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radio-mr800: remove redundant lock/unlock_kernel

PATCH In review Alexey Klimov 2 participants 2 messages Aug 8, 2009 – Aug 10, 2009 Media (V4L/DVB)

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Alexey Klimov

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#0 lore raw

PATCH 1/6 radio-mr800: remove redundant lock/unlock_kernel

Remove redundant lock/unlock_kernel() calls from usb_amradio_open/close functions.

Signed-off-by Alexey Klimov <[email protected]>

--

linux/drivers/media/radio/radio-mr800.c +0 -4
diff -r ee6cf88cb5d3 linux/drivers/media/radio/radio-mr800.c
@@ -540,8 +540,6 @@
 	struct amradio_device *radio = video_get_drvdata(video_devdata(file));
 	int retval;
 
-	lock_kernel();
-
 	radio->users = 1;
 	radio->muted = 1;
 

@@ -550,7 +548,6 @@
 		amradio_dev_warn(&radio->videodev->dev,
 			"radio did not start up properly\n");
 		radio->users = 0;
-		unlock_kernel();
 		return -EIO;
 	}
 

@@ -564,7 +561,6 @@
 		amradio_dev_warn(&radio->videodev->dev,
 			"set frequency failed\n");
 
-	unlock_kernel();
 	return 0;
 }
Signature · 1 line
Best regards, Klimov Alexey
#1 lore raw
Quoted 10 lines · Alexey Klimov

Remove redundant lock/unlock_kernel() calls from usb_amradio_open/close functions.

Signed-off-by Alexey Klimov <[email protected]>

--
diff -r ee6cf88cb5d3 linux/drivers/media/radio/radio-mr800.c

linux/drivers/media/radio/radio-mr800.c   Wed Jul 29 10:44:02 2009 +0400 line 544

Quoted 5 lines
linux/drivers/media/radio/radio-mr800.c   Wed Jul 29 10:44:02 2009 +0400 renamed from linux/drivers/media/radio/radio-mr800.c   Wed Jul 29 01:42:02 2009 -0300 +0 -2
@@ -540,8 +540,6 @@
        struct amradio_device *radio = video_get_drvdata(video_devdata(file));
        int retval;
 
-       lock_kernel();
-

Maybe I'm missing something here, but the lock_kernel() call seems very necessary here since you're modifying the state of the driver without taking the driver's lock. Last I checked the v4l2 subsystem doesn't call open with it's lock held. So by removing these locks you've introduced a race condition between open and close.

Quoted 22 lines
linux/drivers/media/radio/radio-mr800.c   Wed Jul 29 10:44:02 2009 +0400 renamed from linux/drivers/media/radio/radio-mr800.c   Wed Jul 29 01:42:02 2009 -0300 +0 -3
        radio->users = 1;
        radio->muted = 1;
 

@@ -550,7 +548,6 @@
                amradio_dev_warn(&radio->videodev->dev,
                        "radio did not start up properly\n");
                radio->users = 0;
-               unlock_kernel();
                return -EIO;
        }
 

@@ -564,7 +561,6 @@
                amradio_dev_warn(&radio->videodev->dev,
                        "set frequency failed\n");
 
-       unlock_kernel();
        return 0;
  }
 
 
 
--
Quoted 2 lines

Best regards, Klimov Alexey

Regards,

David Ellingsworth