scsi: qla2xxx: Move heartbeat handling from DPC thread to workqueue

DPC thread gets restricted due to a no-op mailbox, which is a blocking call
and has a high execution frequency. To free up the DPC thread we move no-op
handling to the workqueue. Also, modified qla_do_heartbeat() to send no-op
MBC if we don’t have any active interrupts, but there are still I/Os
outstanding with firmware.

Link: https://lore.kernel.org/r/20210908164622.19240-9-njavali@marvell.com
Fixes: d94d8158 ("scsi: qla2xxx: Add heartbeat check")
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Manish Rangankar <mrangankar@marvell.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_def.h

@@ -3750,6 +3750,7 @@ struct qla_qpair {
 	struct qla_fw_resources fwres ____cacheline_aligned;
 	u32	cmd_cnt;
 	u32	cmd_completion_cnt;
+	u32	prev_completion_cnt;
 };
 
 /* Place holder for FW buffer parameters */
@@ -4607,6 +4608,7 @@ struct qla_hw_data {
 	struct qla_chip_state_84xx *cs84xx;
 	struct isp_operations *isp_ops;
 	struct workqueue_struct *wq;
+	struct work_struct heartbeat_work;
 	struct qlfc_fw fw_buf;
 
 	/* FCP_CMND priority support */
@@ -4708,7 +4710,6 @@ struct qla_hw_data {
 
 	struct qla_hw_data_stat stat;
 	pci_error_state_t pci_error_state;
-	u64 prev_cmd_cnt;
 	struct dma_pool *purex_dma_pool;
 	struct btree_head32 host_map;
 
@@ -4854,7 +4855,6 @@ typedef struct scsi_qla_host {
 #define SET_ZIO_THRESHOLD_NEEDED 32
 #define ISP_ABORT_TO_ROM	33
 #define VPORT_DELETE		34
-#define HEARTBEAT_CHK		38
 
 #define PROCESS_PUREX_IOCB	63
 

drivers/scsi/qla2xxx/qla_init.c

@@ -7025,12 +7025,14 @@ qla2x00_abort_isp_cleanup(scsi_qla_host_t *vha)
 	ha->chip_reset++;
 	ha->base_qpair->chip_reset = ha->chip_reset;
 	ha->base_qpair->cmd_cnt = ha->base_qpair->cmd_completion_cnt = 0;
+	ha->base_qpair->prev_completion_cnt = 0;
 	for (i = 0; i < ha->max_qpairs; i++) {
 		if (ha->queue_pair_map[i]) {
 			ha->queue_pair_map[i]->chip_reset =
 				ha->base_qpair->chip_reset;
 			ha->queue_pair_map[i]->cmd_cnt =
 			    ha->queue_pair_map[i]->cmd_completion_cnt = 0;
+			ha->base_qpair->prev_completion_cnt = 0;
 		}
 	}
 

drivers/scsi/qla2xxx/qla_os.c

@@ -2794,6 +2794,16 @@ qla2xxx_scan_finished(struct Scsi_Host *shost, unsigned long time)
 	return atomic_read(&vha->loop_state) == LOOP_READY;
 }
 
+static void qla_heartbeat_work_fn(struct work_struct *work)
+{
+	struct qla_hw_data *ha = container_of(work,
+		struct qla_hw_data, heartbeat_work);
+	struct scsi_qla_host *base_vha = pci_get_drvdata(ha->pdev);
+
+	if (!ha->flags.mbox_busy && base_vha->flags.init_done)
+		qla_no_op_mb(base_vha);
+}
+
 static void qla2x00_iocb_work_fn(struct work_struct *work)
 {
 	struct scsi_qla_host *vha = container_of(work,
@@ -3232,6 +3242,7 @@ qla2x00_probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
 	    host->transportt, sht->vendor_id);
 
 	INIT_WORK(&base_vha->iocb_work, qla2x00_iocb_work_fn);
+	INIT_WORK(&ha->heartbeat_work, qla_heartbeat_work_fn);
 
