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, 2 deletions

diff --git a/drivers/scsi/u14-34f.c b/drivers/scsi/u14-34f.c
index 5d9fdeeb2315..edfc5da8be4c 100644
--- a/drivers/scsi/u14-34f.c
+++ b/drivers/scsi/u14-34f.c
@@ -433,7 +433,7 @@
 
 static int u14_34f_detect(struct scsi_host_template *);
 static int u14_34f_release(struct Scsi_Host *);
-static int u14_34f_queuecommand(struct scsi_cmnd *, void (*done)(struct scsi_cmnd *));
+static int u14_34f_queuecommand(struct Scsi_Host *, struct scsi_cmnd *);
 static int u14_34f_eh_abort(struct scsi_cmnd *);
 static int u14_34f_eh_host_reset(struct scsi_cmnd *);
 static int u14_34f_bios_param(struct scsi_device *, struct block_device *,
@@ -1248,7 +1248,7 @@ static void scsi_to_dev_dir(unsigned int i, unsigned int j) {
 
 }
 
-static int u14_34f_queuecommand(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *)) {
+static int u14_34f_queuecommand_lck(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *)) {
    unsigned int i, j, k;
    struct mscp *cpp;
 
@@ -1329,6 +1329,8 @@ static int u14_34f_queuecommand(struct scsi_cmnd *SCpnt, void (*done)(struct scs
    return 0;
 }
 
+static DEF_SCSI_QCMD(u14_34f_queuecommand)
+
 static int u14_34f_eh_abort(struct scsi_cmnd *SCarg) {
    unsigned int i, j;