On 06/05/12 22:08, Mike Christie wrote:
> On 06/05/2012 12:14 PM, Bart Van Assche wrote:
>> Avoid that the code for requeueing SCSI requests triggers a
>> crash by making sure that that code isn't scheduled anymore
>> after a device has been removed.
>>
>> Also, source code inspection of __scsi_remove_device() revealed
>> a race condition in this function: no new SCSI requests must be
>> accepted for a SCSI device after device removal started.
>>
>> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
>> Cc: Mike Christie <michaelc@xxxxxxxxxxx>
>> Cc: James Bottomley <JBottomley@xxxxxxxxxxxxx>
>> Cc: Jens Axboe <axboe@xxxxxxxxx>
>> Cc: Joe Lawrence <jdl1291@xxxxxxxxx>
>> Cc: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>
>> Cc: <stable@xxxxxxxxxx>
>> ---
>> drivers/scsi/scsi_lib.c | 7 ++++---
>> drivers/scsi/scsi_sysfs.c | 11 +++++++++--
>> 2 files changed, 13 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
>> index 082c1e5..b722a8b 100644
>> --- a/drivers/scsi/scsi_lib.c
>> +++ b/drivers/scsi/scsi_lib.c
>> @@ -158,10 +158,11 @@ static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
>> * that are already in the queue.
>> */
>> spin_lock_irqsave(q->queue_lock, flags);
>> - blk_requeue_request(q, cmd->request);
>> + if (!blk_queue_dead(q)) {
>> + blk_requeue_request(q, cmd->request);
>> + kblockd_schedule_work(q, &device->requeue_work);
>> + }
>> spin_unlock_irqrestore(q->queue_lock, flags);
>> -
>> - kblockd_schedule_work(q, &device->requeue_work);
>
> If we do not have the part of the patch above, but have your other
> patches and the code below, will we be ok?
I'm not sure. Without the above part the request could get killed after
the blk_requeue_request() call finished but before the requeue_work is
scheduled, e.g. because the request timer fired or due to a
blk_abort_queue() call.
Bart.
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
