Commit 09089db7 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Peter Zijlstra
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irq_work: Also rcuwait for !IRQ_WORK_HARD_IRQ on PREEMPT_RT 



On PREEMPT_RT most items are processed as LAZY via softirq context.
Avoid to spin-wait for them because irq_work_sync() could have higher
priority and not allow the irq-work to be completed.

Wait additionally for !IRQ_WORK_HARD_IRQ irq_work items on PREEMPT_RT.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20211006111852.1514359-5-bigeasy@linutronix.de
parent b4c6f86e

include/linux/irq_work.h

+5 −0
Original line number Diff line number Diff line
@@ -49,6 +49,11 @@ static inline bool irq_work_is_busy(struct irq_work *work) 
	return atomic_read(&work->node.a_flags) & IRQ_WORK_BUSY;

}



static inline bool irq_work_is_hard(struct irq_work *work)

{

	return atomic_read(&work->node.a_flags) & IRQ_WORK_HARD_IRQ;

}



bool irq_work_queue(struct irq_work *work);

bool irq_work_queue_on(struct irq_work *work, int cpu);

kernel/irq_work.c

+4 −2
Original line number Diff line number Diff line
@@ -217,7 +217,8 @@ void irq_work_single(void *arg) 
	 */

	(void)atomic_cmpxchg(&work->node.a_flags, flags, flags & ~IRQ_WORK_BUSY);



	if (!arch_irq_work_has_interrupt())

	if ((IS_ENABLED(CONFIG_PREEMPT_RT) && !irq_work_is_hard(work)) ||

	    !arch_irq_work_has_interrupt())

		rcuwait_wake_up(&work->irqwait);

}
@@ -277,7 +278,8 @@ void irq_work_sync(struct irq_work *work) 
	lockdep_assert_irqs_enabled();

	might_sleep();



	if (!arch_irq_work_has_interrupt()) {

	if ((IS_ENABLED(CONFIG_PREEMPT_RT) && !irq_work_is_hard(work)) ||

	    !arch_irq_work_has_interrupt()) {

		rcuwait_wait_event(&work->irqwait, !irq_work_is_busy(work),

				   TASK_UNINTERRUPTIBLE);

		return;