linux-kernel - Re: [PATCH 1/3] signal: sys_rt_sigtimedwait: simplify the timeout logic

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Date:	Mon, 25 Apr 2011 19:26:44 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Nikita V. Youshchenko" <nyoushchenko@...sta.com>,
	Matt Fleming <matt@...sole-pimps.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] signal: sys_rt_sigtimedwait: simplify the timeout
	logic

On 04/25, Tejun Heo wrote:
>
> On Sat, Apr 23, 2011 at 07:59:22PM +0200, Oleg Nesterov wrote:
> >
> > I don't understand why we are adding (ts.tv_sec || ts.tv_nsec) to
> > timespec_to_jiffies(&ts). Perhaps to ensure we will sleep at least
> > one jiffy if ts != 0? But in this case we should only check tv_nsec,
> > I don't think timespec_to_jiffies() can return zero if tv_sec != 0.
> > In fact I suspect timespec_to_jiffies() can only return zero if
> > tv_sec == tv_nsec == 0 because we add "TICK_NSEC - 1", but I am not
> > sure I understand correctly this math.
> >
> It might be a good idea to note the weird jiffies calculation with a
> comment?

If only I knew what this comment could say except

	/* Why do we add (tv_sec || tv_nsec) ?  */

I'd better send 4/3 which simply removes this (I hope) unneeded code.

Oleg.

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