Commit db417646 authored by Thomas Richter's avatar Thomas Richter Committed by Heiko Carstens
Browse files

s390/cpum_sf: Do not re-enable event after deletion 



Event delete removes an event from the event list, but common
code invokes the PMU's enable function later on. This happens
in event_sched_out() and leads to the following call sequence:

  event_sched_out()
  +--> cpumsf_pmu_del()
  +--> cpumsf_pmu_enable()

In cpumsf_pmu_enable() return immediately when the event is not
active. Also remove an unneeded if clause. That if() statement
is only reached when flag PMU_F_IN_USE has been set in
cpumsf_pmu_add(). And this function also sets cpuhw->event
to a valid value.

Remove WARN_ON_ONCE() statement which never triggered.

Signed-off-by: default avatarThomas Richter <tmricht@linux.ibm.com>
Reviewed-by: default avatarHendrik Brueckner <brueckner@linux.ibm.com>
Acked-by: default avatarSumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent e7277a89

arch/s390/kernel/perf_cpum_sf.c

+19 −19
Original line number Diff line number Diff line
@@ -910,10 +910,14 @@ static void cpumsf_pmu_enable(struct pmu *pmu) 
	struct hw_perf_event *hwc;

	int err;



	if (cpuhw->flags & PMU_F_ENABLED)

		return;



	if (cpuhw->flags & PMU_F_ERR_MASK)

	/*

	 * Event must be

	 * - added/started on this CPU (PMU_F_IN_USE set)

	 * - and CPU must be available (PMU_F_RESERVED set)

	 * - and not already enabled (PMU_F_ENABLED not set)

	 * - and not in error condition (PMU_F_ERR_MASK not set)

	 */

	if (cpuhw->flags != (PMU_F_IN_USE | PMU_F_RESERVED))

		return;



	/* Check whether to extent the sampling buffer.
@@ -927,19 +931,16 @@ static void cpumsf_pmu_enable(struct pmu *pmu) 
	 * facility, but it can be fully re-enabled using sampling controls that

	 * have been saved in cpumsf_pmu_disable().

	 */

	if (cpuhw->event) {

	hwc = &cpuhw->event->hw;

	if (!(SAMPL_DIAG_MODE(hwc))) {

		/*

			 * Account number of overflow-designated

			 * buffer extents

		 * Account number of overflow-designated buffer extents

		 */

		sfb_account_overflows(cpuhw, hwc);

		extend_sampling_buffer(&cpuhw->sfb, hwc);

	}

	/* Rate may be adjusted with ioctl() */

	cpuhw->lsctl.interval = SAMPL_RATE(hwc);

	}



	/* (Re)enable the PMU and sampling facility */

	err = lsctl(&cpuhw->lsctl);
@@ -1954,13 +1955,12 @@ static void cpumf_measurement_alert(struct ext_code ext_code, 


	/* Program alert request */

	if (alert & CPU_MF_INT_SF_PRA) {

		if (cpuhw->flags & PMU_F_IN_USE)

		if (cpuhw->flags & PMU_F_IN_USE) {

			if (SAMPL_DIAG_MODE(&cpuhw->event->hw))

				hw_collect_aux(cpuhw);

			else

				hw_perf_event_update(cpuhw->event, 0);

		else

			WARN_ON_ONCE(!(cpuhw->flags & PMU_F_IN_USE));

		}

	}



	/* Report measurement alerts only for non-PRA codes */