Re: [PATCH v2 1/6] hid: new driver for PicoLCD device

[Dmitry Torokhov]

On Sun, Mar 21, 2010 at 05:37:37PM +0100, Bruno Prémont wrote:
> On Sat, 20 March 2010 Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote:
> > > +	usbhid_submit_report(data->hdev, report, USB_DIR_OUT);
> > > +	complete_all(&data->ready);
> > > +	INIT_COMPLETION(data->ready);
> > 
> > Umm, what does this do, exactly?
> 
> It wakes up anyone waiting on the completion and then resets the completion
> as otherwise any future attempt to wait on it would succeed immediately.
> 

You realize that if you re-initialize the completion right after
signalling it there is a big chance the waiters will miss it (they do
check completion->done flags that you reset right away.

In general completions are suited for something that happens once (a
single request - allocated - processed - signalled) but not for
repeating use.

Thanks.

-- 
Dmitry
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