genirq: Always force thread affinity (04aa530e) · Commits · 戴 / test

Sankara reported that the genirq core code fails to adjust the affinity of an interrupt thread in several cases: 1) On request/setup_irq() the call to setup_affinity() happens before the new action is registered, so the new thread is not notified. 2) For secondary shared interrupts nothing notifies the new thread to change its affinity. 3) Interrupts which have the IRQ_NO_BALANCE flag set are not moving the thread either. Fix this by setting the thread affinity flag right on thread creation time. This ensures that under all circumstances the thread moves to the right place. Requires a check in irq_thread_check_affinity for an existing affinity mask (CONFIG_CPU_MASK_OFFSTACK=y) Reported-and-tested-by:

Sankara Muthukrishnan <sankara.m@gmail.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1209041738200.2754@ionos Signed-off-by:

Thomas Gleixner <tglx@linutronix.de>

kernel/irq/manage.c

+21 −2

Original line number	Diff line number	Diff line
		@@ -732,6 +732,7 @@ static void
		irq_thread_check_affinity(struct irq_desc desc, struct irqaction action)
		{
		cpumask_var_t mask;
		bool valid = true;

		if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
		return;
		@@ -746,9 +747,17 @@ irq_thread_check_affinity(struct irq_desc desc, struct irqaction action)
		}

		raw_spin_lock_irq(&desc->lock);
		/*
		* This code is triggered unconditionally. Check the affinity
		* mask pointer. For CPU_MASK_OFFSTACK=n this is optimized out.
		*/
		if (desc->irq_data.affinity)
		cpumask_copy(mask, desc->irq_data.affinity);
		else
		valid = false;
		raw_spin_unlock_irq(&desc->lock);

		if (valid)
		set_cpus_allowed_ptr(current, mask);
		free_cpumask_var(mask);
		}
		@@ -954,6 +963,16 @@ __setup_irq(unsigned int irq, struct irq_desc desc, struct irqaction new)
		*/
		get_task_struct(t);
		new->thread = t;
		/*
		* Tell the thread to set its affinity. This is
		* important for shared interrupt handlers as we do
		* not invoke setup_affinity() for the secondary
		* handlers as everything is already set up. Even for
		* interrupts marked with IRQF_NO_BALANCE this is
		* correct as we want the thread to move to the cpu(s)
		* on which the requesting code placed the interrupt.
		*/
		set_bit(IRQTF_AFFINITY, &new->thread_flags);
		}

		if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {

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