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, 3 insertions, 1 deletions

diff --git a/drivers/scsi/in2000.c b/drivers/scsi/in2000.c
index 52bdc6df6b92..6568aab745a0 100644
--- a/drivers/scsi/in2000.c
+++ b/drivers/scsi/in2000.c
@@ -334,7 +334,7 @@ static uchar calc_sync_xfer(unsigned int period, unsigned int offset)
 
 static void in2000_execute(struct Scsi_Host *instance);
 
-static int in2000_queuecommand(Scsi_Cmnd * cmd, void (*done) (Scsi_Cmnd *))
+static int in2000_queuecommand_lck(Scsi_Cmnd * cmd, void (*done) (Scsi_Cmnd *))
 {
         struct Scsi_Host *instance;
         struct IN2000_hostdata *hostdata;
@@ -431,6 +431,8 @@ static int in2000_queuecommand(Scsi_Cmnd * cmd, void (*done) (Scsi_Cmnd *))
             return 0;
 }
 
+static DEF_SCSI_QCMD(in2000_queuecommand)
+
 
 
 /*