[patch review 6/6] radio-mr800: redesign radio->users counter

[Alexey Klimov <klimov.linux@gmail.com>]

Redesign radio->users counter. Don't allow more that 5 users on radio in
usb_amradio_open() and don't stop radio device if other userspace
application uses it in usb_amradio_close().

Signed-off-by: Alexey Klimov <klimov.linux@gmail.com>

--
diff -r c2dd9da28106 linux/drivers/media/radio/radio-mr800.c
--- a/linux/drivers/media/radio/radio-mr800.c	Sat Aug 08 17:28:18 2009 +0400
+++ b/linux/drivers/media/radio/radio-mr800.c	Sat Aug 08 18:12:01 2009 +0400
@@ -540,7 +540,13 @@
 {
 	struct amradio_device *radio = video_get_drvdata(video_devdata(file));
 
-	radio->users = 1;
+	/* don't allow more than 5 users on radio */
+	if (radio->users > 4)
+		return -EBUSY;
+
+	mutex_lock(&radio->lock);
+	radio->users++;
+	mutex_unlock(&radio->lock);
 
 	return 0;
 }
@@ -554,9 +560,20 @@
 		return -ENODEV;
 
 	mutex_lock(&radio->lock);
-	radio->users = 0;
+	radio->users--;
 	mutex_unlock(&radio->lock);
 
+	/* In case several userspace applications opened the radio
+	 * and one of them closes and stops it,
+	 * we check if others use it and if they do we start the radio again. */
+	if (radio->users && radio->status == AMRADIO_STOP) {
+		int retval;
+		retval = amradio_set_mute(radio, AMRADIO_START);
+		if (retval < 0)
+			dev_warn(&radio->videodev->dev,
+				"amradio_start failed\n");
+	}
+
 	return 0;
 }
 


-- 
Best regards, Klimov Alexey