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/drivers/scsi/wd33c93.h b/drivers/scsi/wd33c93.h
index 1ed5f3b..3b463d7 100644
--- a/drivers/scsi/wd33c93.h
+++ b/drivers/scsi/wd33c93.h
@@ -343,8 +343,7 @@ struct WD33C93_hostdata {
 void wd33c93_init (struct Scsi_Host *instance, const wd33c93_regs regs,
          dma_setup_t setup, dma_stop_t stop, int clock_freq);
 int wd33c93_abort (struct scsi_cmnd *cmd);
-int wd33c93_queuecommand (struct scsi_cmnd *cmd,
-		void (*done)(struct scsi_cmnd *));
+int wd33c93_queuecommand (struct Scsi_Host *h, struct scsi_cmnd *cmd);
 void wd33c93_intr (struct Scsi_Host *instance);
 int wd33c93_proc_info(struct Scsi_Host *, char *, char **, off_t, int, int);
 int wd33c93_host_reset (struct scsi_cmnd *);