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| author | Alan Stern <stern@rowland.harvard.edu> | 2005-08-11 10:15:39 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2005-09-08 16:28:21 -0700 |
| commit | 3ea15966ed59f2bc20928c7b0496b4585f6de206 (patch) | |
| tree | 45c392aa393fe4ad245b6593b5a74f212f010637 /drivers | |
| parent | e52b1d3afe698cb77c080ecbe9e745257ff8c81b (diff) | |
| download | linux-3ea15966ed59f2bc20928c7b0496b4585f6de206.tar.gz | |
[PATCH] USB: Add timeout to usb_lock_device_for_reset
This patch (as555) modifies the already-awkward
usb_lock_device_for_reset routine in usbcore by adding a timeout. The
whole point of the routine is that the caller wants to acquire some
semaphores in the wrong order; protecting against the possibility of
deadlock by timing out seems only prudent.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/usb/core/usb.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c index bc966dbc60210..109f7558167aa 100644 --- a/drivers/usb/core/usb.c +++ b/drivers/usb/core/usb.c @@ -912,7 +912,7 @@ int usb_trylock_device(struct usb_device *udev) * is neither BINDING nor BOUND. Rather than sleeping to wait for the * lock, the routine polls repeatedly. This is to prevent deadlock with * disconnect; in some drivers (such as usb-storage) the disconnect() - * callback will block waiting for a device reset to complete. + * or suspend() method will block waiting for a device reset to complete. * * Returns a negative error code for failure, otherwise 1 or 0 to indicate * that the device will or will not have to be unlocked. (0 can be @@ -922,6 +922,8 @@ int usb_trylock_device(struct usb_device *udev) int usb_lock_device_for_reset(struct usb_device *udev, struct usb_interface *iface) { + unsigned long jiffies_expire = jiffies + HZ; + if (udev->state == USB_STATE_NOTATTACHED) return -ENODEV; if (udev->state == USB_STATE_SUSPENDED) @@ -938,6 +940,12 @@ int usb_lock_device_for_reset(struct usb_device *udev, } while (!usb_trylock_device(udev)) { + + /* If we can't acquire the lock after waiting one second, + * we're probably deadlocked */ + if (time_after(jiffies, jiffies_expire)) + return -EBUSY; + msleep(15); if (udev->state == USB_STATE_NOTATTACHED) return -ENODEV; |