From mboxrd@z Thu Jan  1 00:00:00 1970
From: james.morse@arm.com (James Morse)
Date: Fri, 04 Dec 2015 11:00:19 +0000
Subject: [PATCH v7 3/3] arm64: Add do_softirq_own_stack() and enable
 irq_stacks
In-Reply-To: <20151127114715.GA25499@e104818-lin.cambridge.arm.com>
References: <1447698128-8490-1-git-send-email-james.morse@arm.com>
 <1447698128-8490-4-git-send-email-james.morse@arm.com>
 <8F6484A9-18B9-4A81-B58D-528D81BC196D@gmail.com>
 <20151127114715.GA25499@e104818-lin.cambridge.arm.com>
Message-ID: <56617243.5050602@arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 27/11/15 11:47, Catalin Marinas wrote:
> With this approach, we could run softirq either on the IRQ stack or on
> the process stack. One such process is softirqd, so there shouldn't be a
> problem since its goal is to run softirqs. But do_softirq() may be
> invoked from other contexts (network stack), I'm not sure what the stack
> looks like at that point.

As long as we don't reduce the stack sizes yet - nothing has changed. We
already run __do_softirq() on other task's stacks via __irq_exit().


> We could just do like x86 and always switch to the IRQ stack before
> invoking __do_softirq(). I don't think we lose much.

I will add an extra patch to do this - its not as straight forward as I
would like - as both ksoftirqd and softirq on irq_stack call
do_softirq_own_stack() with irq_count == 0.


Thanks,

James