linux-kernel - do_schedule_next_timer && si_overrun (Was: [PATCH] posix-timers: Do not modify an already queued timer signal)

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Message-ID: <20080721154006.GB182@tv-sign.ru>
Date:	Mon, 21 Jul 2008 19:40:06 +0400
From:	Oleg Nesterov <oleg@...sign.ru>
To:	Roland McGrath <roland@...hat.com>
Cc:	Mark McLoughlin <markmc@...hat.com>, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: do_schedule_next_timer && si_overrun (Was: [PATCH] posix-timers: Do not modify an already queued timer signal)

On 07/21, Oleg Nesterov wrote:
>
> On 07/20, Roland McGrath wrote:
> >
> > You do need to clear si_overrun there to be correct in the usual case
> > (not already queued).
>
> Indeed, I missed that. Can't we do this in send_sigqueue() ?

The more I look at the code, the more I'm getting confused...

Suppose that posix_timer_event()->send_sigqueue() increments info.si_overrun.
But (in general) it is not reported to the user-space, do_schedule_next_timer()
does:

	info->si_overrun = timr->it_overrun_last;

shouldn't it do

	info->si_overrun += timr->it_overrun_last;

instead?

Oleg.

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