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/ps3rom.c b/drivers/scsi/ps3rom.c
index 92ffbb510498..cd178b9e40cd 100644
--- a/drivers/scsi/ps3rom.c
+++ b/drivers/scsi/ps3rom.c
@@ -211,7 +211,7 @@ static int ps3rom_write_request(struct ps3_storage_device *dev,
         return 0;
 }
 
-static int ps3rom_queuecommand(struct scsi_cmnd *cmd,
+static int ps3rom_queuecommand_lck(struct scsi_cmnd *cmd,
                                void (*done)(struct scsi_cmnd *))
 {
         struct ps3rom_private *priv = shost_priv(cmd->device->host);
@@ -260,6 +260,8 @@ static int ps3rom_queuecommand(struct scsi_cmnd *cmd,
         return 0;
 }
 
+static DEF_SCSI_QCMD(ps3rom_queuecommand)
+
 static int decode_lv1_status(u64 status, unsigned char *sense_key,
                              unsigned char *asc, unsigned char *ascq)
 {