linux-kernel - Re: [PATCH] sched: idle: move need_resched check after function rcu_idle

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Message-ID: <20151123175754.GL17308@twins.programming.kicks-ass.net>
Date:	Mon, 23 Nov 2015 18:57:54 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Lianwei Wang <lianwei.wang@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-pm@...ts.linux-foundation.org,
	rjw@...ysocki.net, mingo@...hat.com
Subject: Re: [PATCH] sched: idle: move need_resched check after function
 rcu_idle_enter

On Mon, Nov 23, 2015 at 09:42:06AM -0800, Lianwei Wang wrote:
> Issue was found on ARM/Qcom platform, but I think it is applicable to
> other platforms as well.  I add a BUG_ON after rcu_enter_idle to catch
> it. The Qcom's cpuidle driver is not in mainline kernel yet.


A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?


And I suspect that your qualcom thing doesn't have TIF_POLLING_NRFLAG
either, which would introduce another need_resched() test after the
rcu_enter_idle() call.
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