On 01/08/2018 07:50 PM, Bart Van Assche wrote:
> Several SCSI transport and LLD drivers surround code that does not
> tolerate concurrent calls of .queuecommand() with scsi_target_block() /
> scsi_target_unblock(). These last two functions use
> blk_mq_quiesce_queue() / blk_mq_unquiesce_queue() for scsi-mq request
> queues to prevent concurrent .queuecommand() calls. However, that is
> not sufficient to prevent .queuecommand() calls from scsi_send_eh_cmnd().
> Hence surround the .queuecommand() call from the SCSI error handler with
> blk_wait_if_quiesced() / blk_finish_wait_if_quiesced().
>
> Note: converting the .queuecommand() call in scsi_send_eh_cmnd() into
> code that calls blk_get_request(), e.g. scsi_execute_req(), is not an
> option since scsi_send_eh_cmnd() can be called if all requests are
> allocated and if no requests will make progress without aborting any
> of these requests.
>
> Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx>
> Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Hannes Reinecke <hare@xxxxxxx>
> Cc: Johannes Thumshirn <jthumshirn@xxxxxxx>
> Cc: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
> drivers/scsi/scsi_error.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index 62b56de38ae8..5af3de1731a5 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -1016,6 +1016,7 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
> {
> struct scsi_device *sdev = scmd->device;
> struct Scsi_Host *shost = sdev->host;
> + struct request_queue *q = sdev->request_queue;
> DECLARE_COMPLETION_ONSTACK(done);
> unsigned long timeleft = timeout;
> struct scsi_eh_save ses;
> @@ -1028,7 +1029,9 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
>
> scsi_log_send(scmd);
> scmd->scsi_done = scsi_eh_done;
> + blk_wait_if_quiesced(q);
> rtn = shost->hostt->queuecommand(shost, scmd);
> + blk_finish_wait_if_quiesced(q);
> if (rtn) {
> if (timeleft > stall_for) {
> scsi_eh_restore_cmnd(scmd, &ses);
>
Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
