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Subject[tip:smp/hotplug] x86/oprofile/nmi: Convert to hotplug state machine
Commit-ID:  cff817393431c3cc6fc3eaaeb8511ee0d16116aa
Gitweb: http://git.kernel.org/tip/cff817393431c3cc6fc3eaaeb8511ee0d16116aa
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Thu, 17 Nov 2016 19:35:40 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Mon, 21 Nov 2016 16:37:09 +0100

x86/oprofile/nmi: Convert to 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>
Cc: Robert Richter <rric@kernel.org>
Cc: oprofile-list@lists.sf.net
Cc: rt@linuxtronix.de
Link: http://lkml.kernel.org/r/20161117183541.8588-20-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
arch/x86/oprofile/nmi_int.c | 61 +++++++++++++--------------------------------
1 file changed, 18 insertions(+), 43 deletions(-)

diff --git a/arch/x86/oprofile/nmi_int.c b/arch/x86/oprofile/nmi_int.c
index c39172c..ffdbc48 100644
--- a/arch/x86/oprofile/nmi_int.c
+++ b/arch/x86/oprofile/nmi_int.c
@@ -339,10 +339,11 @@ fail:
return 0;
}

-static void nmi_cpu_setup(void *dummy)
+static void nmi_cpu_setup(void)
{
int cpu = smp_processor_id();
struct op_msrs *msrs = &per_cpu(cpu_msrs, cpu);
+
nmi_cpu_save_registers(msrs);
raw_spin_lock(&oprofilefs_lock);
model->setup_ctrs(model, msrs);
@@ -369,7 +370,7 @@ static void nmi_cpu_restore_registers(struct op_msrs *msrs)
}
}

-static void nmi_cpu_shutdown(void *dummy)
+static void nmi_cpu_shutdown(void)
{
unsigned int v;
int cpu = smp_processor_id();
@@ -387,24 +388,26 @@ static void nmi_cpu_shutdown(void *dummy)
nmi_cpu_restore_registers(msrs);
}

-static void nmi_cpu_up(void)
+static int nmi_cpu_online(unsigned int cpu)
{
local_irq_disable();
if (nmi_enabled)
- nmi_cpu_setup(NULL);
+ nmi_cpu_setup();
if (ctr_running)
nmi_cpu_start(NULL);
local_irq_enable();
+ return 0;
}

-static void nmi_cpu_down(void)
+static int nmi_cpu_down_prep(unsigned int cpu)
{
local_irq_disable();
if (ctr_running)
nmi_cpu_stop(NULL);
if (nmi_enabled)
- nmi_cpu_shutdown(NULL);
+ nmi_cpu_shutdown();
local_irq_enable();
+ return 0;
}

static int nmi_create_files(struct dentry *root)
@@ -437,24 +440,7 @@ static int nmi_create_files(struct dentry *root)
return 0;
}

-static int oprofile_cpu_notifier(struct notifier_block *b, unsigned long action,
- void *data)
-{
- switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_DOWN_FAILED:
- case CPU_ONLINE:
- nmi_cpu_up();
- break;
- case CPU_DOWN_PREPARE:
- nmi_cpu_down();
- break;
- }
- return NOTIFY_DONE;
-}
-
-static struct notifier_block oprofile_cpu_nb = {
- .notifier_call = oprofile_cpu_notifier
-};
+static enum cpuhp_state cpuhp_nmi_online;

static int nmi_setup(void)
{
@@ -497,20 +483,17 @@ static int nmi_setup(void)
if (err)
goto fail;

- cpu_notifier_register_begin();
-
- /* Use get/put_online_cpus() to protect 'nmi_enabled' */
- get_online_cpus();
nmi_enabled = 1;
/* make nmi_enabled visible to the nmi handler: */
smp_mb();
- on_each_cpu(nmi_cpu_setup, NULL, 1);
- __register_cpu_notifier(&oprofile_cpu_nb);
- put_online_cpus();
-
- cpu_notifier_register_done();
-
+ err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/oprofile:online",
+ nmi_cpu_online, nmi_cpu_down_prep);
+ if (err < 0)
+ goto fail_nmi;
+ cpuhp_nmi_online = err;
return 0;
+fail_nmi:
+ unregister_nmi_handler(NMI_LOCAL, "oprofile");
fail:
free_msrs();
return err;
@@ -520,17 +503,9 @@ static void nmi_shutdown(void)
{
struct op_msrs *msrs;

- cpu_notifier_register_begin();
-
- /* Use get/put_online_cpus() to protect 'nmi_enabled' & 'ctr_running' */
- get_online_cpus();
- on_each_cpu(nmi_cpu_shutdown, NULL, 1);
+ cpuhp_remove_state(cpuhp_nmi_online);
nmi_enabled = 0;
ctr_running = 0;
- __unregister_cpu_notifier(&oprofile_cpu_nb);
- put_online_cpus();
-
- cpu_notifier_register_done();

/* make variables visible to the nmi handler: */
smp_mb();
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