From mboxrd@z Thu Jan  1 00:00:00 1970
Subject: Re: [Fwd: [Adeos-main] LRTBF par-log.c & adeos_critical_enter
	question]
From: Kristian Benoit <kbenoit@domain.hid>
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Date: Mon, 11 Jul 2005 17:28:58 -0400
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To: Hannes Mayer <h.mayer@domain.hid>
Cc: adeos-main@gna.org, Philippe Gerum <rpm@xenomai.org>

On Mon, 2005-07-11 at 20:00 +0200, Hannes Mayer wrote:
> Dear Kristian!
> 
> Philippe (Gerum) just notified me, that you're probably not subscribed
> to the Adeos-Main maillist, so I'm forwarding my mail to the list.
> I hope that is OK.

Now I am :) thanks.

> After adeos_critical_enter, interrupts are disabled anyway (right?), so no
> modification of read_pos or write_pos is possible and reading over the
> proc file is not disturbed.
> 
> Furthermore in read_proc you reset disable_timer only after the complete
> buffer was read via the proc file:
> 
> 	if (read_pos == write_pos) {
> 		disable_timer = 0;

Exactly, that's the reason.

> The problem:
> While some user-space app is reading from the proc file, nothing is written
> to the buffer and this causes data loss.

As it actually is only used by lrtbf in the way I wrote it, it does not
really matters. And in that particular case it is better like that as I
insert the module. Do some job on the target. Then when the job is done,
I start reading from the proc file and dont get post job interrupt data
in the buffer.

> IMO, it would be best, if writing to the buffer is not disabled in read_proc.
> In the actual data copying action in read_proc/while-loop no interrupt can
> interfer - and if not everything from the buffer was read in the first place,
> there is no problem if some data is added to the buffer until the next read
> action occurs.

I must admit that it is not really made to be read more than once. I
thought of doiing a double buffering method, but I did'nt much time to
implement an unnecessary feature. (unnecessary in the actual state)   

Kristian