 	/* Set up the irqs */
 	ret = qla2x00_request_irqs(ha, rsp);
@@ -7118,17 +7129,6 @@ qla2x00_do_dpc(void *data)
 			qla2x00_lip_reset(base_vha);
 		}
 
-		if (test_bit(HEARTBEAT_CHK, &base_vha->dpc_flags)) {
-			/*
-			 * if there is a mb in progress then that's
-			 * enough of a check to see if fw is still ticking.
-			 */
-			if (!ha->flags.mbox_busy && base_vha->flags.init_done)
-				qla_no_op_mb(base_vha);
-
-			clear_bit(HEARTBEAT_CHK, &base_vha->dpc_flags);
-		}
-
 		ha->dpc_active = 0;
 end_loop:
 		set_current_state(TASK_INTERRUPTIBLE);
@@ -7187,57 +7187,51 @@ qla2x00_rst_aen(scsi_qla_host_t *vha)
 
 static bool qla_do_heartbeat(struct scsi_qla_host *vha)
 {
-	u64 cmd_cnt, prev_cmd_cnt;
-	bool do_hb = false;
 	struct qla_hw_data *ha = vha->hw;
-	int i;
+	u32 cmpl_cnt;
+	u16 i;
+	bool do_heartbeat = false;
 
-	/* if cmds are still pending down in fw, then do hb */
-	if (ha->base_qpair->cmd_cnt != ha->base_qpair->cmd_completion_cnt) {
-		do_hb = true;
+	/*
+	 * Allow do_heartbeat only if we don’t have any active interrupts,
+	 * but there are still IOs outstanding with firmware.
+	 */
+	cmpl_cnt = ha->base_qpair->cmd_completion_cnt;
+	if (cmpl_cnt == ha->base_qpair->prev_completion_cnt &&
+	    cmpl_cnt != ha->base_qpair->cmd_cnt) {
+		do_heartbeat = true;
 		goto skip;
 	}
+	ha->base_qpair->prev_completion_cnt = cmpl_cnt;
 
 	for (i = 0; i < ha->max_qpairs; i++) {
-		if (ha->queue_pair_map[i] &&
-		    ha->queue_pair_map[i]->cmd_cnt !=
-		    ha->queue_pair_map[i]->cmd_completion_cnt) {
-			do_hb = true;
-			break;
+		if (ha->queue_pair_map[i]) {
+			cmpl_cnt = ha->queue_pair_map[i]->cmd_completion_cnt;
+			if (cmpl_cnt == ha->queue_pair_map[i]->prev_completion_cnt &&
+			    cmpl_cnt != ha->queue_pair_map[i]->cmd_cnt) {
+				do_heartbeat = true;
+				break;
+			}
+			ha->queue_pair_map[i]->prev_completion_cnt = cmpl_cnt;
 		}
 	}
 
 skip:
-	prev_cmd_cnt = ha->prev_cmd_cnt;
-	cmd_cnt = ha->base_qpair->cmd_cnt;
-	for (i = 0; i < ha->max_qpairs; i++) {
-		if (ha->queue_pair_map[i])
-			cmd_cnt += ha->queue_pair_map[i]->cmd_cnt;
-	}
-	ha->prev_cmd_cnt = cmd_cnt;
-
-	if (!do_hb && ((cmd_cnt - prev_cmd_cnt) > 50))
-		/*
-		 * IOs are completing before periodic hb check.
-		 * IOs seems to be running, do hb for sanity check.
-		 */
-		do_hb = true;
-
-	return do_hb;
+	return do_heartbeat;
 }
 
 static void qla_heart_beat(struct scsi_qla_host *vha)
 {
+	struct qla_hw_data *ha = vha->hw;
+
 	if (vha->vp_idx)
 		return;
 
 	if (vha->hw->flags.eeh_busy || qla2x00_chip_is_down(vha))
 		return;
 
-	if (qla_do_heartbeat(vha)) {
-		set_bit(HEARTBEAT_CHK, &vha->dpc_flags);
-		qla2xxx_wake_dpc(vha);
-	}
+	if (qla_do_heartbeat(vha))
+		queue_work(ha->wq, &ha->heartbeat_work);
 }
 
 /**************************************************************************