com> wrote:
> On Wed, 2008-02-13 at 18:33 +0200, Boaz Harrosh wrote:
>> On Wed, Feb 13 2008 at 17:54 +0200, Boaz Harrosh <bharrosh@...asas.com> wrote:
>>> On Wed, Feb 13 2008 at 17:44 +0200, James Bottomley <James.Bottomley@...senPartnership.com> wrote:
>>>> On Tue, 2008-02-12 at 19:40 +0200, Boaz Harrosh wrote:
>>>>> -	gdth_flush(ha);
>>>>> -
>>>> This piece doesn't look right.  gdth_flush() forces the internal cache
>>>> to disk backing.  If you remove it, you're taking the chance that the
>>>> machine will be powered off without a writeback which can cause data
>>>> corruption.
>>>>
>>>> James
>>>>
>>> Yes. 
>>> I have more problems reported, with exit, and am just sending one more patch that puts
>>> this back in. Which was tested.
>>>
>>> So I will resend this one plus one new one.
>>>
>>> Boaz
>>>
>> The gdth driver would do a register_reboot_notifier(&gdth_notifier);
>> to a gdth_halt() function, which would then redo half of what gdth_exit
>> does, and wrongly so, and crash.  
>>
>> Are we guaranteed in todays kernel that modules .exit function be called
>> on an halt or reboot? If so then there is no need for duplications and
>> the gdth_halt() should go.
> 
> No.  The __exit section is actually discardable if you promise never to
> remove the module.
> 
I don't understand please explain. 
What does a driver need to do if it needs a consistent shutdown retine?
module or built in? unload or shutdown?


> James
> 
> 

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