staging: unisys: visorhba: enhance visorhba to use channel_interrupt

visorhba uses kthread to obtain the responses from the IO
Service Partition periodically, on the other hand, visorbus
provides periodic work to serve such request, therefore,
kthread should be replaced by channel_interrupt.

Signed-off-by: Song Chen <chensong_2000@189.cn>
Link: https://lore.kernel.org/r/1609923863-6650-1-git-send-email-chensong_2000@189.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/unisys/visorhba/visorhba_main.c

@@ -74,14 +74,10 @@ struct visorhba_devdata {
 	unsigned long long interrupts_notme;
 	unsigned long long interrupts_disabled;
 	u64 __iomem *flags_addr;
-	atomic_t interrupt_rcvd;
-	wait_queue_head_t rsp_queue;
 	struct visordisk_info head;
 	unsigned int max_buff_len;
 	int devnum;
-	struct task_struct *thread;
-	int thread_wait_ms;
-
+	struct uiscmdrsp *cmdrsp;
 	/*
 	 * allows us to pass int handles back-and-forth between us and
 	 * iovm, instead of raw pointers
@@ -96,39 +92,6 @@ struct visorhba_devices_open {
 	struct visorhba_devdata *devdata;
 };
 
-/*
- * visor_thread_start - Starts a thread for the device
- * @threadfn:   Function the thread starts
- * @thrcontext: Context to pass to the thread, i.e. devdata
- * @name:	String describing name of thread
- *
- * Starts a thread for the device.
- *
- * Return: The task_struct * denoting the thread on success,
- *	   or NULL on failure
- */
-static struct task_struct *visor_thread_start(int (*threadfn)(void *),
-					      void *thrcontext, char *name)
-{
-	struct task_struct *task;
-
-	task = kthread_run(threadfn, thrcontext, "%s", name);
-	if (IS_ERR(task)) {
-		pr_err("visorbus failed to start thread\n");
-		return NULL;
-	}
-	return task;
-}
-
-/*
- * visor_thread_stop - Stops the thread if it is running
- * @task: Description of process to stop
- */
-static void visor_thread_stop(struct task_struct *task)
-{
-	kthread_stop(task);
-}
-
 /*
  * add_scsipending_entry - Save off io command that is pending in
  *			   Service Partition
@@ -730,7 +693,7 @@ static void visorhba_serverdown_complete(struct visorhba_devdata *devdata)
 	/* Stop using the IOVM response queue (queue should be drained
 	 * by the end)
 	 */
-	visor_thread_stop(devdata->thread);
+	visorbus_disable_channel_interrupts(devdata->dev);
 
 	/* Fail commands that weren't completed */
 	spin_lock_irqsave(&devdata->privlock, flags);
@@ -952,37 +915,18 @@ static void drain_queue(struct uiscmdrsp *cmdrsp,
 }
 
 /*
- * process_incoming_rsps - Process responses from IOSP
- * @v:  Void pointer to visorhba_devdata
- *
- * Main function for the thread that processes the responses
- * from the IO Service Partition. When the queue is empty, wait
- * to check to see if it is full again.
- *
- * Return: 0 on success, -ENOMEM on failure
+ * This is used only when this driver is active as an hba driver in the
+ * client guest partition.  It is called periodically so we can obtain
+ * and process the command respond from the IO Service Partition periodically.
  */
-static int process_incoming_rsps(void *v)
+static void visorhba_channel_interrupt(struct visor_device *dev)
 {
-	struct visorhba_devdata *devdata = v;
-	struct uiscmdrsp *cmdrsp = NULL;
-	const int size = sizeof(*cmdrsp);
+	struct visorhba_devdata *devdata = dev_get_drvdata(&dev->device);
 
-	cmdrsp = kmalloc(size, GFP_ATOMIC);
-	if (!cmdrsp)
-		return -ENOMEM;
+	if (!devdata)
+		return;
 
-	while (1) {
-		if (kthread_should_stop())
-			break;
-		wait_event_interruptible_timeout(
-			devdata->rsp_queue, (atomic_read(
-					     &devdata->interrupt_rcvd) == 1),
-				msecs_to_jiffies(devdata->thread_wait_ms));
-		/* drain queue */
-		drain_queue(cmdrsp, devdata);
-	}
-	kfree(cmdrsp);
-	return 0;
+	drain_queue(devdata->cmdrsp, devdata);
 }
 
 /*
@@ -1028,8 +972,7 @@ static int visorhba_resume(struct visor_device *dev,
 	if (devdata->serverdown && !devdata->serverchangingstate)
 		devdata->serverchangingstate = true;
 
-	devdata->thread = visor_thread_start(process_incoming_rsps, devdata,
-					     "vhba_incming");
+	visorbus_enable_channel_interrupts(dev);
 	devdata->serverdown = false;
 	devdata->serverchangingstate = false;
 
@@ -1095,7 +1038,6 @@ static int visorhba_probe(struct visor_device *dev)
 		goto err_debugfs_dir;
 	}
 
-	init_waitqueue_head(&devdata->rsp_queue);
 	spin_lock_init(&devdata->privlock);
 	devdata->serverdown = false;
 	devdata->serverchangingstate = false;
@@ -1113,9 +1055,8 @@ static int visorhba_probe(struct visor_device *dev)
 
 	idr_init(&devdata->idr);
 
-	devdata->thread_wait_ms = 2;
-	devdata->thread = visor_thread_start(process_incoming_rsps, devdata,
-					     "vhba_incoming");
+	devdata->cmdrsp = kmalloc(sizeof(*devdata->cmdrsp), GFP_ATOMIC);
+	visorbus_enable_channel_interrupts(dev);
 
 	scsi_scan_host(scsihost);
 
@@ -1150,7 +1091,8 @@ static void visorhba_remove(struct visor_device *dev)
 		return;
 
 	scsihost = devdata->scsihost;
-	visor_thread_stop(devdata->thread);
+	kfree(devdata->cmdrsp);
+	visorbus_disable_channel_interrupts(dev);
 	scsi_remove_host(scsihost);
 	scsi_host_put(scsihost);
 
@@ -1173,7 +1115,7 @@ static struct visor_driver visorhba_driver = {
 	.remove = visorhba_remove,
 	.pause = visorhba_pause,
 	.resume = visorhba_resume,
-	.channel_interrupt = NULL,
+	.channel_interrupt = visorhba_channel_interrupt,
 };
 
 /*