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Subject[tip:smp/hotplug] x86/x2apic: Convert to CPU hotplug state machine
Commit-ID:  6b2c28471de550308784560206c3365e5179d42f
Gitweb: http://git.kernel.org/tip/6b2c28471de550308784560206c3365e5179d42f
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Wed, 13 Jul 2016 17:17:00 +0000
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 15 Jul 2016 10:41:42 +0200

x86/x2apic: Convert to CPU hotplug state machine

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>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153337.736898691@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/apic/x2apic_cluster.c | 80 +++++++++++++----------------------
include/linux/cpuhotplug.h | 1 +
2 files changed, 31 insertions(+), 50 deletions(-)

diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
index aca8b75..b5da5a8 100644
--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -152,68 +152,48 @@ static void init_x2apic_ldr(void)
}
}

- /*
- * At CPU state changes, update the x2apic cluster sibling info.
- */
-static int
-update_clusterinfo(struct notifier_block *nfb, unsigned long action, void *hcpu)
+/*
+ * At CPU state changes, update the x2apic cluster sibling info.
+ */
+int x2apic_prepare_cpu(unsigned int cpu)
{
- unsigned int this_cpu = (unsigned long)hcpu;
- unsigned int cpu;
- int err = 0;
-
- switch (action) {
- case CPU_UP_PREPARE:
- if (!zalloc_cpumask_var(&per_cpu(cpus_in_cluster, this_cpu),
- GFP_KERNEL)) {
- err = -ENOMEM;
- } else if (!zalloc_cpumask_var(&per_cpu(ipi_mask, this_cpu),
- GFP_KERNEL)) {
- free_cpumask_var(per_cpu(cpus_in_cluster, this_cpu));
- err = -ENOMEM;
- }
- break;
- case CPU_UP_CANCELED:
- case CPU_UP_CANCELED_FROZEN:
- case CPU_DEAD:
- for_each_online_cpu(cpu) {
- if (x2apic_cluster(this_cpu) != x2apic_cluster(cpu))
- continue;
- cpumask_clear_cpu(this_cpu, per_cpu(cpus_in_cluster, cpu));
- cpumask_clear_cpu(cpu, per_cpu(cpus_in_cluster, this_cpu));
- }
- free_cpumask_var(per_cpu(cpus_in_cluster, this_cpu));
- free_cpumask_var(per_cpu(ipi_mask, this_cpu));
- break;
+ if (!zalloc_cpumask_var(&per_cpu(cpus_in_cluster, cpu), GFP_KERNEL))
+ return -ENOMEM;
+
+ if (!zalloc_cpumask_var(&per_cpu(ipi_mask, cpu), GFP_KERNEL)) {
+ free_cpumask_var(per_cpu(cpus_in_cluster, cpu));
+ return -ENOMEM;
}

- return notifier_from_errno(err);
+ return 0;
}

-static struct notifier_block x2apic_cpu_notifier = {
- .notifier_call = update_clusterinfo,
-};
-
-static int x2apic_init_cpu_notifier(void)
+int x2apic_dead_cpu(unsigned int this_cpu)
{
- int cpu = smp_processor_id();
-
- zalloc_cpumask_var(&per_cpu(cpus_in_cluster, cpu), GFP_KERNEL);
- zalloc_cpumask_var(&per_cpu(ipi_mask, cpu), GFP_KERNEL);
+ int cpu;

- BUG_ON(!per_cpu(cpus_in_cluster, cpu) || !per_cpu(ipi_mask, cpu));
-
- cpumask_set_cpu(cpu, per_cpu(cpus_in_cluster, cpu));
- register_hotcpu_notifier(&x2apic_cpu_notifier);
- return 1;
+ for_each_online_cpu(cpu) {
+ if (x2apic_cluster(this_cpu) != x2apic_cluster(cpu))
+ continue;
+ cpumask_clear_cpu(this_cpu, per_cpu(cpus_in_cluster, cpu));
+ cpumask_clear_cpu(cpu, per_cpu(cpus_in_cluster, this_cpu));
+ }
+ free_cpumask_var(per_cpu(cpus_in_cluster, this_cpu));
+ free_cpumask_var(per_cpu(ipi_mask, this_cpu));
+ return 0;
}

static int x2apic_cluster_probe(void)
{
- if (x2apic_mode)
- return x2apic_init_cpu_notifier();
- else
+ int cpu = smp_processor_id();
+
+ if (!x2apic_mode)
return 0;
+
+ cpumask_set_cpu(cpu, per_cpu(cpus_in_cluster, cpu));
+ cpuhp_setup_state(CPUHP_X2APIC_PREPARE, "X2APIC_PREPARE",
+ x2apic_prepare_cpu, x2apic_dead_cpu);
+ return 1;
}

static const struct cpumask *x2apic_cluster_target_cpus(void)
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index ace5ad0..7817082 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -17,6 +17,7 @@ enum cpuhp_state {
CPUHP_WORKQUEUE_PREP,
CPUHP_HRTIMERS_PREPARE,
CPUHP_PROFILE_PREPARE,
+ CPUHP_X2APIC_PREPARE,
CPUHP_TIMERS_DEAD,
CPUHP_NOTIFY_PREPARE,
CPUHP_BRINGUP_CPU,
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