usb-skeleton leaking locks on open.

This weekend I was hacking around with a trivial USB driver for talking to the boot load firmware of a USB Bit Whacker. It's running the MicroChip Pic18 boot loader firmware and I'm putting together a flash program for writing new FW to the thing.

Anyway in my use of the usb-skeleton.c as my starting point I discovered my test program was getting hung up after attempting to write a buffer. The application and driver where hung in a way that required me to reboot to get it to clean up so I could try again.

It turned out the code path through skel_open can grap the driver's io_mutex lock and forget to release it.

The following patch fixes the problem for me.

--mgross

Signed-off-by Mark Gross <[email protected]>

diff -urN -X linux-2.6.23-rc7/Documentation/dontdiff linux-2.6.23-rc7/drivers/usb/usb-skeleton.c linux-2.6.23-rc7-bugfix/drivers/usb/usb-skeleton.c

drivers/usb/usb-skeleton.c +1 -1

@@ -125,6 +125,7 @@
 
 	/* save our object in the file's private structure */
 	file->private_data = dev;
+	mutex_unlock(&dev->io_mutex);
 
 exit:
 	return retval;
-

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