IB/srp: stop sharing the host lock with SCSI

We don't need protection against the SCSI stack, so use our own lock to
allow parallel progress on separate CPUs.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[ broken out and small cleanups by David Dillow ]
Signed-off-by: David Dillow <dillowda@ornl.gov>

2 files changed, 25 insertions, 23 deletions

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index e76fe54..8691fc8 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -447,12 +447,12 @@ static bool srp_change_state(struct srp_target_port *target,
 {
 	bool changed = false;
 
-	spin_lock_irq(target->scsi_host->host_lock);
+	spin_lock_irq(&target->lock);
 	if (target->state == old) {
 		target->state = new;
 		changed = true;
 	}
-	spin_unlock_irq(target->scsi_host->host_lock);
+	spin_unlock_irq(&target->lock);
 	return changed;
 }
 
@@ -555,11 +555,11 @@ static void srp_remove_req(struct srp_target_port *target,
 	unsigned long flags;
 
 	srp_unmap_data(req->scmnd, target, req);
-	spin_lock_irqsave(target->scsi_host->host_lock, flags);
+	spin_lock_irqsave(&target->lock, flags);
 	target->req_lim += req_lim_delta;
 	req->scmnd = NULL;
 	list_add_tail(&req->list, &target->free_reqs);
-	spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
+	spin_unlock_irqrestore(&target->lock, flags);
 }
 
 static void srp_reset_req(struct srp_target_port *target, struct srp_request *req)
@@ -634,13 +634,13 @@ err:
 	 * Schedule our work inside the lock to avoid a race with
 	 * the flush_scheduled_work() in srp_remove_one().
 	 */
-	spin_lock_irq(target->scsi_host->host_lock);
+	spin_lock_irq(&target->lock);
 	if (target->state == SRP_TARGET_CONNECTING) {
 		target->state = SRP_TARGET_DEAD;
 		INIT_WORK(&target->work, srp_remove_work);
 		schedule_work(&target->work);
 	}
-	spin_unlock_irq(target->scsi_host->host_lock);
+	spin_unlock_irq(&target->lock);
 
 	return ret;
 }
@@ -829,17 +829,16 @@ static void srp_put_tx_iu(struct srp_target_port *target, struct srp_iu *iu,
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(target->scsi_host->host_lock, flags);
+	spin_lock_irqsave(&target->lock, flags);
 	list_add(&iu->list, &target->free_tx);
 	if (iu_type != SRP_IU_RSP)
 		++target->req_lim;
-	spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
+	spin_unlock_irqrestore(&target->lock, flags);
 }
 
 /*
- * Must be called with target->scsi_host->host_lock held to protect
- * req_lim and free_tx.  If IU is not sent, it must be returned using
- * srp_put_tx_iu().
+ * Must be called with target->lock held to protect req_lim and free_tx.
+ * If IU is not sent, it must be returned using srp_put_tx_iu().
  *
  * Note:
  * An upper limit for the number of allocated information units for each
@@ -920,9 +919,9 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
 	unsigned long flags;
 
 	if (unlikely(rsp->tag & SRP_TAG_TSK_MGMT)) {
-		spin_lock_irqsave(target->scsi_host->host_lock, flags);
+		spin_lock_irqsave(&target->lock, flags);
 		target->req_lim += be32_to_cpu(rsp->req_lim_delta);
-		spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
+		spin_unlock_irqrestore(&target->lock, flags);
 
 		target->tsk_mgmt_status = -1;
 		if (be32_to_cpu(rsp->resp_data_len) >= 4)
@@ -963,10 +962,10 @@ static int srp_response_common(struct srp_target_port *target, s32 req_delta,
 	struct srp_iu *iu;
 	int err;
 
-	spin_lock_irqsave(target->scsi_host->host_lock, flags);
+	spin_lock_irqsave(&target->lock, flags);
 	target->req_lim += req_delta;
 	iu = __srp_get_tx_iu(target, SRP_IU_RSP);
-	spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
+	spin_unlock_irqrestore(&target->lock, flags);
 
 	if (!iu) {
 		shost_printk(KERN_ERR, target->scsi_host, PFX
@@ -1131,14 +1130,14 @@ static int srp_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *scmnd)
 		return 0;
 	}
 
-	spin_lock_irqsave(shost->host_lock, flags);
+	spin_lock_irqsave(&target->lock, flags);
 	iu = __srp_get_tx_iu(target, SRP_IU_CMD);
 	if (iu) {
 		req = list_first_entry(&target->free_reqs, struct srp_request,
 				      list);
 		list_del(&req->list);
 	}
-	spin_unlock_irqrestore(shost->host_lock, flags);
+	spin_unlock_irqrestore(&target->lock, flags);
 
 	if (!iu)
 		goto err;
@@ -1184,9 +1183,9 @@ err_unmap:
 err_iu:
 	srp_put_tx_iu(target, iu, SRP_IU_CMD);
 
-	spin_lock_irqsave(shost->host_lock, flags);
+	spin_lock_irqsave(&target->lock, flags);
 	list_add(&req->list, &target->free_reqs);
-	spin_unlock_irqrestore(shost->host_lock, flags);
+	spin_unlock_irqrestore(&target->lock, flags);
 
 err:
 	return SCSI_MLQUEUE_HOST_BUSY;
@@ -1451,9 +1450,9 @@ static int srp_send_tsk_mgmt(struct srp_target_port *target,
 
 	init_completion(&target->tsk_mgmt_done);
 
-	spin_lock_irq(target->scsi_host->host_lock);
+	spin_lock_irq(&target->lock);
 	iu = __srp_get_tx_iu(target, SRP_IU_TSK_MGMT);
-	spin_unlock_irq(target->scsi_host->host_lock);
+	spin_unlock_irq(&target->lock);
 
 	if (!iu)
 		return -1;
@@ -1957,6 +1956,7 @@ static ssize_t srp_create_target(struct device *dev,
 	target->scsi_host  = target_host;
 	target->srp_host   = host;
 
+	spin_lock_init(&target->lock);
 	INIT_LIST_HEAD(&target->free_tx);
 	INIT_LIST_HEAD(&target->free_reqs);
 	for (i = 0; i < SRP_CMD_SQ_SIZE; ++i) {
@@ -2186,9 +2186,9 @@ static void srp_remove_one(struct ib_device *device)
 		 */
 		spin_lock(&host->target_lock);
 		list_for_each_entry(target, &host->target_list, list) {
-			spin_lock_irq(target->scsi_host->host_lock);
+			spin_lock_irq(&target->lock);
 			target->state = SRP_TARGET_REMOVED;
-			spin_unlock_irq(target->scsi_host->host_lock);
+			spin_unlock_irq(&target->lock);
 		}
 		spin_unlock(&host->target_lock);
 
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index 81686ee..acb435d 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -144,6 +144,8 @@ struct srp_target_port {
 
 	struct srp_iu	       *rx_ring[SRP_RQ_SIZE];
 
+	spinlock_t		lock;
+
 	struct list_head	free_tx;
 	struct srp_iu	       *tx_ring[SRP_SQ_SIZE];