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>

2 files changed, 4 insertions, 2 deletions

diff --git a/drivers/scsi/fnic/fnic.h b/drivers/scsi/fnic/fnic.h
index cbb20b13b228..92f185081e62 100644
--- a/drivers/scsi/fnic/fnic.h
+++ b/drivers/scsi/fnic/fnic.h
@@ -246,7 +246,7 @@ void fnic_set_port_id(struct fc_lport *, u32, struct fc_frame *);
 void fnic_update_mac(struct fc_lport *, u8 *new);
 void fnic_update_mac_locked(struct fnic *, u8 *new);
 
-int fnic_queuecommand(struct scsi_cmnd *, void (*done)(struct scsi_cmnd *));
+int fnic_queuecommand(struct Scsi_Host *, struct scsi_cmnd *);
 int fnic_abort_cmd(struct scsi_cmnd *);
 int fnic_device_reset(struct scsi_cmnd *);
 int fnic_host_reset(struct scsi_cmnd *);
diff --git a/drivers/scsi/fnic/fnic_scsi.c b/drivers/scsi/fnic/fnic_scsi.c
index 198cbab3e894..22d02404d15f 100644
--- a/drivers/scsi/fnic/fnic_scsi.c
+++ b/drivers/scsi/fnic/fnic_scsi.c
@@ -349,7 +349,7 @@ static inline int fnic_queue_wq_copy_desc(struct fnic *fnic,
  * Routine to send a scsi cdb
  * Called with host_lock held and interrupts disabled.
  */
-int fnic_queuecommand(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
+static int fnic_queuecommand_lck(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
 {
         struct fc_lport *lp;
         struct fc_rport *rport;
@@ -457,6 +457,8 @@ out:
         return ret;
 }
 
+DEF_SCSI_QCMD(fnic_queuecommand)
+
 /*
  * fnic_fcpio_fw_reset_cmpl_handler
  * Routine to handle fw reset completion