From f8da52fb32981cddfe7b0d66180ea7fbda933284 Mon Sep 17 00:00:00 2001
From: Yabin Cui <yabinc@google.com>
Date: Thu, 28 May 2015 20:16:08 -0700
Subject: [PATCH] Perf: Fix the condition to toggle PMU IRQ when CPUs are
hotplugged.
Bug: 19863147
Refactor the interrupt disabling so that interrupts are disabled when
a cpu is hotplugged out, even if there are no perf events on that cpu,
but it holds the PMU irq.
(partially cherry-picked from "Perf: interrupt disable without bringing cpus up")
Change-Id: I9253d6a3bfa51b4b71d3ca51d4c306dd49ca5ef7
---
arch/arm/include/asm/pmu.h | 7 ++++
arch/arm/kernel/perf_event.c | 72 ++++++++++++++++++------------------
arch/arm/mach-msm/pmu.c | 7 ++--
3 files changed, 47 insertions(+), 39 deletions(-)
diff --git a/arch/arm/include/asm/pmu.h b/arch/arm/include/asm/pmu.h
index d1a3e6194817..e6ae480b2bb9 100644
--- a/arch/arm/include/asm/pmu.h
+++ b/arch/arm/include/asm/pmu.h
@@ -25,6 +25,12 @@ enum arm_pmu_type {
ARM_NUM_PMU_DEVICES,
};
+enum arm_pmu_state {
+ ARM_PMU_STATE_OFF = 0,
+ ARM_PMU_STATE_GOING_DOWN,
+ ARM_PMU_STATE_RUNNING,
+};
+
/*
* struct arm_pmu_platdata - ARM PMU platform data
*
@@ -115,6 +121,7 @@ struct arm_pmu {
cpumask_t active_irqs;
const char *name;
int num_events;
+ int pmu_state;
atomic_t active_events;
struct mutex reserve_mutex;
u64 max_period;
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index aed4443011a5..2f04348d62f0 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -405,6 +405,12 @@ armpmu_release_hardware(struct arm_pmu *armpmu)
int i, irq, irqs;
struct platform_device *pmu_device = armpmu->plat_device;
+ /*
+ * If a cpu comes online during this function, do not enable its irq.
+ * If a cpu goes offline, it should disable its irq.
+ */
+ armpmu->pmu_state = ARM_PMU_STATE_GOING_DOWN;
+
irqs = min(pmu_device->num_resources, num_possible_cpus());
for (i = 0; i < irqs; ++i) {
@@ -414,6 +420,8 @@ armpmu_release_hardware(struct arm_pmu *armpmu)
armpmu->free_pmu_irq(irq);
}
+ armpmu->pmu_state = ARM_PMU_STATE_OFF;
+
release_pmu(armpmu->type);
}
@@ -485,6 +493,7 @@ armpmu_reserve_hardware(struct arm_pmu *armpmu)
cpumask_set_cpu(i, &armpmu->active_irqs);
}
+ armpmu->pmu_state = ARM_PMU_STATE_RUNNING;
return 0;
}
@@ -782,50 +791,41 @@ static int __cpuinit pmu_cpu_notify(struct notifier_block *b,
unsigned long action, void *hcpu)
{
int irq;
+ unsigned long masked_action = action & ~CPU_TASKS_FROZEN;
+ int ret = NOTIFY_DONE;
- if (cpu_has_active_perf()) {
- switch ((action & ~CPU_TASKS_FROZEN)) {
-
- case CPU_DOWN_PREPARE:
- /*
- * If this is on a multicore CPU, we need
- * to disarm the PMU IRQ before disappearing.
- */
- if (cpu_pmu &&
- cpu_pmu->plat_device->dev.platform_data) {
+ if ((masked_action != CPU_DOWN_PREPARE) && (masked_action != CPU_STARTING)) {
+ return NOTIFY_DONE;
+ }
+ if (masked_action == CPU_STARTING) {
+ ret = NOTIFY_OK;
+ }
+ switch (masked_action) {
+ case CPU_DOWN_PREPARE:
+ if (cpu_pmu->pmu_state != ARM_PMU_STATE_OFF) {
+ /* Disarm the PMU IRQ before disappearing. */
+ if (cpu_pmu->plat_device) {
irq = platform_get_irq(cpu_pmu->plat_device, 0);
- smp_call_function_single((int)hcpu,
- disable_irq_callback, &irq, 1);
+ smp_call_function_single((int)hcpu, disable_irq_callback, &irq, 1);
}
- return NOTIFY_DONE;
+ }
+ break;
- case CPU_UP_PREPARE:
- /*
- * If this is on a multicore CPU, we need
- * to arm the PMU IRQ before appearing.
- */
- if (cpu_pmu &&
- cpu_pmu->plat_device->dev.platform_data) {
+ case CPU_STARTING:
+ /* Reset PMU to clear counters for ftrace buffer. */
+ if (cpu_pmu->reset) {
+ cpu_pmu->reset(NULL);
+ }
+ if (cpu_pmu->pmu_state == ARM_PMU_STATE_RUNNING) {
+ /* Arm the PMU IRQ before appearing. */
+ if (cpu_pmu->plat_device) {
irq = platform_get_irq(cpu_pmu->plat_device, 0);
- smp_call_function_single((int)hcpu,
- enable_irq_callback, &irq, 1);
- }
- return NOTIFY_DONE;
-
- case CPU_STARTING:
- if (cpu_pmu && cpu_pmu->reset) {
- cpu_pmu->reset(NULL);
- return NOTIFY_OK;
+ enable_irq_callback(&irq);
}
- default:
- return NOTIFY_DONE;
}
+ break;
}
-
- if ((action & ~CPU_TASKS_FROZEN) != CPU_STARTING)
- return NOTIFY_DONE;
-
- return NOTIFY_OK;
+ return ret;
}
static void armpmu_update_counters(void)
diff --git a/arch/arm/mach-msm/pmu.c b/arch/arm/mach-msm/pmu.c
index 8d65eea345e5..2b2de6b38ece 100644
--- a/arch/arm/mach-msm/pmu.c
+++ b/arch/arm/mach-msm/pmu.c
@@ -10,6 +10,7 @@
* GNU General Public License for more details.
*/
+#include <linux/irq.h>
#include <linux/platform_device.h>
#include <asm/pmu.h>
#include <mach/irqs.h>
@@ -41,12 +42,12 @@ static void
multicore_free_irq(int irq)
{
int cpu;
+ struct irq_desc *desc = irq_to_desc(irq);
- if (irq >= 0) {
- for_each_cpu(cpu, cpu_online_mask) {
+ if ((irq >= 0) && desc) {
+ for_each_cpu(cpu, desc->percpu_enabled)
smp_call_function_single(cpu,
disable_irq_callback, &irq, 1);
- }
free_percpu_irq(irq, &pmu_irq_cookie);
}
}
--
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