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>

115 files changed, 347 insertions, 199 deletions

diff --git a/arch/ia64/hp/sim/simscsi.c b/arch/ia64/hp/sim/simscsi.c
index 3a078ad3aa44..331de723c676 100644
--- a/arch/ia64/hp/sim/simscsi.c
+++ b/arch/ia64/hp/sim/simscsi.c
@@ -202,7 +202,7 @@ simscsi_readwrite10 (struct scsi_cmnd *sc, int mode)
 }
 
 static int
-simscsi_queuecommand (struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
+simscsi_queuecommand_lck (struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
 {
 	unsigned int target_id = sc->device->id;
 	char fname[MAX_ROOT_LEN+16];
@@ -326,6 +326,8 @@ simscsi_queuecommand (struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
 	return 0;
 }
 
+static DEF_SCSI_QCMD(simscsi_queuecommand)
+
 static int
 simscsi_host_reset (struct scsi_cmnd *sc)
 {
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 3f91c01c217f..19835d39289d 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3183,7 +3183,7 @@ static inline int __ata_scsi_queuecmd(struct scsi_cmnd *scmd,
  *	Return value from __ata_scsi_queuecmd() if @cmd can be queued,
  *	0 otherwise.
  */
-int ata_scsi_queuecmd(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *))
+static int ata_scsi_queuecmd_lck(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *))
 {
 	struct ata_port *ap;
 	struct ata_device *dev;
@@ -3211,6 +3211,8 @@ int ata_scsi_queuecmd(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *))
 	return rc;
 }
 
+DEF_SCSI_QCMD(ata_scsi_queuecmd)
+
 /**
  *	ata_scsi_simulate - simulate SCSI command on ATA device
  *	@dev: the target device
diff --git a/drivers/block/cciss_scsi.c b/drivers/block/cciss_scsi.c
index 575495f3c4b8..727d0225b7d0 100644
--- a/drivers/block/cciss_scsi.c
+++ b/drivers/block/cciss_scsi.c
@@ -62,8 +62,8 @@ static int cciss_scsi_proc_info(
 		int length, 	   /* length of data in buffer */
 		int func);	   /* 0 == read, 1 == write */
 
-static int cciss_scsi_queue_command (struct scsi_cmnd *cmd,
-		void (* done)(struct scsi_cmnd *));
+static int cciss_scsi_queue_command (struct Scsi_Host *h,
+				     struct scsi_cmnd *cmd);
 static int cciss_eh_device_reset_handler(struct scsi_cmnd *);
 static int cciss_eh_abort_handler(struct scsi_cmnd *);
 
@@ -1406,7 +1406,7 @@ static void cciss_scatter_gather(ctlr_info_t *h, CommandList_struct *c,
 
 
 static int
-cciss_scsi_queue_command (struct scsi_cmnd *cmd, void (* done)(struct scsi_cmnd *))
+cciss_scsi_queue_command_lck(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *))
 {
 	ctlr_info_t *h;
 	int rc;
@@ -1504,6 +1504,8 @@ cciss_scsi_queue_command (struct scsi_cmnd *cmd, void (* done)(struct scsi_cmnd
 	return 0;
 }
 
+static DEF_SCSI_QCMD(cciss_scsi_queue_command)
+
 static void cciss_unregister_scsi(ctlr_info_t *h)
 {
 	struct cciss_scsi_adapter_data_t *sa;
diff --git a/drivers/firewire/sbp2.c b/drivers/firewire/sbp2.c
index bfae4b309791..afa576a75a8e 100644
--- a/drivers/firewire/sbp2.c
+++ b/drivers/firewire/sbp2.c
@@ -1468,7 +1468,7 @@ static int sbp2_map_scatterlist(struct sbp2_command_orb *orb,
 
 /* SCSI stack integration */
 
-static int sbp2_scsi_queuecommand(struct scsi_cmnd *cmd, scsi_done_fn_t done)
+static int sbp2_scsi_queuecommand_lck(struct scsi_cmnd *cmd, scsi_done_fn_t done)
 {
 	struct sbp2_logical_unit *lu = cmd->device->hostdata;
 	struct fw_device *device = target_device(lu->tgt);
@@ -1534,6 +1534,8 @@ static int sbp2_scsi_queuecommand(struct scsi_cmnd *cmd, scsi_done_fn_t done)
 	return retval;
 }
 
+static DEF_SCSI_QCMD(sbp2_scsi_queuecommand)
+
 static int sbp2_scsi_slave_alloc(struct scsi_device *sdev)
 {
 	struct sbp2_logical_unit *lu = sdev->hostdata;
diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index cfc1d65c4577..1e1e347a7715 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -1123,7 +1123,7 @@ static void srp_send_completion(struct ib_cq *cq, void *target_ptr)
 	}
 }
 
-static int srp_queuecommand(struct scsi_cmnd *scmnd,
+static int srp_queuecommand_lck(struct scsi_cmnd *scmnd,
 			    void (*done)(struct scsi_cmnd *))
 {
 	struct srp_target_port *target = host_to_target(scmnd->device->host);
@@ -1196,6 +1196,8 @@ err:
 	return SCSI_MLQUEUE_HOST_BUSY;
 }
 
+static DEF_SCSI_QCMD(srp_queuecommand)
+
 static int srp_alloc_iu_bufs(struct srp_target_port *target)
 {
 	int i;
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 *))
 {