perf: Move irq_work_queue() where the event is prepared.

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.

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/20240704170424.1466941-2-bigeasy@linutronix.de

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 32c7996a4c022ca49639fef83ce782b8e1fc231d..c54da50a706920dcfd3d165b9c3e32420f7b9f76 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9727,6 +9727,11 @@ static int __perf_event_overflow(struct perf_event *event,
                if (!event->pending_sigtrap) {
                        event->pending_sigtrap = pending_id;
                        local_inc(&event->ctx->nr_pending);
+
+                       event->pending_addr = 0;
+                       if (valid_sample && (data->sample_flags & PERF_SAMPLE_ADDR))
+                               event->pending_addr = data->addr;
+                       irq_work_queue(&event->pending_irq);
                } else if (event->attr.exclude_kernel && valid_sample) {
                        /*
                         * Should not be able to return to user space without
@@ -9742,11 +9747,6 @@ static int __perf_event_overflow(struct perf_event *event,
                         */
                        WARN_ON_ONCE(event->pending_sigtrap != pending_id);
                }
-
-               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);