linux-kernel - Re: Debugging Thinkpad T430s occasional suspend failure.

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Message-ID: <CA+55aFz4vO-JGv+A7h=uxwfyWEMcK=Q3gntwHfr=a4OUVs-f+g@mail.gmail.com>
Date:	Sun, 17 Feb 2013 09:32:15 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Dave Jones <davej@...hat.com>, Hugh Dickins <hughd@...gle.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Paul McKenney <paul.mckenney@...aro.org>
Subject: Re: Debugging Thinkpad T430s occasional suspend failure.

On Sun, Feb 17, 2013 at 7:11 AM, Frederic Weisbecker <fweisbec@...il.com> wrote:
>
> preempt_value_in_interrupt() looks buggy in your patch: it makes
> invoke_softirq() returning if (val & HARDIRQ_MASK). But that's always
> true since you have moved further the sub_preempt_count(IRQ_EXIT)
> further.

No, that's not it. The value hasn't been written back yet, but it already did:

+       int offset = IRQ_EXIT_OFFSET;
+       int count = preempt_count() - offset;

so the 'count' has the IRQ_EXIT_OFFSET already subtracted. So no,
HARDIRQ_MASK is *not* always set.

                   Linus
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