arm/perf: Fix hotplug state machine conversion
Mark Rutland pointed out that this commit is incomplete:
7d88eb695a1f ("arm/perf: Convert to hotplug state machine")
The problem is that:
> We may have multiple PMUs (e.g. two in big.LITTLE systems), and
> __oprofile_cpu_pmu only contains one of these. So this conversion is not
> correct.
>
> We were relying on the notifier list implicitly containing a list of
> those PMUs. It seems like we need an explicit list here.
>
> We keep __oprofile_cpu_pmu around for legacy 32-bit users of OProfile
> (on non-hetereogeneous systems), and that's all that the variable should
> be used for.
Introduce arm_pmu_list to correctly handle multiple PMUs in the system.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-tip-commits@vger.kernel.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160719111733.GA22911@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index ae9fc6c..f6ab4f7 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -685,6 +685,9 @@
return 0;
}
+static DEFINE_MUTEX(arm_pmu_mutex);
+static LIST_HEAD(arm_pmu_list);
+
/*
* PMU hardware loses all context when a CPU goes offline.
* When a CPU is hotplugged back in, since some hardware registers are
@@ -693,12 +696,17 @@
*/
static int arm_perf_starting_cpu(unsigned int cpu)
{
- if (!__oprofile_cpu_pmu)
- return 0;
- if (!cpumask_test_cpu(cpu, &__oprofile_cpu_pmu->supported_cpus))
- return 0;
- if (__oprofile_cpu_pmu->reset)
- __oprofile_cpu_pmu->reset(__oprofile_cpu_pmu);
+ struct arm_pmu *pmu;
+
+ mutex_lock(&arm_pmu_mutex);
+ list_for_each_entry(pmu, &arm_pmu_list, entry) {
+
+ if (!cpumask_test_cpu(cpu, &pmu->supported_cpus))
+ continue;
+ if (pmu->reset)
+ pmu->reset(pmu);
+ }
+ mutex_unlock(&arm_pmu_mutex);
return 0;
}
@@ -810,11 +818,9 @@
if (!cpu_hw_events)
return -ENOMEM;
- err = cpuhp_setup_state_nocalls(CPUHP_AP_PERF_ARM_STARTING,
- "AP_PERF_ARM_STARTING",
- arm_perf_starting_cpu, NULL);
- if (err)
- goto out_hw_events;
+ mutex_lock(&arm_pmu_mutex);
+ list_add_tail(&cpu_pmu->entry, &arm_pmu_list);
+ mutex_unlock(&arm_pmu_mutex);
err = cpu_pm_pmu_register(cpu_pmu);
if (err)
@@ -850,8 +856,9 @@
return 0;
out_unregister:
- cpuhp_remove_state_nocalls(CPUHP_AP_PERF_ARM_STARTING);
-out_hw_events:
+ mutex_lock(&arm_pmu_mutex);
+ list_del(&cpu_pmu->entry);
+ mutex_unlock(&arm_pmu_mutex);
free_percpu(cpu_hw_events);
return err;
}
@@ -859,7 +866,9 @@
static void cpu_pmu_destroy(struct arm_pmu *cpu_pmu)
{
cpu_pm_pmu_unregister(cpu_pmu);
- cpuhp_remove_state_nocalls(CPUHP_AP_PERF_ARM_STARTING);
+ mutex_lock(&arm_pmu_mutex);
+ list_del(&cpu_pmu->entry);
+ mutex_unlock(&arm_pmu_mutex);
free_percpu(cpu_pmu->hw_events);
}
@@ -1019,8 +1028,6 @@
if (ret)
goto out_destroy;
- WARN(__oprofile_cpu_pmu, "%s(): missing PMU strucure for CPU-hotplug\n",
- __func__);
if (!__oprofile_cpu_pmu)
__oprofile_cpu_pmu = pmu;
@@ -1038,3 +1045,17 @@
kfree(pmu);
return ret;
}
+
+static int arm_pmu_hp_init(void)
+{
+ int ret;
+
+ ret = cpuhp_setup_state_nocalls(CPUHP_AP_PERF_ARM_STARTING,
+ "AP_PERF_ARM_STARTING",
+ arm_perf_starting_cpu, NULL);
+ if (ret)
+ pr_err("CPU hotplug notifier for ARM PMU could not be registered: %d\n",
+ ret);
+ return ret;
+}
+subsys_initcall(arm_pmu_hp_init);