Re: [PATCH v2 00/26] genirq: fix use of irq_find_mapping outside of legal RCU context

Marc Zyngier
2014-09-03T12:21:07Z

[Dropping linux@openrisc.net from the CC list]

On 03/09/14 13:09, Thomas Gleixner wrote:
> On Wed, 3 Sep 2014, Jason Cooper wrote:
>
>> On Wed, Aug 27, 2014 at 10:33:44AM +0100, Marc Zyngier wrote:
>>> Hi Thomas,
>>>
>>> On Tue, Aug 26 2014 at 10:34:51 pm BST, Thomas Gleixner <tglx@linutronix.de> wrote:
>>>> On Tue, 26 Aug 2014, Marc Zyngier wrote:
>>>>
>>>>> A number of irqchip drivers are directly calling irq_find_mapping,
>>>>> which may use a rcu_read_lock call when walking the radix tree.
>>>>>
>>>>> Turns out that if you hit that point with CONFIG_PROVE_RCU enabled,
>>>>> the kernel will shout at you, as using RCU in this context may be
>>>>> illegal (specially if coming from the idle state, where RCU would be
>>>>> in a quiescent state).
>>>>>
>>>>> A possible fix would be to wrap calls to irq_find_mapping into a
>>>>> RCU_NONIDLE macro, but that really looks ugly.
>>>>>
>>>>> This patch series introduce another generic IRQ entry point
>>>>> (handle_domain_irq), which has the exact same behaviour as handle_IRQ
>>>>> (as defined on arm, arm64 and openrisc), except that it also takes a
>>>>> irq_domain pointer. This allows the logical IRQ lookup to be done
>>>>> inside the irq_{enter,exit} section, which contains a
>>>>> rcu_irq_{enter,exit}, making it safe.
>>>>
>>>> Looks good. Should this be routed to the genirq tree?
>>>
>>> I'm happy for you to take this series, provided the architecture
>>> maintainers agree on it (I'm still to hear from the openrisc guys, and
>>> their mailing-list seems to positively hate my guts).
>>
>> I think everyone's had a chance to look over it by now. Thomas, shall I
>> take the series?
>
> Yes please.

Do you want a pull request? Or are you picking up the patches from the ML?

Thanks,

M.
--
Jazz is not dead. It just smells funny...