scsi: megaraid_sas: Add watchdog thread to detect Firmware fault

Currently driver checks for Firmware state change from ISR context, and
only when there are interrupts tied with no I/O completions.  We have seen
multiple cases where doorbell interrupts sent by firmware to indicate FW
state change are not processed by driver and it takes long time for driver
to trigger OCR. And if there are no IOs running, since we only check the FW
state as part of ISR code, fault goes undetected by driver and OCR will not
be triggered.

This patch introduces a separate workqueue that runs every one second to
detect Firmware FAULT state and trigger reset immediately.  As an
additional gain, removing PCI reads from ISR to check FW state results in
improved performance as well.
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/megaraid/megaraid_sas.h

@@ -1544,6 +1544,10 @@ enum FW_BOOT_CONTEXT {
 
 #define MR_CAN_HANDLE_64_BIT_DMA_OFFSET		(1 << 25)
 
+#define MEGASAS_WATCHDOG_THREAD_INTERVAL	1000
+#define MEGASAS_WAIT_FOR_NEXT_DMA_MSECS		20
+#define MEGASAS_WATCHDOG_WAIT_COUNT		50
+
 enum MR_ADAPTER_TYPE {
 	MFI_SERIES = 1,
 	THUNDERBOLT_SERIES = 2,
@@ -2250,7 +2254,9 @@ struct megasas_instance {
 	struct megasas_instance_template *instancet;
 	struct tasklet_struct isr_tasklet;
 	struct work_struct work_init;
-	struct work_struct crash_init;
+	struct delayed_work fw_fault_work;
+	struct workqueue_struct *fw_fault_work_q;
+	char fault_handler_work_q_name[48];
 
 	u8 flag;
 	u8 unload;
@@ -2539,7 +2545,6 @@ int megasas_get_target_prop(struct megasas_instance *instance,
 int megasas_set_crash_dump_params(struct megasas_instance *instance,
 	u8 crash_buf_state);
 void megasas_free_host_crash_buffer(struct megasas_instance *instance);
-void megasas_fusion_crash_dump_wq(struct work_struct *work);
 
 void megasas_return_cmd_fusion(struct megasas_instance *instance,
 	struct megasas_cmd_fusion *cmd);
@@ -2560,6 +2565,9 @@ int megasas_reset_target_fusion(struct scsi_cmnd *scmd);
 u32 mega_mod64(u64 dividend, u32 divisor);
 int megasas_alloc_fusion_context(struct megasas_instance *instance);
 void megasas_free_fusion_context(struct megasas_instance *instance);
+int megasas_fusion_start_watchdog(struct megasas_instance *instance);
+void megasas_fusion_stop_watchdog(struct megasas_instance *instance);
+
 void megasas_set_dma_settings(struct megasas_instance *instance,
 			      struct megasas_dcmd_frame *dcmd,
 			      dma_addr_t dma_addr, u32 dma_len);

drivers/scsi/megaraid/megaraid_sas_base.c

@@ -5582,8 +5582,20 @@ static int megasas_init_fw(struct megasas_instance *instance)
 			instance->skip_heartbeat_timer_del = 1;
 	}
 
+	/*
+	 * Create and start watchdog thread which will monitor
+	 * controller state every 1 sec and trigger OCR when
+	 * it enters fault state
+	 */
+	if (instance->adapter_type != MFI_SERIES)
+		if (megasas_fusion_start_watchdog(instance) != SUCCESS)
+			goto fail_start_watchdog;
+
 	return 0;
 
+fail_start_watchdog:
+	if (instance->requestorId && !instance->skip_heartbeat_timer_del)
+		del_timer_sync(&instance->sriov_heartbeat_timer);
 fail_get_ld_pd_list:
 	instance->instancet->disable_intr(instance);
 fail_init_adapter:
@@ -6434,12 +6446,10 @@ static inline void megasas_init_ctrl_params(struct megasas_instance *instance)
 	instance->disableOnlineCtrlReset = 1;
 	instance->UnevenSpanSupport = 0;
 
