linux-kernel - Re: [PATCH 3.18-rc3 v8 1/4] irqchip: gic: Make gic_raise

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Date:	Mon, 24 Nov 2014 21:09:01 +0000
From:	Daniel Thompson <daniel.thompson@...aro.org>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	Jason Cooper <jason@...edaemon.net>,
	Russell King <linux@....linux.org.uk>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	patches@...aro.org, linaro-kernel@...ts.linaro.org,
	John Stultz <john.stultz@...aro.org>,
	Sumit Semwal <sumit.semwal@...aro.org>,
	Dirk Behme <dirk.behme@...bosch.com>,
	Daniel Drake <drake@...lessm.com>,
	Dmitry Pervushin <dpervushin@...il.com>,
	Marc Zyngier <marc.zyngier@....com>
Subject: Re: [PATCH 3.18-rc3 v8 1/4] irqchip: gic: Make gic_raise_softirq()
 FIQ-safe

On 24/11/14 20:41, Thomas Gleixner wrote:
> On Mon, 24 Nov 2014, Daniel Thompson wrote:
>> I did want to remove the lock too. However when I reviewed this code I
>> concluded the lock was still required. Without it I think it is possible
>> for gic_raise_softirq() to raise an IPI on the old core *after* the code
>> to migrate pending IPIs has been run.
> 
> And I bet it took you quite some time to figure that out from that
> overly documented abuse of irq_controller_lock. See my other reply.

Yes. It did take quite some time, although compared to some of the other
FIQ/NMI-safety reviews I've been doing recently it could be worse. ;-)

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