linux-kernel - Re: [PATCH v2 01/12] sched: Simplify INIT_PREEMPT

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Date:	Thu, 1 Oct 2015 15:25:46 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	mingo@...nel.org, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, oleg@...hat.com,
	umgwanakikbuti@...il.com, tglx@...utronix.de, rostedt@...dmis.org
Subject: Re: [PATCH v2 01/12] sched: Simplify INIT_PREEMPT_COUNT

On Wed, Sep 30, 2015 at 09:10:36AM +0200, Peter Zijlstra wrote:
> As per commit d86ee4809d03 ("sched: optimize cond_resched()") we need
> PREEMPT_ACTIVE to avoid cond_resched() from working before the
> scheduler is setup.
> 
> However, keeping preemption disabled should do the same thing already,
> making the PREEMPT_ACTIVE part entirely redundant.
> 
> The only complication is !PREEMPT_COUNT kernels, where
> PREEMPT_DISABLED ends up being 0. Instead we use an unconditional
> PREEMPT_OFFSET to set preempt_count() even on !PREEMPT_COUNT kernels.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

Reviewed-by: Frederic Weisbecker <fweisbec@...il.com>

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