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.

Sebastian Andrzej Siewior committed 5 years ago

Commit 09089db1 parent b4c6f862 files · +9 −2Browse files

Unified · Split

2 files

include/linux/irq_work.h +5 −0
kernel/irq_work.c +4 −2

include/linux/irq_work.h+5−0

@@ -49,6 +49,11 @@ static inline bool irq_work_is_busy(struct irq_work *work) · 48 unmodified lines
49	49	return atomic_read(&work->node.a_flags) & IRQ_WORK_BUSY;
50	50	}
51	51
	52	+static inline bool irq_work_is_hard(struct irq_work *work)
	53	+{
	54	+ return atomic_read(&work->node.a_flags) & IRQ_WORK_HARD_IRQ;
	55	+}
	56	+
52	57	bool irq_work_queue(struct irq_work *work);
53	58	bool irq_work_queue_on(struct irq_work *work, int cpu);
54	59

kernel/irq_work.c+4−2

@@ -217,7 +217,8 @@ void irq_work_single(void *arg) · 216 unmodified lines
217	217	*/
218	218	(void)atomic_cmpxchg(&work->node.a_flags, flags, flags & ~IRQ_WORK_BUSY);
219	219
220		− if (!arch_irq_work_has_interrupt())
	220	+ if ((IS_ENABLED(CONFIG_PREEMPT_RT) && !irq_work_is_hard(work)) \|\|
	221	+ !arch_irq_work_has_interrupt())
221	222	rcuwait_wake_up(&work->irqwait);
222	223	}
223	224
@@ -277,7 +278,8 @@ void irq_work_sync(struct irq_work *work) · 53 unmodified lines
277	278	lockdep_assert_irqs_enabled();
278	279	might_sleep();
279	280
280		− if (!arch_irq_work_has_interrupt()) {
	281	+ if ((IS_ENABLED(CONFIG_PREEMPT_RT) && !irq_work_is_hard(work)) \|\|
	282	+ !arch_irq_work_has_interrupt()) {
281	283	rcuwait_wait_event(&work->irqwait, !irq_work_is_busy(work),
282	284	TASK_UNINTERRUPTIBLE);
283	285	return;