Commit 2fc18d0b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'perf_urgent_for_v6.16_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull perf fix from Borislav Petkov:

 - Make sure an AUX perf event is really disabled when it overruns

* tag 'perf_urgent_for_v6.16_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/aux: Fix pending disable flow when the AUX ring buffer overruns
parents 753a0f61 1476b218

kernel/events/core.c

+3 −3
Original line number Diff line number Diff line
@@ -7251,15 +7251,15 @@ static void __perf_pending_disable(struct perf_event *event) 
	 *  CPU-A			CPU-B

	 *

	 *  perf_event_disable_inatomic()

	 *    @pending_disable = CPU-A;

	 *    @pending_disable = 1;

	 *    irq_work_queue();

	 *

	 *  sched-out

	 *    @pending_disable = -1;

	 *    @pending_disable = 0;

	 *

	 *				sched-in

	 *				perf_event_disable_inatomic()

	 *				  @pending_disable = CPU-B;

	 *				  @pending_disable = 1;

	 *				  irq_work_queue(); // FAILS

	 *

	 *  irq_work_run()

kernel/events/ring_buffer.c

+2 −2
Original line number Diff line number Diff line
@@ -441,7 +441,7 @@ void *perf_aux_output_begin(struct perf_output_handle *handle, 
		 * store that will be enabled on successful return

		 */

		if (!handle->size) { /* A, matches D */

			event->pending_disable = smp_processor_id();

			perf_event_disable_inatomic(handle->event);

			perf_output_wakeup(handle);

			WRITE_ONCE(rb->aux_nest, 0);

			goto err_put;
@@ -526,7 +526,7 @@ void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size) 


	if (wakeup) {

		if (handle->aux_flags & PERF_AUX_FLAG_TRUNCATED)

			handle->event->pending_disable = smp_processor_id();

			perf_event_disable_inatomic(handle->event);

		perf_output_wakeup(handle);

	}