SCSI host lock push-down

Move the mid-layer's ->queuecommand() invocation from being locked
with the host lock to being unlocked to facilitate speeding up the
critical path for drivers who don't need this lock taken anyway.

The patch below presents a simple SCSI host lock push-down as an
equivalent transformation.  No locking or other behavior should change
with this patch.  All existing bugs and locking orders are preserved.

Additionally, add one parameter to queuecommand,
	struct Scsi_Host *
and remove one parameter from queuecommand,
	void (*done)(struct scsi_cmnd *)

Scsi_Host* is a convenient pointer that most host drivers need anyway,
and 'done' is redundant to struct scsi_cmnd->scsi_done.

Minimal code disturbance was attempted with this change.  Most drivers
needed only two one-line modifications for their host lock push-down.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Acked-by: James Bottomley <James.Bottomley@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 2 deletions

diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index 3dec1949f69c..90ce527ecf3d 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -621,8 +621,7 @@ int sas_set_phy_speed(struct sas_phy *phy,
 int sas_phy_enable(struct sas_phy *phy, int enabled);
 int sas_phy_reset(struct sas_phy *phy, int hard_reset);
 int sas_queue_up(struct sas_task *task);
-extern int sas_queuecommand(struct scsi_cmnd *,
-                     void (*scsi_done)(struct scsi_cmnd *));
+extern int sas_queuecommand(struct Scsi_Host * ,struct scsi_cmnd *);
 extern int sas_target_alloc(struct scsi_target *);
 extern int sas_slave_alloc(struct scsi_device *);
 extern int sas_slave_configure(struct scsi_device *);