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>

4 files changed, 14 insertions, 7 deletions

diff --git a/drivers/message/fusion/mptfc.c b/drivers/message/fusion/mptfc.c
index e15220ff52fc..d784c36707c0 100644
--- a/drivers/message/fusion/mptfc.c
+++ b/drivers/message/fusion/mptfc.c
@@ -97,8 +97,7 @@ static u8	mptfcInternalCtx = MPT_MAX_PROTOCOL_DRIVERS;
 
 static int mptfc_target_alloc(struct scsi_target *starget);
 static int mptfc_slave_alloc(struct scsi_device *sdev);
-static int mptfc_qcmd(struct scsi_cmnd *SCpnt,
-		      void (*done)(struct scsi_cmnd *));
+static int mptfc_qcmd(struct Scsi_Host *shost, struct scsi_cmnd *SCpnt);
 static void mptfc_target_destroy(struct scsi_target *starget);
 static void mptfc_set_rport_loss_tmo(struct fc_rport *rport, uint32_t timeout);
 static void __devexit mptfc_remove(struct pci_dev *pdev);
@@ -650,7 +649,7 @@ mptfc_slave_alloc(struct scsi_device *sdev)
 }
 
 static int
-mptfc_qcmd(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *))
+mptfc_qcmd_lck(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *))
 {
 	struct mptfc_rport_info	*ri;
 	struct fc_rport	*rport = starget_to_rport(scsi_target(SCpnt->device));
@@ -681,6 +680,8 @@ mptfc_qcmd(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *))
 	return mptscsih_qcmd(SCpnt,done);
 }
 
+static DEF_SCSI_QCMD(mptfc_qcmd)
+
 /*
  *	mptfc_display_port_link_speed - displaying link speed
  *	@ioc: Pointer to MPT_ADAPTER structure
diff --git a/drivers/message/fusion/mptsas.c b/drivers/message/fusion/mptsas.c
index 83a5115f0251..d48c2c6058e1 100644
--- a/drivers/message/fusion/mptsas.c
+++ b/drivers/message/fusion/mptsas.c
@@ -1889,7 +1889,7 @@ mptsas_slave_alloc(struct scsi_device *sdev)
 }
 
 static int
-mptsas_qcmd(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *))
+mptsas_qcmd_lck(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *))
 {
 	MPT_SCSI_HOST	*hd;
 	MPT_ADAPTER	*ioc;
@@ -1913,6 +1913,8 @@ mptsas_qcmd(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *))
 	return mptscsih_qcmd(SCpnt,done);
 }
 
+static DEF_SCSI_QCMD(mptsas_qcmd)
+
 /**
  *	mptsas_mptsas_eh_timed_out - resets the scsi_cmnd timeout
  *		if the device under question is currently in the
diff --git a/drivers/message/fusion/mptspi.c b/drivers/message/fusion/mptspi.c
index 0e2803155ae2..6d9568d2ec59 100644
--- a/drivers/message/fusion/mptspi.c
+++ b/drivers/message/fusion/mptspi.c
@@ -780,7 +780,7 @@ static int mptspi_slave_configure(struct scsi_device *sdev)
 }
 
 static int
-mptspi_qcmd(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *))
+mptspi_qcmd_lck(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *))
 {
 	struct _MPT_SCSI_HOST *hd = shost_priv(SCpnt->device->host);
 	VirtDevice	*vdevice = SCpnt->device->hostdata;
@@ -805,6 +805,8 @@ mptspi_qcmd(struct scsi_cmnd *SCpnt, void (*done)(struct scsi_cmnd *))
 	return mptscsih_qcmd(SCpnt,done);
 }
 
+static DEF_SCSI_QCMD(mptspi_qcmd)
+
 static void mptspi_slave_destroy(struct scsi_device *sdev)
 {
 	struct scsi_target *starget = scsi_target(sdev);
diff --git a/drivers/message/i2o/i2o_scsi.c b/drivers/message/i2o/i2o_scsi.c
index ea6b2197da8a..97bdf82ec905 100644
--- a/drivers/message/i2o/i2o_scsi.c
+++ b/drivers/message/i2o/i2o_scsi.c
@@ -506,7 +506,7 @@ static struct i2o_driver i2o_scsi_driver = {
  *	Locks: takes the controller lock on error path only
  */
 
-static int i2o_scsi_queuecommand(struct scsi_cmnd *SCpnt,
+static int i2o_scsi_queuecommand_lck(struct scsi_cmnd *SCpnt,
 				 void (*done) (struct scsi_cmnd *))
 {
 	struct i2o_controller *c;
@@ -688,7 +688,9 @@ static int i2o_scsi_queuecommand(struct scsi_cmnd *SCpnt,
 
       exit:
 	return rc;
-};
+}
+
+static DEF_SCSI_QCMD(i2o_scsi_queuecommand)
 
 /**
  *	i2o_scsi_abort - abort a running command