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.thompson@linaro.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Jason Cooper jason@lakedaemon.net Cc: Russell King linux@arm.linux.org.uk Cc: Marc Zyngier marc.zyngier@arm.com Acked-by: Nicolas Pitre nicolas.pitre@linaro.org
Acked-by: Marc Zyngier marc.zyngier@arm.com
M.