El Tue, Dec 04, 2007 at 11:09:02AM -0800 Daniel Walker ha dit:
On Tue, 2007-12-04 at 17:55 +0100, Matthias Kaehlcke wrote:
@@ -1990,7 +1991,7 @@ static void usbtest_disconnect (struct
usb_interface *intf)
{
struct usbtest_dev *dev = usb_get_intfdata (intf);
- down (dev-sem);
+ mutex_lock(dev-lock);
usb_set_intfdata (intf, NULL);
dev_dbg (intf-dev, disconnect\n);
This looks like a bit of an anomaly.. The code that isn't shown above is
the kfree(dev) .. So this isn't legal since it's freeing a locked
mutex. Here's a excerpt from the comment above mutex_lock(),
* The mutex must later on be released by the same task that
* acquired it. Recursive locking is not allowed. The task
* may not exit without first unlocking the mutex. Also, kernel
* memory where the mutex resides mutex must not be freed with
* the mutex still locked. The mutex must first be initialized
* (or statically defined) before it can be locked. memset()-ing
* the mutex to 0 is not allowed.
you're absolutely right that freeing a locked mutex isn't a good idea
thanks for pointing it out!
--
Matthias Kaehlcke
Linux System Developer
Barcelona
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Don't walk in front of me, I may not follow
Just walk beside me and be my friend
(Albert Camus)
.''`.
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