Messages in this thread Patch in this message | | | Date | Fri, 15 Oct 2021 09:44:54 -0000 | From | "tip-bot2 for Sebastian Andrzej Siewior" <> | Subject | [tip: sched/core] irq_work: Also rcuwait for !IRQ_WORK_HARD_IRQ on PREEMPT_RT |
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The following commit has been merged into the sched/core branch of tip:
Commit-ID: 09089db79859cbccccd8df95b034f36f7027efa6 Gitweb: https://git.kernel.org/tip/09089db79859cbccccd8df95b034f36f7027efa6 Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> AuthorDate: Wed, 06 Oct 2021 13:18:52 +02:00 Committer: Peter Zijlstra <peterz@infradead.org> CommitterDate: Fri, 15 Oct 2021 11:25:18 +02:00
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: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20211006111852.1514359-5-bigeasy@linutronix.de --- include/linux/irq_work.h | 5 +++++ kernel/irq_work.c | 6 ++++-- 2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h index b48955e..8cd11a2 100644 --- a/include/linux/irq_work.h +++ b/include/linux/irq_work.h @@ -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); diff --git a/kernel/irq_work.c b/kernel/irq_work.c index 90b6b56..f7df715 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -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;
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