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/tmscsim.c b/drivers/scsi/tmscsim.c
index 27866b0adfeb..a124a28f2ccb 100644
--- a/drivers/scsi/tmscsim.c
+++ b/drivers/scsi/tmscsim.c
@@ -1883,7 +1883,7 @@ dc390_ScsiRstDetect( struct dc390_acb* pACB )
     return;
 }
 
-static int DC390_queuecommand(struct scsi_cmnd *cmd,
+static int DC390_queuecommand_lck(struct scsi_cmnd *cmd,
                 void (*done)(struct scsi_cmnd *))
 {
         struct scsi_device *sdev = cmd->device;
@@ -1944,6 +1944,8 @@ static int DC390_queuecommand(struct scsi_cmnd *cmd,
         return SCSI_MLQUEUE_DEVICE_BUSY;
 }
 
+static DEF_SCSI_QCMD(DC390_queuecommand)
+
 static void dc390_dumpinfo (struct dc390_acb* pACB, struct dc390_dcb* pDCB, struct dc390_srb* pSRB)
 {
     struct pci_dev *pdev;