cx18: Change to singlethreaded global work queue thread for deferable work

From: Andy Walls <awalls@radix.net>

Change to singlethreaded global work queue thread for deferable work,
instead of the kernel default multithreaded work queue.  This ensures
execution of deferable work is always in the proper order, so caputred buffers
don't get reordered.

Priority: normal

Signed-off-by: Andy Walls <awalls@radix.net>

3 files changed, 26 insertions, 2 deletions

diff --git a/linux/drivers/media/video/cx18/cx18-driver.c b/linux/drivers/media/video/cx18/cx18-driver.c
index 725ed2847..61f0ea9d3 100644
--- a/linux/drivers/media/video/cx18/cx18-driver.c
+++ b/linux/drivers/media/video/cx18/cx18-driver.c
@@ -56,6 +56,9 @@ struct cx18 *cx18_cards[CX18_MAX_CARDS];
 /* Protects cx18_cards_active */
 DEFINE_SPINLOCK(cx18_cards_lock);
 
+/* Queue for deferrable IRQ handling work for all cx18 cards in system */
+struct workqueue_struct *cx18_work_queue;
+
 /* add your revision and whatnot here */
 static struct pci_device_id cx18_pci_tbl[] __devinitdata = {
 	{PCI_VENDOR_ID_CX, PCI_DEVICE_ID_CX23418,
@@ -925,6 +928,13 @@ int cx18_init_on_first_open(struct cx18 *cx)
 	return 0;
 }
 
+static void cx18_cancel_epu_work_orders(struct cx18 *cx)
+{
+	int i;
+	for (i = 0; i < CX18_MAX_EPU_WORK_ORDERS; i++)
+		cancel_work_sync(&cx->epu_work_order[i].work);
+}
+
 static void cx18_remove(struct pci_dev *pci_dev)
 {
 	struct cx18 *cx = pci_get_drvdata(pci_dev);
@@ -942,7 +952,7 @@ static void cx18_remove(struct pci_dev *pci_dev)
 
 	cx18_halt_firmware(cx);
 
-	flush_scheduled_work();
+	cx18_cancel_epu_work_orders(cx);
 
 	cx18_streams_cleanup(cx, 1);
 
@@ -986,8 +996,17 @@ static int module_start(void)
 		printk(KERN_INFO "cx18:   Debug value must be >= 0 and <= 511!\n");
 	}
 
+	cx18_work_queue = create_singlethread_workqueue("cx18");
+	if (cx18_work_queue == NULL) {
+		printk(KERN_ERR
+		       "cx18:   Unable to create work hander thread\n");
+		return -ENOMEM;
+	}
+
 	if (pci_register_driver(&cx18_pci_driver)) {
 		printk(KERN_ERR "cx18:   Error detecting PCI card\n");
+		destroy_workqueue(cx18_work_queue);
+		cx18_work_queue = NULL;
 		return -ENODEV;
 	}
 	printk(KERN_INFO "cx18:  End initialization\n");
@@ -1000,11 +1019,15 @@ static void module_cleanup(void)
 
 	pci_unregister_driver(&cx18_pci_driver);
 
+	destroy_workqueue(cx18_work_queue);
+	cx18_work_queue = NULL;
+
 	for (i = 0; i < cx18_cards_active; i++) {
 		if (cx18_cards[i] == NULL)
 			continue;
 		kfree(cx18_cards[i]);
 	}
+
 }
 
 module_init(module_start);
diff --git a/linux/drivers/media/video/cx18/cx18-driver.h b/linux/drivers/media/video/cx18/cx18-driver.h
index 5ebf84b78..f8929eb72 100644
--- a/linux/drivers/media/video/cx18/cx18-driver.h
+++ b/linux/drivers/media/video/cx18/cx18-driver.h
@@ -486,6 +486,7 @@ extern struct cx18 *cx18_cards[];
 extern int cx18_cards_active;
 extern int cx18_first_minor;
 extern spinlock_t cx18_cards_lock;
+extern struct workqueue_struct *cx18_work_queue;
 
 /*==============Prototypes==================*/
 
diff --git a/linux/drivers/media/video/cx18/cx18-mailbox.c b/linux/drivers/media/video/cx18/cx18-mailbox.c
index c13d02646..703aaab69 100644
--- a/linux/drivers/media/video/cx18/cx18-mailbox.c
+++ b/linux/drivers/media/video/cx18/cx18-mailbox.c
@@ -415,7 +415,7 @@ void cx18_api_epu_cmd_irq(struct cx18 *cx, int rpu)
 	 */
 	submit = epu_cmd_irq(cx, order, stale);
 	if (submit > 0) {
-		schedule_work(&order->work);
+		queue_work(cx18_work_queue, &order->work);
 	}
 }