linux-kernel - Re: [PATCH] evdev: Release eventual input device grabs when getting disconnected

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Date:	Mon, 31 Mar 2008 23:02:46 +0200
From:	Johannes Berg <johannes@...solutions.net>
To:	Björn Steinbrink <B.Steinbrink@....de>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jiri Kosina <jkosina@...e.cz>
Subject: Re: [PATCH] evdev: Release eventual input device grabs when
	getting disconnected


> --- a/drivers/input/evdev.c
> +++ b/drivers/input/evdev.c
> @@ -853,6 +853,9 @@ static void evdev_cleanup(struct evdev *evdev)
>  	evdev_hangup(evdev);
>  	evdev_remove_chrdev(evdev);
>  
> +	if (evdev->grab)
> +		evdev_ungrab(evdev, evdev->grab);
> +

You might want to insert a comment about why this is safe and doesn't
race since it's not entirely trivial to see because everything else that
manipulates the grab needs to take the mutex. In fact, I'm not entirely
sure it's race-free but at least it can't race against the ioctl handler
because by this time ->exist will be 0.

johannes

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