linux-kernel - Re: input.c: start on release

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Message-Id: <20070223164424.0454e11e.zaitcev@redhat.com>
Date:	Fri, 23 Feb 2007 16:44:24 -0800
From:	Pete Zaitcev <zaitcev@...hat.com>
To:	"Dmitry Torokhov" <dmitry.torokhov@...il.com>
Cc:	linux-kernel@...r.kernel.org, zaitcev@...hat.com
Subject: Re: input.c: start on release

On Fri, 23 Feb 2007 10:06:14 -0500, "Dmitry Torokhov" <dmitry.torokhov@...il.com> wrote:
> On 2/23/07, Pete Zaitcev <zaitcev@...hat.com> wrote:

> > void input_release_device(struct input_handle *handle)
> > {
> > ....
> >        if (handle->handler->start)
> >                handle->handler->start(handle);

> It should be ->start(). You are probably confused a little by the name
> of the function. input_release_device() is called when userspace
> issues ioctl(fd, EVIOCGRAB, 0) releasing (or ungrabbing) the device
> (as opposed to xxx_release(file, inode) type functions that are called
> when last user of a file drops off). In our case we want to give
> handlers a chance to resume their control over device. Right now
> standard keyboard driver uses start method do bring back in sync LED
> state of a keyborad-like device after it was released (ungrabbed).

Thanks for the explanation. I suspect people asked you 100 times before.
I can see why we would want to do this when a grab ends, but why do
we do this on every close of /dev/input/mice? The call path is:

 mousedev_release ->
 mixdev_release (optional for some majors)
 input_close_device ->
 input_release_device

Same thing happens upon disconnect, though this is probably harmless,
as the device is gone already anyway.

To tell you the truth, all I really want is to hold a static mutex
across a call to input_close_device(). Can I do that?

-- Pete
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