scsi: hisi_sas: optimise the usage of hisi_hba.lock

Currently hisi_hba.lock is locked to deliver and receive a command
to/from any hw queue. This causes much contention at high data-rates.

To boost performance, lock on a per queue basis for sending and
receiving commands to/from hw.

Certain critical regions still need to be locked in the delivery and
completion stages with hisi_hba.lock.

New element hisi_sas_device.dq is added to store the delivery queue for
a device, so it does not need to be needlessly re-calculated for every
task.

Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 17 insertions, 17 deletions

diff --git a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
index e241921bee10..2607aac00ac9 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
@@ -695,6 +695,9 @@ hisi_sas_device *alloc_dev_quirk_v2_hw(struct domain_device *device)
 		if (sata_dev && (i & 1))
 			continue;
 		if (hisi_hba->devices[i].dev_type == SAS_PHY_UNUSED) {
+			int queue = i % hisi_hba->queue_count;
+			struct hisi_sas_dq *dq = &hisi_hba->dq[queue];
+
 			hisi_hba->devices[i].device_id = i;
 			sas_dev = &hisi_hba->devices[i];
 			sas_dev->dev_status = HISI_SAS_DEV_NORMAL;
@@ -702,6 +705,7 @@ hisi_sas_device *alloc_dev_quirk_v2_hw(struct domain_device *device)
 			sas_dev->hisi_hba = hisi_hba;
 			sas_dev->sas_device = device;
 			sas_dev->sata_idx = sata_idx;
+			sas_dev->dq = dq;
 			INIT_LIST_HEAD(&hisi_hba->devices[i].list);
 			break;
 		}
@@ -1454,22 +1458,17 @@ static int get_wideport_bitmap_v2_hw(struct hisi_hba *hisi_hba, int port_id)
 	return bitmap;
 }
 
-/**
- * This function allocates across all queues to load balance.
- * Slots are allocated from queues in a round-robin fashion.
- *
+/*
  * The callpath to this function and upto writing the write
  * queue pointer should be safe from interruption.
  */
-static int get_free_slot_v2_hw(struct hisi_hba *hisi_hba, u32 dev_id,
-				int *q, int *s)
+static int
+get_free_slot_v2_hw(struct hisi_hba *hisi_hba, struct hisi_sas_dq *dq)
 {
 	struct device *dev = &hisi_hba->pdev->dev;
-	struct hisi_sas_dq *dq;
+	int queue = dq->id;
 	u32 r, w;
-	int queue = dev_id % hisi_hba->queue_count;
 
-	dq = &hisi_hba->dq[queue];
 	w = dq->wr_point;
 	r = hisi_sas_read32_relaxed(hisi_hba,
 				DLVRY_Q_0_RD_PTR + (queue * 0x14));
@@ -1479,16 +1478,14 @@ static int get_free_slot_v2_hw(struct hisi_hba *hisi_hba, u32 dev_id,
 		return -EAGAIN;
 	}
 
-	*q = queue;
-	*s = w;
 	return 0;
 }
 
-static void start_delivery_v2_hw(struct hisi_hba *hisi_hba)
+static void start_delivery_v2_hw(struct hisi_sas_dq *dq)
 {
-	int dlvry_queue = hisi_hba->slot_prep->dlvry_queue;
-	int dlvry_queue_slot = hisi_hba->slot_prep->dlvry_queue_slot;
-	struct hisi_sas_dq *dq = &hisi_hba->dq[dlvry_queue];
+	struct hisi_hba *hisi_hba = dq->hisi_hba;
+	int dlvry_queue = dq->slot_prep->dlvry_queue;
+	int dlvry_queue_slot = dq->slot_prep->dlvry_queue_slot;
 
 	dq->wr_point = ++dlvry_queue_slot % HISI_SAS_QUEUE_SLOTS;
 	hisi_sas_write32(hisi_hba, DLVRY_Q_0_WR_PTR + (dlvry_queue * 0x14),
@@ -2344,7 +2341,9 @@ out:
 	spin_lock_irqsave(&task->task_state_lock, flags);
 	task->task_state_flags |= SAS_TASK_STATE_DONE;
 	spin_unlock_irqrestore(&task->task_state_lock, flags);
+	spin_lock_irqsave(&hisi_hba->lock, flags);
 	hisi_sas_slot_task_free(hisi_hba, task, slot);
+	spin_unlock_irqrestore(&hisi_hba->lock, flags);
 	sts = ts->stat;
 
 	if (task->task_done)
@@ -3162,13 +3161,14 @@ static void cq_tasklet_v2_hw(unsigned long val)
 	struct hisi_sas_complete_v2_hdr *complete_queue;
 	u32 rd_point = cq->rd_point, wr_point, dev_id;
 	int queue = cq->id;
+	struct hisi_sas_dq *dq = &hisi_hba->dq[queue];
 
 	if (unlikely(hisi_hba->reject_stp_links_msk))
 		phys_try_accept_stp_links_v2_hw(hisi_hba);
 
 	complete_queue = hisi_hba->complete_hdr[queue];
 
-	spin_lock(&hisi_hba->lock);
+	spin_lock(&dq->lock);
 	wr_point = hisi_sas_read32(hisi_hba, COMPL_Q_0_WR_PTR +
 				   (0x14 * queue));
 
@@ -3218,7 +3218,7 @@ static void cq_tasklet_v2_hw(unsigned long val)
 	/* update rd_point */
 	cq->rd_point = rd_point;
 	hisi_sas_write32(hisi_hba, COMPL_Q_0_RD_PTR + (0x14 * queue), rd_point);
-	spin_unlock(&hisi_hba->lock);
+	spin_unlock(&dq->lock);
 }
 
 static irqreturn_t cq_interrupt_v2_hw(int irq_no, void *p)