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/qlogicpti.c b/drivers/scsi/qlogicpti.c
index f8c561cf751e..664c9572d0c9 100644
--- a/drivers/scsi/qlogicpti.c
+++ b/drivers/scsi/qlogicpti.c
@@ -1003,7 +1003,7 @@ static int qlogicpti_slave_configure(struct scsi_device *sdev)
  *
  * "This code must fly." -davem
  */
-static int qlogicpti_queuecommand(struct scsi_cmnd *Cmnd, void (*done)(struct scsi_cmnd *))
+static int qlogicpti_queuecommand_lck(struct scsi_cmnd *Cmnd, void (*done)(struct scsi_cmnd *))
 {
         struct Scsi_Host *host = Cmnd->device->host;
         struct qlogicpti *qpti = (struct qlogicpti *) host->hostdata;
@@ -1052,6 +1052,8 @@ toss_command:
         return 1;
 }
 
+static DEF_SCSI_QCMD(qlogicpti_queuecommand)
+
 static int qlogicpti_return_status(struct Status_Entry *sts, int id)
 {
         int host_status = DID_ERROR;