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/eata.c b/drivers/scsi/eata.c
index d1c31378f6da..53925ac178fd 100644
--- a/drivers/scsi/eata.c
+++ b/drivers/scsi/eata.c
@@ -505,8 +505,7 @@
 
 static int eata2x_detect(struct scsi_host_template *);
 static int eata2x_release(struct Scsi_Host *);
-static int eata2x_queuecommand(struct scsi_cmnd *,
-                               void (*done) (struct scsi_cmnd *));
+static int eata2x_queuecommand(struct Scsi_Host *, struct scsi_cmnd *);
 static int eata2x_eh_abort(struct scsi_cmnd *);
 static int eata2x_eh_host_reset(struct scsi_cmnd *);
 static int eata2x_bios_param(struct scsi_device *, struct block_device *,
@@ -1758,7 +1757,7 @@ static void scsi_to_dev_dir(unsigned int i, struct hostdata *ha)
 
 }
 
-static int eata2x_queuecommand(struct scsi_cmnd *SCpnt,
+static int eata2x_queuecommand_lck(struct scsi_cmnd *SCpnt,
                                void (*done) (struct scsi_cmnd *))
 {
         struct Scsi_Host *shost = SCpnt->device->host;
@@ -1843,6 +1842,8 @@ static int eata2x_queuecommand(struct scsi_cmnd *SCpnt,
         return 0;
 }
 
+static DEF_SCSI_QCMD(eata2x_queuecommand)
+
 static int eata2x_eh_abort(struct scsi_cmnd *SCarg)
 {
         struct Scsi_Host *shost = SCarg->device->host;