On 06/06/12 13:29, Mike Christie wrote: > On 06/06/2012 07:17 AM, Bart Van Assche wrote: >> On 06/05/12 21:36, 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); >>>> + } >>> >>> If we do not requeue what eventually frees the request? >> >> As far as I can see any request passed to __scsi_queue_insert() has >> already been started. So if it isn't requeued it's timer remains active >> and hence will fire eventually. > > This is true in the scsi_dispatch_cmd path, but not others. > > If we were requeueing from the error handler scsi_eh_flush_done_q then > the timer would have been stopped because that is how we got into the eh. Given the above I propose to add a __blk_end_request_all(req, -ENXIO) call if the queue is dead. 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