linux-kernel - Re: [PATCH] SCSI IOCTL: Check for device deletion [was Re: __elv_add

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Date:	Sat, 28 May 2011 14:42:21 +0200
From:	Jens Axboe <jaxboe@...ionio.com>
To:	James Bottomley <James.Bottomley@...senPartnership.com>
CC:	Parag Warudkar <parag.lkml@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	Linux SCSI List <linux-scsi@...r.kernel.org>
Subject: Re: [PATCH] SCSI IOCTL: Check for device deletion [was Re:   __elv_add_request
 OOPS]

On 2011-05-27 22:21, James Bottomley wrote:
> On Fri, 2011-05-27 at 07:43 +0200, Jens Axboe wrote: 
>> On 2011-05-27 05:53, James Bottomley wrote:
>>> On Wed, 2011-05-25 at 15:52 -0500, James Bottomley wrote:
>>>> On Wed, 2011-05-25 at 16:42 -0400, Parag Warudkar wrote:
>>>>> Yeah - that makes sense. By that logic, looks like we can only disallow 
>>>>> for SDEV_DEL (if we decide to do that check here).
>>>>
>>>> I don't think this is the root cause.  I think q is non-NULL but has
>>>> already been released, so we're just getting a NULL deref on the actual
>>>> list head.
>>>>
>>>> Does this fix it?  It adds the refcounting at approximately the correct
>>>> places.  Of course, we'll now be trying elevator operations on an extant
>>>> queue but one whose elevator functions have been destroyed, so there are
>>>> probably additional state guards to place.
>>>>
>>>> James
>>>>
>>>> ---
>>>>
>>>> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
>>>> index 58584dc..44e8ca3 100644
>>>> --- a/drivers/scsi/scsi_scan.c
>>>> +++ b/drivers/scsi/scsi_scan.c
>>>> @@ -297,7 +297,7 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget,
>>>>  		kfree(sdev);
>>>>  		goto out;
>>>>  	}
>>>> -
>>>> +	blk_get_queue(sdev->request_queue);
>>>
>>> Apparently we can't do this because blk_[put|get]_queue aren't exported
>>> for use in modules (and SCSI can be modular), so this caused a build
>>> failure in linux-next.
>>
>> I'll just export them.
> 
> OK, if you're fine with that, how does this patch look?

Outdated :-)

I already merged the export addition:

commit d86e0e83b32bc84600adb0b6ea1fce389b266682
Author: Jens Axboe <jaxboe@...ionio.com>
Date:   Fri May 27 07:44:43 2011 +0200

    block: export blk_{get,put}_queue()

> I can take it through my rc-fixes tree (with your ack), since I'm a bit
> late on the merge window now.

Only the SCSI bit remains, so add at will. You can add my acked-by to
that standalone, if you wish.

-- 
Jens Axboe

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