[PATCH 3/5] perf: Fix event_function_call() locking

Peter Zijlstra
2024-08-07T11:56:30Z

All the event_function/@func call context already uses perf_ctx_lock()
except for the !ctx->is_active case. Make it all consistent.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/events/core.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -263,6 +263,7 @@ static int event_function(void *info)
static void event_function_call(struct perf_event *event, event_f func, void *data)
{
struct perf_event_context *ctx = event->ctx;
+ struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
struct task_struct *task = READ_ONCE(ctx->task); /* verified in event_function */
struct event_function_struct efs = {
.event = event,
@@ -291,22 +292,22 @@ static void event_function_call(struct p
if (!task_function_call(task, event_function, &efs))
return;

- raw_spin_lock_irq(&ctx->lock);
+ perf_ctx_lock(cpuctx, ctx);
/*
* Reload the task pointer, it might have been changed by
* a concurrent perf_event_context_sched_out().
*/
task = ctx->task;
if (task == TASK_TOMBSTONE) {
- raw_spin_unlock_irq(&ctx->lock);
+ perf_ctx_unlock(cpuctx, ctx);
return;
}
if (ctx->is_active) {
- raw_spin_unlock_irq(&ctx->lock);
+ perf_ctx_unlock(cpuctx, ctx);
goto again;
}
func(event, NULL, ctx, data);
- raw_spin_unlock_irq(&ctx->lock);
+ perf_ctx_unlock(cpuctx, ctx);
}

/*