-	if (instance->adapter_type != MFI_SERIES) {
+	if (instance->adapter_type != MFI_SERIES)
 		INIT_WORK(&instance->work_init, megasas_fusion_ocr_wq);
-		INIT_WORK(&instance->crash_init, megasas_fusion_crash_dump_wq);
-	} else {
+	else
 		INIT_WORK(&instance->work_init, process_fw_state_change_wq);
-	}
 }
 
 /**
@@ -6708,6 +6718,10 @@ megasas_suspend(struct pci_dev *pdev, pm_message_t state)
 	if (instance->requestorId && !instance->skip_heartbeat_timer_del)
 		del_timer_sync(&instance->sriov_heartbeat_timer);
 
+	/* Stop the FW fault detection watchdog */
+	if (instance->adapter_type != MFI_SERIES)
+		megasas_fusion_stop_watchdog(instance);
+
 	megasas_flush_cache(instance);
 	megasas_shutdown_controller(instance, MR_DCMD_HIBERNATE_SHUTDOWN);
 
@@ -6843,8 +6857,16 @@ megasas_resume(struct pci_dev *pdev)
 	if (megasas_start_aen(instance))
 		dev_err(&instance->pdev->dev, "Start AEN failed\n");
 
+	/* Re-launch FW fault watchdog */
+	if (instance->adapter_type != MFI_SERIES)
+		if (megasas_fusion_start_watchdog(instance) != SUCCESS)
+			goto fail_start_watchdog;
+
 	return 0;
 
+fail_start_watchdog:
+	if (instance->requestorId && !instance->skip_heartbeat_timer_del)
+		del_timer_sync(&instance->sriov_heartbeat_timer);
 fail_init_mfi:
 	megasas_free_ctrl_dma_buffers(instance);
 	megasas_free_ctrl_mem(instance);
@@ -6912,6 +6934,10 @@ static void megasas_detach_one(struct pci_dev *pdev)
 	if (instance->requestorId && !instance->skip_heartbeat_timer_del)
 		del_timer_sync(&instance->sriov_heartbeat_timer);
 
+	/* Stop the FW fault detection watchdog */
+	if (instance->adapter_type != MFI_SERIES)
+		megasas_fusion_stop_watchdog(instance);
+
 	if (instance->fw_crash_state != UNAVAILABLE)
 		megasas_free_host_crash_buffer(instance);
 	scsi_remove_host(instance->host);

drivers/scsi/megaraid/megaraid_sas_fusion.c

@@ -48,6 +48,7 @@
 #include <linux/mutex.h>
 #include <linux/poll.h>
 #include <linux/vmalloc.h>
+#include <linux/workqueue.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_cmnd.h>
@@ -95,6 +96,7 @@ static void megasas_free_rdpq_fusion(struct megasas_instance *instance);
 static void megasas_free_reply_fusion(struct megasas_instance *instance);
 static inline
 void megasas_configure_queue_sizes(struct megasas_instance *instance);
+static void megasas_fusion_crash_dump(struct megasas_instance *instance);
 
 /**
  * megasas_check_same_4gb_region -	check if allocation
@@ -1759,6 +1761,90 @@ megasas_init_adapter_fusion(struct megasas_instance *instance)
 	return 1;
 }
 
