Messages in this thread | | | From | "Henrik Rydberg" <> | Date | Fri, 11 Feb 2011 11:04:39 +0100 | Subject | Re: [PATCH] Input: fixed EVIOCGRAB iterative grab/release. |
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Hi Terry,
> Fixed order of calls in evdev_ungrab to allow iterative use of > code which grabs and releases input event devices. > > Signed-off-by: Terry Lambert <tlambert@chromium.org> > --- > 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);
I imagine the current code could lead to a race situation if there were no other locks involved. However, evdev_ungrab() is always called under evdev->mutex. As Dmitry hinted, grabbing "usually works", so perhaps you could device a tiny program which reproduces the problem?
Thanks, Henrik
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