drivers/perf: arm-pmu: fix RCU usage on pmu resume from low-power

[deliverable/linux.git] / drivers / perf / arm_pmu.c

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 32346b5a8a119789c1857c90ec13902616ace318..f70090897fdf19c9777c332401dd01de7b1efc52 100644 (file)
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -737,8 +737,19 @@ static void cpu_pm_pmu_setup(struct arm_pmu *armpmu, unsigned long cmd)
                        break;
                case CPU_PM_EXIT:
                case CPU_PM_ENTER_FAILED:
-                        /* Restore and enable the counter */
-                       armpmu_start(event, PERF_EF_RELOAD);
+                        /*
+                         * Restore and enable the counter.
+                         * armpmu_start() indirectly calls
+                         *
+                         * perf_event_update_userpage()
+                         *
+                         * that requires RCU read locking to be functional,
+                         * wrap the call within RCU_NONIDLE to make the
+                         * RCU subsystem aware this cpu is not idle from
+                         * an RCU perspective for the armpmu_start() call
+                         * duration.
+                         */
+                       RCU_NONIDLE(armpmu_start(event, PERF_EF_RELOAD));
                        break;
                default:
                        break;