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From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/6] sched, wait: Collapse __wait_event macros -v4
Date: Tue, 1 Oct 2013 17:16:38 +0200	[thread overview]
Message-ID: <20131001151638.GA2246@redhat.com> (raw)
In-Reply-To: <20131001143921.GO3657@laptop.programming.kicks-ass.net>

On 10/01, Peter Zijlstra wrote:
>
> On Tue, Oct 01, 2013 at 04:09:40PM +0200, Oleg Nesterov wrote:
> > But somehow I didn't realize that ___wait_cond_timeout() can be used
> > as is, so the simple patch below should work?
>
> Yeah, should work.. But how often do people use timeout=0?

I do not know. Perhaps never.

> Should we
> really care about that case to the effect of adding more code.

Again, I do not really know. But imo it would be better to fix
this anyway, even if the problem is really minor. If nothing
else, wait_event_timeout() and __wait_event_timeout() should have
the same semantics.

And suppose that we ha a helper(timeout) which calls wait_event_timeout(),
and checks the non-trivial condition inside. Now suppose that someone
does

	timeout = DEFAULT_TIMEOUT;

	if (option_nonblock)
		timeout = 0;

	ok = helper(timeout);

So do you think we should ignore this or I should send 7/6 with the
changelog ?

(In fact I am going to send another patch on top of this series later.
 At least, try to send for discussion because I know you dislike the
 idea to move the signal-pending checks out of line).

Oleg.


  reply	other threads:[~2013-10-01 15:23 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-30 15:22 [PATCH 0/6] sched, wait: Collapse __wait_event macros -v4 Peter Zijlstra
2013-09-30 15:22 ` [PATCH 1/6] sched, wait: Make the signal_pending() checks consistent Peter Zijlstra
2013-09-30 15:22 ` [PATCH 2/6] sched, wait: Change timeout logic Peter Zijlstra
2013-09-30 15:48   ` Linus Torvalds
2013-09-30 16:09     ` Peter Zijlstra
2013-09-30 15:22 ` [PATCH 3/6] sched, wait: Change the wait_exclusive control flow Peter Zijlstra
2013-09-30 15:22 ` [PATCH 4/6] sched, wait: Collapse __wait_event macros Peter Zijlstra
2013-09-30 15:22 ` [PATCH 5/6] sched, wait: Also use ___wait_event() for __wait_event_hrtimeout Peter Zijlstra
2013-09-30 15:22 ` [PATCH 6/6] sched, wait: Make the __wait_event*() interface more friendly Peter Zijlstra
2013-10-01  6:39   ` Ingo Molnar
2013-09-30 15:50 ` [PATCH 0/6] sched, wait: Collapse __wait_event macros -v4 Linus Torvalds
2013-09-30 16:11   ` Peter Zijlstra
2013-09-30 17:40 ` Oleg Nesterov
2013-09-30 18:00   ` Oleg Nesterov
2013-09-30 18:09   ` Peter Zijlstra
2013-09-30 18:13     ` Oleg Nesterov
2013-10-01 14:09       ` Oleg Nesterov
2013-10-01 14:39         ` Peter Zijlstra
2013-10-01 15:16           ` Oleg Nesterov [this message]
2013-10-01 17:01 ` [RFC] introduce prepare_to_wait_event() Oleg Nesterov
2013-10-01 17:25   ` Peter Zijlstra
2013-10-01 17:33     ` Oleg Nesterov
2013-10-01 17:44       ` Peter Zijlstra

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