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authorSebastian Andrzej Siewior <bigeasy@linutronix.de>2024-07-04 19:03:41 +0200
committerPeter Zijlstra <peterz@infradead.org>2024-07-09 13:26:37 +0200
commit2b84def990d388bed4afe4f21ae383a01991046c (patch)
tree91218c98aa370156832d528b67700c4636f1ee6b /kernel/events
parent16b9569df9d2ab07eeee075cb7895e9d3e08e8f0 (diff)
perf: Split __perf_pending_irq() out of perf_pending_irq()
perf_pending_irq() invokes perf_event_wakeup() and __perf_pending_irq(). The former is in charge of waking any tasks which waits to be woken up while the latter disables perf-events. The irq_work perf_pending_irq(), while this an irq_work, the callback is invoked in thread context on PREEMPT_RT. This is needed because all the waking functions (wake_up_all(), kill_fasync()) acquire sleep locks which must not be used with disabled interrupts. Disabling events, as done by __perf_pending_irq(), expects a hardirq context and disabled interrupts. This requirement is not fulfilled on PREEMPT_RT. Split functionality based on perf_event::pending_disable into irq_work named `pending_disable_irq' and invoke it in hardirq context on PREEMPT_RT. Rename the split out callback to perf_pending_disable(). Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Marco Elver <elver@google.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Link: https://lore.kernel.org/r/20240704170424.1466941-8-bigeasy@linutronix.de
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/core.c29
1 files changed, 22 insertions, 7 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 96e03d6b52d1..f64c30e7d5da 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2451,7 +2451,7 @@ static void __perf_event_disable(struct perf_event *event,
* hold the top-level event's child_mutex, so any descendant that
* goes to exit will block in perf_event_exit_event().
*
- * When called from perf_pending_irq it's OK because event->ctx
+ * When called from perf_pending_disable it's OK because event->ctx
* is the current context on this CPU and preemption is disabled,
* hence we can't get into perf_event_task_sched_out for this context.
*/
@@ -2491,7 +2491,7 @@ EXPORT_SYMBOL_GPL(perf_event_disable);
void perf_event_disable_inatomic(struct perf_event *event)
{
event->pending_disable = 1;
- irq_work_queue(&event->pending_irq);
+ irq_work_queue(&event->pending_disable_irq);
}
#define MAX_INTERRUPTS (~0ULL)
@@ -5218,6 +5218,7 @@ static void perf_pending_task_sync(struct perf_event *event)
static void _free_event(struct perf_event *event)
{
irq_work_sync(&event->pending_irq);
+ irq_work_sync(&event->pending_disable_irq);
perf_pending_task_sync(event);
unaccount_event(event);
@@ -6749,7 +6750,7 @@ static void perf_sigtrap(struct perf_event *event)
/*
* Deliver the pending work in-event-context or follow the context.
*/
-static void __perf_pending_irq(struct perf_event *event)
+static void __perf_pending_disable(struct perf_event *event)
{
int cpu = READ_ONCE(event->oncpu);
@@ -6787,11 +6788,26 @@ static void __perf_pending_irq(struct perf_event *event)
* irq_work_queue(); // FAILS
*
* irq_work_run()
- * perf_pending_irq()
+ * perf_pending_disable()
*
* But the event runs on CPU-B and wants disabling there.
*/
- irq_work_queue_on(&event->pending_irq, cpu);
+ irq_work_queue_on(&event->pending_disable_irq, cpu);
+}
+
+static void perf_pending_disable(struct irq_work *entry)
+{
+ struct perf_event *event = container_of(entry, struct perf_event, pending_disable_irq);
+ int rctx;
+
+ /*
+ * If we 'fail' here, that's OK, it means recursion is already disabled
+ * and we won't recurse 'further'.
+ */
+ rctx = perf_swevent_get_recursion_context();
+ __perf_pending_disable(event);
+ if (rctx >= 0)
+ perf_swevent_put_recursion_context(rctx);
}
static void perf_pending_irq(struct irq_work *entry)
@@ -6814,8 +6830,6 @@ static void perf_pending_irq(struct irq_work *entry)
perf_event_wakeup(event);
}
- __perf_pending_irq(event);
-
if (rctx >= 0)
perf_swevent_put_recursion_context(rctx);
}
@@ -11956,6 +11970,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
init_waitqueue_head(&event->waitq);
init_irq_work(&event->pending_irq, perf_pending_irq);
+ event->pending_disable_irq = IRQ_WORK_INIT_HARD(perf_pending_disable);
init_task_work(&event->pending_task, perf_pending_task);
rcuwait_init(&event->pending_work_wait);