On 08/04/2018 02:03 AM, Bart Van Assche wrote:

In kernel v2.6.18 RQF_PREEMPT was only set for IDE preempt requests.
Later on the SCSI core was modified such that RQF_PREEMPT requests
was set for all requests submitted by __scsi_execute(), including
power management requests. RQF_PREEMPT requests are the only requests
processed in the SDEV_QUIESCE state. Instead of setting RQF_PREEMPT
for all requests submitted by __scsi_execute(), only set RQF_PM for
power management requests. Modify blk_get_request() such that it
blocks in pm-only mode on non-RQF_PM requests. Leave the code out
from scsi_prep_state_check() that is no longer reachable.

Signed-off-by: Bart Van Assche <redacted>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jianchao Wang <redacted>
Cc: Ming Lei <redacted>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Johannes Thumshirn <redacted>
---
 block/blk-core.c        |  9 +++++----
 drivers/scsi/scsi_lib.c | 28 ++++++++++++----------------
 include/linux/blk-mq.h  |  2 ++
 include/linux/blkdev.h  |  6 ++----
 4 files changed, 21 insertions(+), 24 deletions(-)

I am not sure this is going to work for SCSI parallel; we're using the
QUIESCE state there to do domain validation, and all commands there are
most definitely not PM requests.
Can you please validate your patches with eg aic7xxx and SCSI parallel
disks?

Thanks.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
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