scsi: ibmvscsi: redo driver work thread to use enum action states

The current implemenation relies on two flags in the driver's 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 <tyreld@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

2 files changed, 49 insertions, 21 deletions

diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
index 65fc8ca962c5..8df82c58e7b9 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 {
@@ -2116,48 +2116,71 @@ 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:
+                spin_unlock_irqrestore(hostdata->host->host_lock, flags);
                 rc = ibmvscsi_reset_crq_queue(&hostdata->queue, hostdata);
+                spin_lock_irqsave(hostdata->host->host_lock, flags);
                 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";
+                spin_unlock_irqrestore(hostdata->host->host_lock, flags);
                 rc = ibmvscsi_reenable_crq_queue(&hostdata->queue, hostdata);
-                hostdata->reenable_crq = 0;
+                spin_lock_irqsave(hostdata->host->host_lock, flags);
                 if (!rc)
                         rc = ibmvscsi_send_crq(hostdata, 0xC001000000000000LL, 0);
-        } else
-                return;
+                break;
+        default:
+                break;
+        }
+
+        hostdata->action = IBMVSCSI_HOST_ACTION_NONE;
 
         if (rc) {
                 atomic_set(&hostdata->request_limit, -1);
                 dev_err(hostdata->dev, "error after %s\n", action);
         }
+        spin_unlock_irqrestore(hostdata->host->host_lock, flags);
 
         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;