Subject: [PATCH 2/3] ibmvscsi: redo driver work thread to use enum action states

From: Tyrel Datwyler <[email-masked]>
Date: Wed, 1 May 2019 19:47:28 -0500

From: Tyrel Datwyler <[email-masked]>

The current implemenation relies on two flags in the drivers private host
structure to signal the need for a host reset or to reenable the CRQ after a
LPAR migration. This patch does away with those flags and introduces a single
action flag and defined enums for the supported kthread work actions. Lastly,
the if/else logic is replaced with a switch statement.

Signed-off-by: Tyrel Datwyler <[email-masked]>
---
 drivers/scsi/ibmvscsi/ibmvscsi.c | 57 +++++++++++++++++++++-----------
 drivers/scsi/ibmvscsi/ibmvscsi.h |  9 +++--
 2 files changed, 45 insertions(+), 21 deletions(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index 1c37244f16a0..683139e6c63f 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -828,7 +828,7 @@ static void ibmvscsi_reset_host(struct ibmvscsi_host_data *hostdata)
 	atomic_set(&hostdata->request_limit, 0);
 
 	purge_requests(hostdata, DID_ERROR);
-	hostdata->reset_crq = 1;
+	hostdata->action = IBMVSCSI_HOST_ACTION_RESET;
 	wake_up(&hostdata->work_wait_q);
 }
 
@@ -1797,7 +1797,7 @@ static void ibmvscsi_handle_crq(struct viosrp_crq *crq,
 			/* We need to re-setup the interpartition connection */
 			dev_info(hostdata->dev, "Re-enabling adapter!\n");
 			hostdata->client_migrated = 1;
-			hostdata->reenable_crq = 1;
+			hostdata->action = IBMVSCSI_HOST_ACTION_REENABLE;
 			purge_requests(hostdata, DID_REQUEUE);
 			wake_up(&hostdata->work_wait_q);
 		} else {
@@ -2118,26 +2118,32 @@ static unsigned long ibmvscsi_get_desired_dma(struct vio_dev *vdev)
 
 static void ibmvscsi_do_work(struct ibmvscsi_host_data *hostdata)
 {
+	unsigned long flags;
 	int rc;
 	char *action = "reset";
 
-	if (hostdata->reset_crq) {
-		smp_rmb();
-		hostdata->reset_crq = 0;
-
+	spin_lock_irqsave(hostdata->host->host_lock, flags);
+	switch (hostdata->action) {
+	case IBMVSCSI_HOST_ACTION_NONE:
+		break;
+	case IBMVSCSI_HOST_ACTION_RESET:
 		rc = ibmvscsi_reset_crq_queue(&hostdata->queue, hostdata);
 		if (!rc)
 			rc = ibmvscsi_send_crq(hostdata, 0xC001000000000000LL, 0);
 		vio_enable_interrupts(to_vio_dev(hostdata->dev));
-	} else if (hostdata->reenable_crq) {
-		smp_rmb();
+		break;
+	case IBMVSCSI_HOST_ACTION_REENABLE:
 		action = "enable";
 		rc = ibmvscsi_reenable_crq_queue(&hostdata->queue, hostdata);
-		hostdata->reenable_crq = 0;
 		if (!rc)
 			rc = ibmvscsi_send_crq(hostdata, 0xC001000000000000LL, 0);
-	} else
-		return;
+		break;
+	default:
+		break;
+	}
+
+	hostdata->action = IBMVSCSI_HOST_ACTION_NONE;
+	spin_unlock_irqrestore(hostdata->host->host_lock, flags);
 
 	if (rc) {
 		atomic_set(&hostdata->request_limit, -1);
@@ -2147,19 +2153,32 @@ static void ibmvscsi_do_work(struct ibmvscsi_host_data *hostdata)
 	scsi_unblock_requests(hostdata->host);
 }
 
-static int ibmvscsi_work_to_do(struct ibmvscsi_host_data *hostdata)
+static int __ibmvscsi_work_to_do(struct ibmvscsi_host_data *hostdata)
 {
 	if (kthread_should_stop())
 		return 1;
-	else if (hostdata->reset_crq) {
-		smp_rmb();
-		return 1;
-	} else if (hostdata->reenable_crq) {
-		smp_rmb();
-		return 1;
+	switch (hostdata->action) {
+	case IBMVSCSI_HOST_ACTION_NONE:
+		return 0;
+	case IBMVSCSI_HOST_ACTION_RESET:
+	case IBMVSCSI_HOST_ACTION_REENABLE:
+	default:
+		break;
 	}
 
-	return 0;
+	return 1;
+}
+
+static int ibmvscsi_work_to_do(struct ibmvscsi_host_data *hostdata)
+{
+	unsigned long flags;
+	int rc;
+
+	spin_lock_irqsave(hostdata->host->host_lock, flags);
+	rc = __ibmvscsi_work_to_do(hostdata);
+	spin_unlock_irqrestore(hostdata->host->host_lock, flags);
+
+	return rc;
 }
 
 static int ibmvscsi_work(void *data)
diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.h b/drivers/scsi/ibmvscsi/ibmvscsi.h
index 3a7875575616..04bcbc832dc9 100644
--- a/drivers/scsi/ibmvscsi/ibmvscsi.h
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.h
@@ -88,13 +88,18 @@ struct event_pool {
 	dma_addr_t iu_token;
 };
 
+enum ibmvscsi_host_action {
+	IBMVSCSI_HOST_ACTION_NONE = 0,
+	IBMVSCSI_HOST_ACTION_RESET,
+	IBMVSCSI_HOST_ACTION_REENABLE,
+};
+
 /* all driver data associated with a host adapter */
 struct ibmvscsi_host_data {
 	struct list_head host_list;
 	atomic_t request_limit;
 	int client_migrated;
-	int reset_crq;
-	int reenable_crq;
+	enum ibmvscsi_host_action action;
 	struct device *dev;
 	struct event_pool pool;
 	struct crq_queue queue;
-- 
2.18.1