[PATCH v4 0/5] ufs: Do not requeue while ungating the clock

From: Bart Van Assche <bvanassche@acm.org>
To: "Martin K . Petersen" <martin.petersen@oracle.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>,
	linux-scsi@vger.kernel.org,
	Adrian Hunter <adrian.hunter@intel.com>,
	Bart Van Assche <bvanassche@acm.org>
Subject: [PATCH v4 0/5] ufs: Do not requeue while ungating the clock
Date: Mon, 29 May 2023 13:26:35 -0700	[thread overview]
Message-ID: <20230529202640.11883-1-bvanassche@acm.org> (raw)

Hi Martin,

In the traces we recorded while testing zoned storage we noticed that UFS
commands are requeued while the clock is being ungated. Command requeueing
makes it harder than necessary to preserve the command order. Hence this
patch series that modifies the SCSI core and also the UFS driver such that
clock ungating does not trigger command requeueing.

Please consider this patch series for the next merge window.

Thanks,

Bart.

Changes compared to v3:
- Added a patch that removes two duplicate declarations.

Changes compared to v2:
- Only enable BLK_MQ_F_BLOCKING if clock gating is supported.
- Introduce flag queuecommand_may_block in both the SCSI host and SCSI host
  template data structures.

Changes compared to v1:
- Dropped patch "scsi: ufs: core: Unexport ufshcd_hold() and ufshcd_release()".
- Removed a ufshcd_scsi_block_requests() / ufshcd_scsi_unblock_requests() pair
  from patch "scsi: ufs: Ungate the clock synchronously".

Bart Van Assche (4):
  scsi: core: Rework scsi_host_block()
  scsi: core: Support setting BLK_MQ_F_BLOCKING
  scsi: ufs: Conditionally enable the BLK_MQ_F_BLOCKING flag
  scsi: ufs: Ungate the clock synchronously

Bart Van Assche (5):
  scsi: core: Rework scsi_host_block()
  scsi: core: Support setting BLK_MQ_F_BLOCKING
  scsi: ufs: Conditionally enable the BLK_MQ_F_BLOCKING flag
  scsi: ufs: Declare ufshcd_{hold,release}() once
  scsi: ufs: Ungate the clock synchronously

 drivers/scsi/hosts.c             |  1 +
 drivers/scsi/scsi_lib.c          | 27 ++++++----
 drivers/ufs/core/ufs-sysfs.c     |  2 +-
 drivers/ufs/core/ufshcd-crypto.c |  2 +-
 drivers/ufs/core/ufshcd-priv.h   |  3 --
 drivers/ufs/core/ufshcd.c        | 87 ++++++++++----------------------
 include/scsi/scsi_host.h         |  6 +++
 include/ufs/ufshcd.h             |  2 +-
 8 files changed, 54 insertions(+), 76 deletions(-)