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.
Bart.
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