Commit 558abc7e authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

perf: Fix event_function_call() locking 



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: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarKan Liang <kan.liang@linux.intel.com>
Reviewed-by: default avatarNamhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240807115550.138301094@infradead.org
parent 9a32bd99

kernel/events/core.c

+5 −4
Original line number Diff line number Diff line
@@ -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 perf_event *event, event_f func, void *da 
	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);

}



/*