+/**
+ * megasas_fault_detect_work	-	Worker function of
+ *					FW fault handling workqueue.
+ */
+static void
+megasas_fault_detect_work(struct work_struct *work)
+{
+	struct megasas_instance *instance =
+		container_of(work, struct megasas_instance,
+			     fw_fault_work.work);
+	u32 fw_state, dma_state, status;
+
+	/* Check the fw state */
+	fw_state = instance->instancet->read_fw_status_reg(instance->reg_set) &
+			MFI_STATE_MASK;
+
+	if (fw_state == MFI_STATE_FAULT) {
+		dma_state = instance->instancet->read_fw_status_reg(
+				instance->reg_set) & MFI_STATE_DMADONE;
+		/* Start collecting crash, if DMA bit is done */
+		if (instance->crash_dump_drv_support &&
+		    instance->crash_dump_app_support && dma_state) {
+			megasas_fusion_crash_dump(instance);
+		} else {
+			if (instance->unload == 0) {
+				status = megasas_reset_fusion(instance->host, 0);
+				if (status != SUCCESS) {
+					dev_err(&instance->pdev->dev,
+						"Failed from %s %d, do not re-arm timer\n",
+						__func__, __LINE__);
+					return;
+				}
+			}
+		}
+	}
+
+	if (instance->fw_fault_work_q)
+		queue_delayed_work(instance->fw_fault_work_q,
+			&instance->fw_fault_work,
+			msecs_to_jiffies(MEGASAS_WATCHDOG_THREAD_INTERVAL));
+}
+
+int
+megasas_fusion_start_watchdog(struct megasas_instance *instance)
+{
+	/* Check if the Fault WQ is already started */
+	if (instance->fw_fault_work_q)
+		return SUCCESS;
+
+	INIT_DELAYED_WORK(&instance->fw_fault_work, megasas_fault_detect_work);
+
+	snprintf(instance->fault_handler_work_q_name,
+		 sizeof(instance->fault_handler_work_q_name),
+		 "poll_megasas%d_status", instance->host->host_no);
+
+	instance->fw_fault_work_q =
+		create_singlethread_workqueue(instance->fault_handler_work_q_name);
+	if (!instance->fw_fault_work_q) {
+		dev_err(&instance->pdev->dev, "Failed from %s %d\n",
+			__func__, __LINE__);
+		return FAILED;
+	}
+
+	queue_delayed_work(instance->fw_fault_work_q,
+			   &instance->fw_fault_work,
+			   msecs_to_jiffies(MEGASAS_WATCHDOG_THREAD_INTERVAL));
+
+	return SUCCESS;
+}
+
+void
+megasas_fusion_stop_watchdog(struct megasas_instance *instance)
+{
+	struct workqueue_struct *wq;
+
+	if (instance->fw_fault_work_q) {
+		wq = instance->fw_fault_work_q;
+		instance->fw_fault_work_q = NULL;
+		if (!cancel_delayed_work_sync(&instance->fw_fault_work))
+			flush_workqueue(wq);
+		destroy_workqueue(wq);
+	}
+}
+
 /**
  * map_cmd_status -	Maps FW cmd status to OS cmd status
  * @cmd :		Pointer to cmd
@@ -3525,7 +3611,7 @@ irqreturn_t megasas_isr_fusion(int irq, void *devp)
 {
 	struct megasas_irq_context *irq_context = devp;
 	struct megasas_instance *instance = irq_context->instance;
-	u32 mfiStatus, fw_state, dma_state;
+	u32 mfiStatus;
 
 	if (instance->mask_interrupts)
 		return IRQ_NONE;
@@ -3542,31 +3628,7 @@ irqreturn_t megasas_isr_fusion(int irq, void *devp)
 		return IRQ_HANDLED;
 	}
 
-	if (!complete_cmd_fusion(instance, irq_context->MSIxIndex)) {
-		instance->instancet->clear_intr(instance->reg_set);
-		/* If we didn't complete any commands, check for FW fault */
-		fw_state = instance->instancet->read_fw_status_reg(
-			instance->reg_set) & MFI_STATE_MASK;
-		dma_state = instance->instancet->read_fw_status_reg
-			(instance->reg_set) & MFI_STATE_DMADONE;
-		if (instance->crash_dump_drv_support &&
-			instance->crash_dump_app_support) {
-			/* Start collecting crash, if DMA bit is done */
-			if ((fw_state == MFI_STATE_FAULT) && dma_state)
-				schedule_work(&instance->crash_init);
-			else if (fw_state == MFI_STATE_FAULT) {
-				if (instance->unload == 0)
-					schedule_work(&instance->work_init);
-			}
-		} else if (fw_state == MFI_STATE_FAULT) {
-			dev_warn(&instance->pdev->dev, "Iop2SysDoorbellInt"
-			       "for scsi%d\n", instance->host->host_no);
-			if (instance->unload == 0)
-				schedule_work(&instance->work_init);
-		}
-	}
-
-	return IRQ_HANDLED;
+	return complete_cmd_fusion(instance, irq_context->MSIxIndex);
 }
 
