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/aacraid/linit.c b/drivers/scsi/aacraid/linit.c
index 29c0ed1cf507..2c93d9496d62 100644
--- a/drivers/scsi/aacraid/linit.c
+++ b/drivers/scsi/aacraid/linit.c
@@ -248,7 +248,7 @@ static struct aac_driver_ident aac_drivers[] = {
  *      TODO: unify with aac_scsi_cmd().
  */
 
-static int aac_queuecommand(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *))
+static int aac_queuecommand_lck(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *))
 {
         struct Scsi_Host *host = cmd->device->host;
         struct aac_dev *dev = (struct aac_dev *)host->hostdata;
@@ -267,6 +267,8 @@ static int aac_queuecommand(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd
         return (aac_scsi_cmd(cmd) ? FAILED : 0);
 }
 
+static DEF_SCSI_QCMD(aac_queuecommand)
+
 /**
  *      aac_info                -       Returns the host adapter name
  *      @shost:         Scsi host to report on