linux-kernel - [tip:smp/hotplug] bus/arm-cci: Use cpu-hp's multi instance support instead custom list

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Date:   Fri, 2 Sep 2016 11:17:36 -0700
From:   tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     bigeasy@...utronix.de, linux-kernel@...r.kernel.org,
        peterz@...radead.org, will.deacon@....com, olof@...om.net,
        tglx@...utronix.de, suzuki.poulose@....com, mingo@...nel.org,
        mark.rutland@....com, hpa@...or.com
Subject: [tip:smp/hotplug] bus/arm-cci: Use cpu-hp's multi instance support
 instead custom list

Commit-ID:  b230f0db913136f465a951806f2978b179df95d5
Gitweb:     http://git.kernel.org/tip/b230f0db913136f465a951806f2978b179df95d5
Author:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate: Fri, 12 Aug 2016 19:49:41 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Fri, 2 Sep 2016 20:05:06 +0200

bus/arm-cci: Use cpu-hp's multi instance support instead custom list

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Suzuki K Poulose <suzuki.poulose@....com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Will Deacon <will.deacon@....com>
Cc: rt@...utronix.de
Cc: Olof Johansson <olof@...om.net>
Link: http://lkml.kernel.org/r/1471024183-12666-5-git-send-email-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 drivers/bus/arm-cci.c | 45 ++++++++++++++++++---------------------------
 1 file changed, 18 insertions(+), 27 deletions(-)

diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index 5755907f..4c44ba2 100644
--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -144,15 +144,12 @@ struct cci_pmu {
 	int num_cntrs;
 	atomic_t active_events;
 	struct mutex reserve_mutex;
-	struct list_head entry;
+	struct hlist_node node;
 	cpumask_t cpus;
 };
 
 #define to_cci_pmu(c)	(container_of(c, struct cci_pmu, pmu))
 
-static DEFINE_MUTEX(cci_pmu_mutex);
-static LIST_HEAD(cci_pmu_list);
-
 enum cci_models {
 #ifdef CONFIG_ARM_CCI400_PMU
 	CCI400_R0,
@@ -1506,25 +1503,21 @@ static int cci_pmu_init(struct cci_pmu *cci_pmu, struct platform_device *pdev)
 	return perf_pmu_register(&cci_pmu->pmu, name, -1);
 }
 
-static int cci_pmu_offline_cpu(unsigned int cpu)
+static int cci_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node)
 {
-	struct cci_pmu *cci_pmu;
+	struct cci_pmu *cci_pmu = hlist_entry_safe(node, struct cci_pmu, node);
 	unsigned int target;
 
-	mutex_lock(&cci_pmu_mutex);
-	list_for_each_entry(cci_pmu, &cci_pmu_list, entry) {
-		if (!cpumask_test_and_clear_cpu(cpu, &cci_pmu->cpus))
-			continue;
-		target = cpumask_any_but(cpu_online_mask, cpu);
-		if (target >= nr_cpu_ids)
-			continue;
-		/*
-		 * TODO: migrate context once core races on event->ctx have
-		 * been fixed.
-		 */
-		cpumask_set_cpu(target, &cci_pmu->cpus);
-	}
-	mutex_unlock(&cci_pmu_mutex);
+	if (!cpumask_test_and_clear_cpu(cpu, &cci_pmu->cpus))
+		return 0;
+	target = cpumask_any_but(cpu_online_mask, cpu);
+	if (target >= nr_cpu_ids)
+		return 0;
+	/*
+	 * TODO: migrate context once core races on event->ctx have
+	 * been fixed.
+	 */
+	cpumask_set_cpu(target, &cci_pmu->cpus);
 	return 0;
 }
 
@@ -1768,10 +1761,8 @@ static int cci_pmu_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	mutex_lock(&cci_pmu_mutex);
-	list_add(&cci_pmu->entry, &cci_pmu_list);
-	mutex_unlock(&cci_pmu_mutex);
-
+	cpuhp_state_add_instance_nocalls(CPUHP_AP_PERF_ARM_CCI_ONLINE,
+					 &cci_pmu->node);
 	pr_info("ARM %s PMU driver probed", cci_pmu->model->name);
 	return 0;
 }
@@ -1804,9 +1795,9 @@ static int __init cci_platform_init(void)
 {
 	int ret;
 
-	ret = cpuhp_setup_state_nocalls(CPUHP_AP_PERF_ARM_CCI_ONLINE,
-					"AP_PERF_ARM_CCI_ONLINE", NULL,
-					cci_pmu_offline_cpu);
+	ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_CCI_ONLINE,
+				      "AP_PERF_ARM_CCI_ONLINE", NULL,
+				      cci_pmu_offline_cpu);
 	if (ret)
 		return ret;