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, 8 insertions, 10 deletions

diff --git a/drivers/scsi/arm/fas216.h b/drivers/scsi/arm/fas216.h
index b65f4cf0eec9..377cfb72cc66 100644
--- a/drivers/scsi/arm/fas216.h
+++ b/drivers/scsi/arm/fas216.h
@@ -331,23 +331,21 @@ extern int fas216_init (struct Scsi_Host *instance);
  */
 extern int fas216_add (struct Scsi_Host *instance, struct device *dev);
 
-/* Function: int fas216_queue_command(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *))
+/* Function: int fas216_queue_command(struct Scsi_Host *h, struct scsi_cmnd *SCpnt)
  * Purpose : queue a command for adapter to process.
- * Params  : SCpnt - Command to queue
- *           done  - done function to call once command is complete
+ * Params  : h - host adapter
+ *         : SCpnt - Command to queue
  * Returns : 0 - success, else error
  */
-extern int fas216_queue_command(struct scsi_cmnd *,
-                                void (*done)(struct scsi_cmnd *));
+extern int fas216_queue_command(struct Scsi_Host *h, struct scsi_cmnd *SCpnt);
 
-/* Function: int fas216_noqueue_command(istruct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *))
+/* Function: int fas216_noqueue_command(struct Scsi_Host *h, struct scsi_cmnd *SCpnt)
  * Purpose : queue a command for adapter to process, and process it to completion.
- * Params  : SCpnt - Command to queue
- *           done  - done function to call once command is complete
+ * Params  : h - host adapter
+ *         : SCpnt - Command to queue
  * Returns : 0 - success, else error
  */
-extern int fas216_noqueue_command(struct scsi_cmnd *,
-                                  void (*done)(struct scsi_cmnd *));
+extern int fas216_noqueue_command(struct Scsi_Host *, struct scsi_cmnd *)
 
 /* Function: irqreturn_t fas216_intr (FAS216_Info *info)
  * Purpose : handle interrupts from the interface to progress a command