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

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Message-ID: <20110425113746.GM17734@mtj.dyndns.org>
Date:	Mon, 25 Apr 2011 13:37:46 +0200
From:	Tejun Heo <tj@...nel.org>
To:	Oleg Nesterov <oleg@...hat.com>
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 Sat, Apr 23, 2011 at 07:59:22PM +0200, Oleg Nesterov wrote:
> No functional changes, cleanup compat_sys_rt_sigtimedwait() and
> sys_rt_sigtimedwait().
> 
> Calculate the timeout before we take ->siglock, this simplifies and
> lessens the code. Use timespec_valid() to check the timespec.
> 
> 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.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

Acked-by: Tejun Heo <tj@...nel.org>

It might be a good idea to note the weird jiffies calculation with a
comment?

Thanks.

-- 
tejun
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