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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Tue, 12 Mar 2024 19:01:49 +0100
Subject: [PATCH 1/4] perf: Move irq_work_queue() where the event is prepared.
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.9/older/patches-6.9-rt5.tar.xz
Only if perf_event::pending_sigtrap is zero, the irq_work accounted by
increminging perf_event::nr_pending. The member perf_event::pending_addr
might be overwritten by a subsequent event if the signal was not yet
delivered and is expected. The irq_work will not be enqeueued again
because it has a check to be only enqueued once.
Move irq_work_queue() to where the counter is incremented and
perf_event::pending_sigtrap is set to make it more obvious that the
irq_work is scheduled once.
Tested-by: Marco Elver <elver@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lore.kernel.org/r/20240312180814.3373778-2-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/events/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9591,6 +9591,7 @@ static int __perf_event_overflow(struct
if (!event->pending_sigtrap) {
event->pending_sigtrap = pending_id;
local_inc(&event->ctx->nr_pending);
+ irq_work_queue(&event->pending_irq);
} else if (event->attr.exclude_kernel && valid_sample) {
/*
* Should not be able to return to user space without
@@ -9610,7 +9611,6 @@ static int __perf_event_overflow(struct
event->pending_addr = 0;
if (valid_sample && (data->sample_flags & PERF_SAMPLE_ADDR))
event->pending_addr = data->addr;
- irq_work_queue(&event->pending_irq);
}
READ_ONCE(event->overflow_handler)(event, data, regs);
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