scsi: smartpqi: Update LUN reset handler

Enhance check for commands queued to the controller.  Add new function
pqi_nonempty_inbound_queue_count() that will wait for all I/O queued for
submission to controller across all queue groups to drain.  Add helper
functions to obtain queue command counts for each queue group.  These
queues should drain quickly as they are already staged to be submitted down
to the controller's IB queue.

Enhance check for outstanding command completion.  Update the count of
outstanding commands while waiting.  This value was not re-obtained and was
potentially causing infinite wait for all completions.

Link: https://lore.kernel.org/r/20210928235442.201875-5-don.brace@microchip.com
Reviewed-by: Scott Benesh <scott.benesh@microchip.com>
Reviewed-by: Scott Teel <scott.teel@microchip.com>
Reviewed-by: Mike McGowen <mike.mcgowen@microchip.com>
Acked-by: John Donnelly <john.p.donnelly@oracle.com>
Signed-off-by: Kevin Barnett <kevin.barnett@microchip.com>
Signed-off-by: Don Brace <don.brace@microchip.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/smartpqi/smartpqi_init.c

@@ -5799,64 +5799,91 @@ static int pqi_scsi_queue_command(struct Scsi_Host *shost, struct scsi_cmnd *scm
 	return rc;
 }
 
-static int pqi_wait_until_queued_io_drained(struct pqi_ctrl_info *ctrl_info,
-	struct pqi_queue_group *queue_group)
+static unsigned int pqi_queued_io_count(struct pqi_ctrl_info *ctrl_info)
 {
+	unsigned int i;
 	unsigned int path;
 	unsigned long flags;
-	bool list_is_empty;
+	unsigned int queued_io_count;
+	struct pqi_queue_group *queue_group;
+	struct pqi_io_request *io_request;
 
-	for (path = 0; path < 2; path++) {
-		while (1) {
-			spin_lock_irqsave(
-				&queue_group->submit_lock[path], flags);
-			list_is_empty =
-				list_empty(&queue_group->request_list[path]);
-			spin_unlock_irqrestore(
-				&queue_group->submit_lock[path], flags);
-			if (list_is_empty)
-				break;
-			pqi_check_ctrl_health(ctrl_info);
-			if (pqi_ctrl_offline(ctrl_info))
-				return -ENXIO;
-			usleep_range(1000, 2000);
+	queued_io_count = 0;
+
+	for (i = 0; i < ctrl_info->num_queue_groups; i++) {
+		queue_group = &ctrl_info->queue_groups[i];
+		for (path = 0; path < 2; path++) {
+			spin_lock_irqsave(&queue_group->submit_lock[path], flags);
+			list_for_each_entry(io_request, &queue_group->request_list[path], request_list_entry)
+				queued_io_count++;
+			spin_unlock_irqrestore(&queue_group->submit_lock[path], flags);
 		}
 	}
 
-	return 0;
+	return queued_io_count;
 }
 
-static int pqi_wait_until_inbound_queues_empty(struct pqi_ctrl_info *ctrl_info)
+static unsigned int pqi_nonempty_inbound_queue_count(struct pqi_ctrl_info *ctrl_info)
 {
-	int rc;
 	unsigned int i;
 	unsigned int path;
+	unsigned int nonempty_inbound_queue_count;
 	struct pqi_queue_group *queue_group;
 	pqi_index_t iq_pi;
 	pqi_index_t iq_ci;
 
+	nonempty_inbound_queue_count = 0;
+
 	for (i = 0; i < ctrl_info->num_queue_groups; i++) {
 		queue_group = &ctrl_info->queue_groups[i];
-
-		rc = pqi_wait_until_queued_io_drained(ctrl_info, queue_group);
-		if (rc)
-			return rc;
-
 		for (path = 0; path < 2; path++) {
 			iq_pi = queue_group->iq_pi_copy[path];
+			iq_ci = readl(queue_group->iq_ci[path]);
+			if (iq_ci != iq_pi)
+				nonempty_inbound_queue_count++;
+		}
+	}
 
