From mboxrd@z Thu Jan  1 00:00:00 1970
From: James Bottomley <James.Bottomley@HansenPartnership.com>
Subject: Re: [PATCH] SCSI IOCTL: Check for device deletion [was Re:
 __elv_add_request OOPS]
Date: Wed, 25 May 2011 15:20:18 -0500
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To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Parag Warudkar <parag.lkml@gmail.com>, Jens Axboe <jaxboe@fusionio.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "akpm@linux-foundation.org" <akpm@linux-foundation.org>, Linux SCSI List <linux-scsi@vger.kernel.org>
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On Wed, 2011-05-25 at 13:03 -0700, Linus Torvalds wrote:
> On Wed, May 25, 2011 at 12:52 PM, Parag Warudkar <parag.lkml@gmail.com> wrote:
> >
> > +static inline int sdev_early_check(struct scsi_device *sdev)
> > +{
> > +       if (!sdev || sdev->sdev_state == SDEV_DEL
> > +               || sdev->sdev_state > SDEV_QUIESCE)
> > +               return -ENXIO;
> > +       return 0;
> > +}
> 
> Can somebody explain why it's those states, and nothing else?

The states are definitely wrong.  QUIESCE shouldn't cause an error.

Can we back up a bit.  I agree with Jens that sdev->request_queue looks
to be NULL, but that *only* happens in the final sdev release, so this
must be a refcounting problem higher up the stack.  Something is holding
an unrefcounted pointer to the sdev.

James