Re: Two questions regarding evdev

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi David,

On Wednesday 24 March 2010 01:53:32 pm David Härdeman wrote:
> I've been going over the evdev (drivers/input/evdev.c) code since I'm
> using it as inspiration for a small project I'm hacking on. So far I
> have two questions with regard to the code:
> 
> First, evdev_event passes a new event to all connected clients (writing
> it to each client's event fifo) and then calls wake_up_interruptible.
> However, given that all clients will have at least one new event to read
> after evdev_event is done, shouldn't wake_up_interruptible_all be called
> instead?

wake_up() vs. wake_up_all() only matters if there is exclusive waiters
which evdev does not use. PLease see comment/explanation for wake up
here:

	http://lxr.linux.no/linux+v2.6.33/kernel/sched.c#L5685

> 
> Second, evdev_poll never sets the POLLOUT flag, but evdev can accept
> writes (which will be passed to input_inject_event), so shouldn't the
> POLLOUT flag always be set?

We could but I guess nobody tries to pull evdev for writing, everyone
is interested in reading. 

-- 
Dmitry
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