Sure. First patch to linux in 16 years and all, I didn't want to be too noisy... Problem: If you use EVIOCGRAB, such as when you are using a Cr-48 with the Synaptics trackpad driver, the grab on the input device has to be dropped before you zero out the grab on the evdev, or you can't grab it again without rebooting. The X Server does this; it's usually not an issue for Chromium OS because it tends to just reboot, but everyone else gets a locked up pointer. I found this when copying the evdev_grab/input_device_grab() & input_release_device()/evdev_ungrab() design pattern into some new code to use for automated testing (record & playback of arbitrary event streams) and for training software for gesture recognition. When doing this sort of thing, you tend to repeat operations to obtain large training sets, or string together a series of test gestures with scripts, and the problem became obvious. This is pretty easy to reproduce with a modified evtest program that does an EVIOCGRAB, if you don't have a Synaptics touchpad to use for testing (but you won't get whatever you grab back unless you use the same fd or reboot). I have some patches to a number of bugs in the Synaptics driver, and some additional code cleanup vs. checkpatch.pl for drivers/input/evdev.c too, but I thought I'd start small. -- Terry On Thu, Feb 10, 2011 at 3:54 PM, Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote: > > On Thu, Feb 10, 2011 at 03:42:50PM -0800, tlambert@xxxxxxxxxxxx wrote: > > From: Terry Lambert <tlambert@xxxxxxxxxxxx> > > > > Fixed order of calls in evdev_ungrab to allow iterative use of > > code which grabs and releases input event devices. > > > > Sorry, could you please be more verbose? > > > Signed-off-by: Terry Lambert <tlambert@xxxxxxxxxxxx> > > --- > > drivers/input/evdev.c | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c > > index c8471a2..0bac8da 100644 > > --- a/drivers/input/evdev.c > > +++ b/drivers/input/evdev.c > > @@ -160,9 +160,9 @@ static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client) > > if (evdev->grab != client) > > return -EINVAL; > > > > + input_release_device(&evdev->handle); > > rcu_assign_pointer(evdev->grab, NULL); > > synchronize_rcu(); > > - input_release_device(&evdev->handle); > > > > return 0; > > } > > -- > > 1.7.3.1 > > > > -- > Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
