tree fbb980129ed8b6ecabfed492f0c53b29280cd06e
parent 0b8393578c70bc1f09790eeae7d918f38da2e010
author James Bottomley <James.Bottomley@suse.de> 1303486799 -0500
committer James Bottomley <James.Bottomley@suse.de> 1303660937 -0500

[SCSI] put stricter guards on queue dead checks

SCSI uses request_queue->queuedata == NULL as a signal that the queue
is dying.  We set this state in the sdev release function.  However,
this allows a small window where we release the last reference but
haven't quite got to this stage yet and so something will try to take
a reference in scsi_request_fn and oops.  It's very rare, but we had a
report here, so we're pushing this as a bug fix

The actual fix is to set request_queue->queuedata to NULL in
scsi_remove_device() before we drop the reference.  This causes
correct automatic rejects from scsi_request_fn as people who hold
additional references try to submit work and prevents anything from
getting a new reference to the sdev that way.

Cc: stable@kernel.org
Signed-off-by: James Bottomley <James.Bottomley@suse.de>