[PATCH v2 2/3] ibmvscsi: redo driver work thread to use enum action states

[Tyrel Datwyler]

From: Tyrel Datwyler <tyr...@linux.vnet.ibm.com>

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 <tyr...@linux.ibm.com>
---
Changes in v2:
        release/grab host_lock around reset/reenable calls

 drivers/scsi/ibmvscsi/ibmvscsi.c | 61 ++++++++++++++++++++++----------
 drivers/scsi/ibmvscsi/ibmvscsi.h |  9 +++--
 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;
-- 
2.18.1