 /**
@@ -4752,13 +4814,12 @@ int megasas_reset_fusion(struct Scsi_Host *shost, int reason)
 	return retval;
 }
 
-/* Fusion Crash dump collection work queue */
-void  megasas_fusion_crash_dump_wq(struct work_struct *work)
+/* Fusion Crash dump collection */
+void  megasas_fusion_crash_dump(struct megasas_instance *instance)
 {
-	struct megasas_instance *instance =
-		container_of(work, struct megasas_instance, crash_init);
 	u32 status_reg;
 	u8 partial_copy = 0;
+	int wait = 0;
 
 
 	status_reg = instance->instancet->read_fw_status_reg(instance->reg_set);
@@ -4786,21 +4847,42 @@ void  megasas_fusion_crash_dump_wq(struct work_struct *work)
 			"allocated: %d\n", instance->drv_buf_alloc);
 	}
 
-	/*
-	 * Driver has allocated max buffers, which can be allocated
-	 * and FW has more crash dump data, then driver will
-	 * ignore the data.
-	 */
-	if (instance->drv_buf_index >= (instance->drv_buf_alloc)) {
-		dev_info(&instance->pdev->dev, "Driver is done copying "
-			"the buffer: %d\n", instance->drv_buf_alloc);
-		status_reg |= MFI_STATE_CRASH_DUMP_DONE;
-		partial_copy = 1;
-	} else {
-		memcpy(instance->crash_buf[instance->drv_buf_index],
-			instance->crash_dump_buf, CRASH_DMA_BUF_SIZE);
-		instance->drv_buf_index++;
-		status_reg &= ~MFI_STATE_DMADONE;
+	while (!(status_reg & MFI_STATE_CRASH_DUMP_DONE) &&
+	       (wait < MEGASAS_WATCHDOG_WAIT_COUNT)) {
+		if (!(status_reg & MFI_STATE_DMADONE)) {
+			/*
+			 * Next crash dump buffer is not yet DMA'd by FW
+			 * Check after 10ms. Wait for 1 second for FW to
+			 * post the next buffer. If not bail out.
+			 */
+			wait++;
+			msleep(MEGASAS_WAIT_FOR_NEXT_DMA_MSECS);
+			status_reg = instance->instancet->read_fw_status_reg(
+					instance->reg_set);
+			continue;
+		}
+
+		wait = 0;
+		if (instance->drv_buf_index >= instance->drv_buf_alloc) {
+			dev_info(&instance->pdev->dev,
+				 "Driver is done copying the buffer: %d\n",
+				 instance->drv_buf_alloc);
+			status_reg |= MFI_STATE_CRASH_DUMP_DONE;
+			partial_copy = 1;
+			break;
+		} else {
+			memcpy(instance->crash_buf[instance->drv_buf_index],
+			       instance->crash_dump_buf, CRASH_DMA_BUF_SIZE);
+			instance->drv_buf_index++;
+			status_reg &= ~MFI_STATE_DMADONE;
+		}
+
+		writel(status_reg, &instance->reg_set->outbound_scratch_pad);
+		readl(&instance->reg_set->outbound_scratch_pad);
+
+		msleep(MEGASAS_WAIT_FOR_NEXT_DMA_MSECS);
+		status_reg = instance->instancet->read_fw_status_reg(
+				instance->reg_set);
 	}
 
 	if (status_reg & MFI_STATE_CRASH_DUMP_DONE) {
@@ -4813,9 +4895,6 @@ void  megasas_fusion_crash_dump_wq(struct work_struct *work)
 		readl(&instance->reg_set->outbound_scratch_pad);
 		if (!partial_copy)
 			megasas_reset_fusion(instance->host, 0);
-	} else {
-		writel(status_reg, &instance->reg_set->outbound_scratch_pad);
-		readl(&instance->reg_set->outbound_scratch_pad);
 	}
 }