From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [PATCH 3/5] irq_work: Allow irq_work_sync() to sleep if irq_work() no IRQ support.
Date: Mon, 27 Sep 2021 23:19:17 +0200 [thread overview]
Message-ID: <20210927211919.310855-4-bigeasy@linutronix.de> (raw)
In-Reply-To: <20210927211919.310855-1-bigeasy@linutronix.de>
irq_work() triggers instantly an interrupt if supported by the
architecture. Otherwise the work will be processed on the next timer
tick. In worst case irq_work_sync() could spin up to a jiffy.
irq_work_sync() is usually used in tear down context which is fully
preemptible. Based on review irq_work_sync() is invoked from preemptible
context and there is one waiter at a time. This qualifies it to use
rcuwait for synchronisation.
Let irq_work_sync() synchronize with rcuwait if the architecture
processes irqwork via the timer tick.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/irq_work.h | 3 +++
kernel/irq_work.c | 10 ++++++++++
2 files changed, 13 insertions(+)
diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h
index ec2a47a81e423..b48955e9c920e 100644
--- a/include/linux/irq_work.h
+++ b/include/linux/irq_work.h
@@ -3,6 +3,7 @@
#define _LINUX_IRQ_WORK_H
#include <linux/smp_types.h>
+#include <linux/rcuwait.h>
/*
* An entry can be in one of four states:
@@ -16,11 +17,13 @@
struct irq_work {
struct __call_single_node node;
void (*func)(struct irq_work *);
+ struct rcuwait irqwait;
};
#define __IRQ_WORK_INIT(_func, _flags) (struct irq_work){ \
.node = { .u_flags = (_flags), }, \
.func = (_func), \
+ .irqwait = __RCUWAIT_INITIALIZER(irqwait), \
}
#define IRQ_WORK_INIT(_func) __IRQ_WORK_INIT(_func, 0)
diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index caf2edffa20d5..853af2cee3612 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -160,6 +160,9 @@ void irq_work_single(void *arg)
* else claimed it meanwhile.
*/
(void)atomic_cmpxchg(&work->node.a_flags, flags, flags & ~IRQ_WORK_BUSY);
+
+ if (!arch_irq_work_has_interrupt())
+ rcuwait_wake_up(&work->irqwait);
}
static void irq_work_run_list(struct llist_head *list)
@@ -204,6 +207,13 @@ void irq_work_tick(void)
void irq_work_sync(struct irq_work *work)
{
lockdep_assert_irqs_enabled();
+ might_sleep();
+
+ if (!arch_irq_work_has_interrupt()) {
+ rcuwait_wait_event(&work->irqwait, !irq_work_is_busy(work),
+ TASK_UNINTERRUPTIBLE);
+ return;
+ }
while (irq_work_is_busy(work))
cpu_relax();
--
2.33.0
next prev parent reply other threads:[~2021-09-27 21:19 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-27 21:19 [PATCH 0/5] irq_work: PREEMPT_RT bits Sebastian Andrzej Siewior
2021-09-27 21:19 ` [PATCH 1/5] sched/rt: Annotate the RT balancing logic irqwork as IRQ_WORK_HARD_IRQ Sebastian Andrzej Siewior
2021-09-27 21:19 ` [PATCH 2/5] irq_work: Ensure that irq_work runs in in-IRQ context Sebastian Andrzej Siewior
2021-10-05 15:48 ` Sebastian Andrzej Siewior
2021-10-05 20:11 ` Peter Zijlstra
2021-09-27 21:19 ` Sebastian Andrzej Siewior [this message]
2021-09-27 21:19 ` [PATCH 4/5] irq_work: Handle some irq_work in SOFTIRQ on PREEMPT_RT Sebastian Andrzej Siewior
2021-09-30 9:07 ` Peter Zijlstra
2021-09-30 9:53 ` Sebastian Andrzej Siewior
2021-09-30 14:39 ` Peter Zijlstra
2021-09-30 16:38 ` Sebastian Andrzej Siewior
2021-10-01 10:32 ` Peter Zijlstra
2021-10-01 12:08 ` Sebastian Andrzej Siewior
2021-10-01 13:40 ` Peter Zijlstra
2021-09-27 21:19 ` [PATCH 5/5] irq_work: Also rcuwait for !IRQ_WORK_HARD_IRQ " Sebastian Andrzej Siewior
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