Re: [PATCH v2 01/26] genirq: add irq_domain-aware core IRQ handler

Stephen Boyd
2014-08-26T17:42:44Z

On 08/26/14 03:03, Marc Zyngier wrote:
> Calling irq_find_mapping from outside a irq_{enter,exit} section is
> unsafe and produces ugly messages if CONFIG_PROVE_RCU is enabled:
> If coming from the idle state, the rcu_read_lock call in irq_find_mapping
> will generate an unpleasant warning:
>
> <quote>
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.16.0-rc1+ #135 Not tainted
> -------------------------------
> include/linux/rcupdate.h:871 rcu_read_lock() used illegally while idle!
>
> other info that might help us debug this:
>
> RCU used illegally from idle CPU!
> rcu_scheduler_active = 1, debug_locks = 0
> RCU used illegally from extended quiescent state!
> 1 lock held by swapper/0/0:
> #0: (rcu_read_lock){......}, at: [<ffffffc00010206c>]
> irq_find_mapping+0x4c/0x198

Do you have the whole stacktrace? I don't see where this is called
outside of irq_enter() from within the idle loop, but maybe I missed
something.

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