-			while (1) {
-				iq_ci = readl(queue_group->iq_ci[path]);
-				if (iq_ci == iq_pi)
-					break;
-				pqi_check_ctrl_health(ctrl_info);
-				if (pqi_ctrl_offline(ctrl_info))
-					return -ENXIO;
-				usleep_range(1000, 2000);
-			}
+	return nonempty_inbound_queue_count;
+}
+
+#define PQI_INBOUND_QUEUES_NONEMPTY_WARNING_TIMEOUT_SECS	10
+
+static int pqi_wait_until_inbound_queues_empty(struct pqi_ctrl_info *ctrl_info)
+{
+	unsigned long start_jiffies;
+	unsigned long warning_timeout;
+	unsigned int queued_io_count;
+	unsigned int nonempty_inbound_queue_count;
+	bool displayed_warning;
+
+	displayed_warning = false;
+	start_jiffies = jiffies;
+	warning_timeout = (PQI_INBOUND_QUEUES_NONEMPTY_WARNING_TIMEOUT_SECS * PQI_HZ) + start_jiffies;
+
+	while (1) {
+		queued_io_count = pqi_queued_io_count(ctrl_info);
+		nonempty_inbound_queue_count = pqi_nonempty_inbound_queue_count(ctrl_info);
+		if (queued_io_count == 0 && nonempty_inbound_queue_count == 0)
+			break;
+		pqi_check_ctrl_health(ctrl_info);
+		if (pqi_ctrl_offline(ctrl_info))
+			return -ENXIO;
+		if (time_after(jiffies, warning_timeout)) {
+			dev_warn(&ctrl_info->pci_dev->dev,
+				"waiting %u seconds for queued I/O to drain (queued I/O count: %u; non-empty inbound queue count: %u)\n",
+				jiffies_to_msecs(jiffies - start_jiffies) / 1000, queued_io_count, nonempty_inbound_queue_count);
+			displayed_warning = true;
+			warning_timeout = (PQI_INBOUND_QUEUES_NONEMPTY_WARNING_TIMEOUT_SECS * PQI_HZ) + jiffies;
 		}
+		usleep_range(1000, 2000);
 	}
 
+	if (displayed_warning)
+		dev_warn(&ctrl_info->pci_dev->dev,
+			"queued I/O drained after waiting for %u seconds\n",
+			jiffies_to_msecs(jiffies - start_jiffies) / 1000);
+
 	return 0;
 }
 
@@ -5922,7 +5949,7 @@ static int pqi_device_wait_for_pending_io(struct pqi_ctrl_info *ctrl_info,
 		if (pqi_ctrl_offline(ctrl_info))
 			return -ENXIO;
 		msecs_waiting = jiffies_to_msecs(jiffies - start_jiffies);
-		if (msecs_waiting > timeout_msecs) {
+		if (msecs_waiting >= timeout_msecs) {
 			dev_err(&ctrl_info->pci_dev->dev,
 				"scsi %d:%d:%d:%d: timed out after %lu seconds waiting for %d outstanding command(s)\n",
 				ctrl_info->scsi_host->host_no, device->bus, device->target,
@@ -5957,6 +5984,7 @@ static int pqi_wait_for_lun_reset_completion(struct pqi_ctrl_info *ctrl_info,
 {
 	int rc;
 	unsigned int wait_secs;
+	int cmds_outstanding;
 
 	wait_secs = 0;
 
@@ -5974,11 +6002,10 @@ static int pqi_wait_for_lun_reset_completion(struct pqi_ctrl_info *ctrl_info,
 		}
 
 		wait_secs += PQI_LUN_RESET_POLL_COMPLETION_SECS;
-
+		cmds_outstanding = atomic_read(&device->scsi_cmds_outstanding);
 		dev_warn(&ctrl_info->pci_dev->dev,
-			"scsi %d:%d:%d:%d: waiting %u seconds for LUN reset to complete\n",
-			ctrl_info->scsi_host->host_no, device->bus, device->target, device->lun,
-			wait_secs);
+			"scsi %d:%d:%d:%d: waiting %u seconds for LUN reset to complete (%d command(s) outstanding)\n",
+			ctrl_info->scsi_host->host_no, device->bus, device->target, device->lun, wait_secs, cmds_outstanding);
 	}
 
 	return rc;