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authorSebastian Andrzej Siewior <bigeasy@linutronix.de>2016-07-20 09:51:11 +0200
committerIngo Molnar <mingo@kernel.org>2016-07-20 09:57:34 +0200
commit37b502f121adab26ccc2769c3063f0e1272be7de (patch)
tree68e8d160f3344282a5b7d64737b9fed3f5435b75 /drivers/perf
parentc76c15e6f16c1529b524ba2c519c4fcef7a45e16 (diff)
downloadlinux-37b502f121adab26ccc2769c3063f0e1272be7de.tar.bz2
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>
Diffstat (limited to 'drivers/perf')
-rw-r--r--drivers/perf/arm_pmu.c53
1 files changed, 37 insertions, 16 deletions
diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index ae9fc6c6add3..f6ab4f7f75bf 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -685,6 +685,9 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler)
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 cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler)
*/
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 @@ static int cpu_pmu_init(struct arm_pmu *cpu_pmu)
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 @@ static int cpu_pmu_init(struct arm_pmu *cpu_pmu)
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 @@ out_hw_events:
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 @@ int arm_pmu_device_probe(struct platform_device *pdev,
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 @@ out_free:
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);