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, 4 insertions, 3 deletions

diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index c5d0606ad097..3759d1199b0c 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -143,8 +143,7 @@ static void fill_cmd(struct CommandList *c, u8 cmd, struct ctlr_info *h,
         void *buff, size_t size, u8 page_code, unsigned char *scsi3addr,
         int cmd_type);
 
-static int hpsa_scsi_queue_command(struct scsi_cmnd *cmd,
-                void (*done)(struct scsi_cmnd *));
+static int hpsa_scsi_queue_command(struct Scsi_Host *h, struct scsi_cmnd *cmd);
 static void hpsa_scan_start(struct Scsi_Host *);
 static int hpsa_scan_finished(struct Scsi_Host *sh,
         unsigned long elapsed_time);
@@ -1926,7 +1925,7 @@ sglist_finished:
 }
 
 
-static int hpsa_scsi_queue_command(struct scsi_cmnd *cmd,
+static int hpsa_scsi_queue_command_lck(struct scsi_cmnd *cmd,
         void (*done)(struct scsi_cmnd *))
 {
         struct ctlr_info *h;
@@ -2020,6 +2019,8 @@ static int hpsa_scsi_queue_command(struct scsi_cmnd *cmd,
         return 0;
 }
 
+static DEF_SCSI_QCMD(hpsa_scsi_queue_command)
+
 static void hpsa_scan_start(struct Scsi_Host *sh)
 {
         struct ctlr_info *h = shost_to_hba(sh);