On 20/12/15 20:52, Daniel Thompson wrote:
> It is currently possible for FIQ handlers to re-enter gic_raise_softirq()
> and lock up.
>
> gic_raise_softirq()
> lock(x);
> -~-> FIQ
> handle_fiq()
> gic_raise_softirq()
> lock(x); <-- Lockup
>
> arch/arm/ uses IPIs to implement arch_irq_work_raise(), thus this issue
> renders it difficult for FIQ handlers to safely defer work to less
> restrictive calling contexts.
>
> This patch fixes the problem by converting the cpu_map_migration_lock
> into a rwlock making it safe to re-enter the function.
>
> Note that having made it safe to re-enter gic_raise_softirq() we no
> longer need to mask interrupts during gic_raise_softirq() because the
> b.L migration is always performed from task context.
>
> Signed-off-by: Daniel Thompson <daniel.thomp...@linaro.org>
> Cc: Thomas Gleixner <t...@linutronix.de>
> Cc: Jason Cooper <ja...@lakedaemon.net>
> Cc: Russell King <li...@arm.linux.org.uk>
> Cc: Marc Zyngier <marc.zyng...@arm.com>
> Acked-by: Nicolas Pitre <nicolas.pi...@linaro.org>
Acked-by: Marc Zyngier <marc.zyng...@arm.com>
M.
--
Jazz is not dead. It just smells funny...
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