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/nsp32.c b/drivers/scsi/nsp32.c
index 4c1e54545200..6b8b021400f8 100644
--- a/drivers/scsi/nsp32.c
+++ b/drivers/scsi/nsp32.c
@@ -196,8 +196,7 @@ static void __exit    exit_nsp32  (void);
 static int         nsp32_proc_info   (struct Scsi_Host *, char *, char **, off_t, int, int);
 
 static int         nsp32_detect      (struct pci_dev *pdev);
-static int         nsp32_queuecommand(struct scsi_cmnd *,
-                void (*done)(struct scsi_cmnd *));
+static int         nsp32_queuecommand(struct Scsi_Host *, struct scsi_cmnd *);
 static const char *nsp32_info        (struct Scsi_Host *);
 static int         nsp32_release     (struct Scsi_Host *);
 
@@ -909,7 +908,7 @@ static int nsp32_setup_sg_table(struct scsi_cmnd *SCpnt)
         return TRUE;
 }
 
-static int nsp32_queuecommand(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *))
+static int nsp32_queuecommand_lck(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *))
 {
         nsp32_hw_data *data = (nsp32_hw_data *)SCpnt->device->host->hostdata;
         nsp32_target *target;
@@ -1050,6 +1049,8 @@ static int nsp32_queuecommand(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_
         return 0;
 }
 
+static DEF_SCSI_QCMD(nsp32_queuecommand)
+
 /* initialize asic */
 static int nsp32hw_init(nsp32_hw_data *data)
 {