Hi Anshul,
On Sun, Jan 04, 2015 at 12:25:55AM -0800, Anshul Garg wrote:
> From: Anshul Garg <aksgarg1989@xxxxxxxxx>
>
> If input device is grabbed then client which has grabbed the device can
> flush or write to the device so for other clients -EINVAL should be returned.
>
> Signed-off-by: Anshul Garg <anshul.g@xxxxxxxxxxx>
> ---
> drivers/input/evdev.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
> index b1a52ab..105e489 100644
> --- a/drivers/input/evdev.c
> +++ b/drivers/input/evdev.c
> @@ -277,6 +277,8 @@ static int evdev_flush(struct file *file, fl_owner_t id)
>
> if (!evdev->exist || client->revoked)
> retval = -ENODEV;
> + else if (evdev->grab && evdev->grab != client)
> + retval = -EINVAL;
> else
> retval = input_flush_device(&evdev->handle, file);
>
> @@ -475,6 +477,11 @@ static ssize_t evdev_write(struct file *file, const char __user *buffer,
> goto out;
> }
>
> +
> + if (evdev->grab && evdev->grab != client) {
> + retval = -EINVAL;
> + goto out;
> + }
Grab is supposed to be transparent to the other users, so returning
error here is not desirable. Also, input_inject_event() will already
ignore events if device is grabbed, so everything is good as far as
evdev_write() concerned.
Flush is a bit trickier: the driver should only "flush" data that
belongs to the user that issued flush request (and the owner is
identified by file handle passed to flush() method). I think it is OK to
allow owner to flush its own data even while device is grabbed.
Thanks.
--
Dmitry
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