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Subject[patch V2 23/67] bus/arm-ccn: Convert to hotplug statemachine
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
---
drivers/bus/arm-ccn.c | 57 ++++++++++++++++++++++-----------------------
include/linux/cpuhotplug.h | 1
2 files changed, 29 insertions(+), 29 deletions(-)

--- a/drivers/bus/arm-ccn.c
+++ b/drivers/bus/arm-ccn.c
@@ -167,7 +167,7 @@ struct arm_ccn_dt {
struct hrtimer hrtimer;

cpumask_t cpu;
- struct notifier_block cpu_nb;
+ struct list_head entry;

struct pmu pmu;
};
@@ -189,6 +189,8 @@ struct arm_ccn {
struct arm_ccn_dt dt;
};

+static DEFINE_MUTEX(arm_ccn_mutex);
+static LIST_HEAD(arm_ccn_list);

static int arm_ccn_node_to_xp(int node)
{
@@ -1171,30 +1173,27 @@ static enum hrtimer_restart arm_ccn_pmu_
}


-static int arm_ccn_pmu_cpu_notifier(struct notifier_block *nb,
- unsigned long action, void *hcpu)
+static int arm_ccn_pmu_offline_cpu(unsigned int cpu)
{
- struct arm_ccn_dt *dt = container_of(nb, struct arm_ccn_dt, cpu_nb);
- struct arm_ccn *ccn = container_of(dt, struct arm_ccn, dt);
- unsigned int cpu = (long)hcpu; /* for (long) see kernel/cpu.c */
+ struct arm_ccn_dt *dt;
unsigned int target;

- switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_DOWN_PREPARE:
+ mutex_lock(&arm_ccn_mutex);
+ list_for_each_entry(dt, &arm_ccn_list, entry) {
+ struct arm_ccn *ccn = container_of(dt, struct arm_ccn, dt);
+
if (!cpumask_test_and_clear_cpu(cpu, &dt->cpu))
- break;
+ continue;
target = cpumask_any_but(cpu_online_mask, cpu);
if (target >= nr_cpu_ids)
- break;
+ continue;
perf_pmu_migrate_context(&dt->pmu, cpu, target);
cpumask_set_cpu(target, &dt->cpu);
if (ccn->irq)
WARN_ON(irq_set_affinity_hint(ccn->irq, &dt->cpu) != 0);
- default:
- break;
}
-
- return NOTIFY_OK;
+ mutex_unlock(&arm_ccn_mutex);
+ return 0;
}


@@ -1266,16 +1265,6 @@ static int arm_ccn_pmu_init(struct arm_c
/* Pick one CPU which we will use to collect data from CCN... */
cpumask_set_cpu(smp_processor_id(), &ccn->dt.cpu);

- /*
- * ... and change the selection when it goes offline. Priority is
- * picked to have a chance to migrate events before perf is notified.
- */
- ccn->dt.cpu_nb.notifier_call = arm_ccn_pmu_cpu_notifier;
- ccn->dt.cpu_nb.priority = CPU_PRI_PERF + 1,
- err = register_cpu_notifier(&ccn->dt.cpu_nb);
- if (err)
- goto error_cpu_notifier;
-
/* Also make sure that the overflow interrupt is handled by this CPU */
if (ccn->irq) {
err = irq_set_affinity_hint(ccn->irq, &ccn->dt.cpu);
@@ -1289,12 +1278,13 @@ static int arm_ccn_pmu_init(struct arm_c
if (err)
goto error_pmu_register;

+ mutex_lock(&arm_ccn_mutex);
+ list_add(&ccn->dt.entry, &arm_ccn_list);
+ mutex_unlock(&arm_ccn_mutex);
return 0;

error_pmu_register:
error_set_affinity:
- unregister_cpu_notifier(&ccn->dt.cpu_nb);
-error_cpu_notifier:
ida_simple_remove(&arm_ccn_pmu_ida, ccn->dt.id);
for (i = 0; i < ccn->num_xps; i++)
writel(0, ccn->xp[i].base + CCN_XP_DT_CONTROL);
@@ -1306,9 +1296,12 @@ static void arm_ccn_pmu_cleanup(struct a
{
int i;

+ mutex_lock(&arm_ccn_mutex);
+ list_del(&ccn->dt.entry);
+ mutex_unlock(&arm_ccn_mutex);
+
if (ccn->irq)
irq_set_affinity_hint(ccn->irq, NULL);
- unregister_cpu_notifier(&ccn->dt.cpu_nb);
for (i = 0; i < ccn->num_xps; i++)
writel(0, ccn->xp[i].base + CCN_XP_DT_CONTROL);
writel(0, ccn->dt.base + CCN_DT_PMCR);
@@ -1316,7 +1309,6 @@ static void arm_ccn_pmu_cleanup(struct a
ida_simple_remove(&arm_ccn_pmu_ida, ccn->dt.id);
}

-
static int arm_ccn_for_each_valid_region(struct arm_ccn *ccn,
int (*callback)(struct arm_ccn *ccn, int region,
void __iomem *base, u32 type, u32 id))
@@ -1533,7 +1525,13 @@ static struct platform_driver arm_ccn_dr

static int __init arm_ccn_init(void)
{
- int i;
+ int i, ret;
+
+ ret = cpuhp_setup_state_nocalls(CPUHP_AP_PERF_ARM_CCN_ONLINE,
+ "AP_PERF_ARM_CCN_ONLINE", NULL,
+ arm_ccn_pmu_offline_cpu);
+ if (ret)
+ return ret;

for (i = 0; i < ARRAY_SIZE(arm_ccn_pmu_events); i++)
arm_ccn_pmu_events_attrs[i] = &arm_ccn_pmu_events[i].attr.attr;
@@ -1543,6 +1541,7 @@ static int __init arm_ccn_init(void)

static void __exit arm_ccn_exit(void)
{
+ cpuhp_remove_state_nocalls(CPUHP_AP_PERF_ARM_CCN_ONLINE);
platform_driver_unregister(&arm_ccn_driver);
}

--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -46,6 +46,7 @@ enum cpuhp_state {
CPUHP_AP_PERF_S390_CF_ONLINE,
CPUHP_AP_PERF_S390_SF_ONLINE,
CPUHP_AP_PERF_ARM_CCI_ONLINE,
+ CPUHP_AP_PERF_ARM_CCN_ONLINE,
CPUHP_AP_NOTIFY_ONLINE,
CPUHP_AP_ONLINE_DYN,
CPUHP_AP_ONLINE_DYN_END = CPUHP_AP_ONLINE_DYN + 30,

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