Commit-ID: 37b502f121adab26ccc2769c3063f0e1272be7de
Gitweb: http://git.kernel.org/tip/37b502f121adab26ccc2769c3063f0e1272be7de
Author: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
AuthorDate: Wed, 20 Jul 2016 09:51:11 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 20 Jul 2016 09:57:34 +0200
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@xxxxxxxxxxxxx>
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Anna-Maria Gleixner <anna-maria@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: linux-tip-commits@xxxxxxxxxxxxxxx
Cc: rt@xxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20160719111733.GA22911@xxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
drivers/perf/arm_pmu.c | 53 +++++++++++++++++++++++++++++++-------------
include/linux/perf/arm_pmu.h | 1 +
2 files changed, 38 insertions(+), 16 deletions(-)
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 @@ 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);
diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
index e6ed34e..e188438 100644
--- a/include/linux/perf/arm_pmu.h
+++ b/include/linux/perf/arm_pmu.h
@@ -109,6 +109,7 @@ struct arm_pmu {
DECLARE_BITMAP(pmceid_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS);
struct platform_device *plat_device;
struct pmu_hw_events __percpu *hw_events;
+ struct list_head entry;
struct notifier_block cpu_pm_nb;
};
--
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