Discussion:
[PATCH 05/22] oprofile/nmi timer: Convert to hotplug state machine
(too old to reply)
Sebastian Andrzej Siewior
2016-11-26 23:13:33 UTC
Permalink
Raw Message
Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Cc: Robert Richter <***@kernel.org>
Cc: oprofile-***@lists.sf.net
Signed-off-by: Sebastian Andrzej Siewior <***@linutronix.de>
---
drivers/oprofile/nmi_timer_int.c | 58 +++++++++++++---------------------------
1 file changed, 19 insertions(+), 39 deletions(-)

diff --git a/drivers/oprofile/nmi_timer_int.c b/drivers/oprofile/nmi_timer_int.c
index 9559829fb234..e65a576e4032 100644
--- a/drivers/oprofile/nmi_timer_int.c
+++ b/drivers/oprofile/nmi_timer_int.c
@@ -59,25 +59,16 @@ static void nmi_timer_stop_cpu(int cpu)
perf_event_disable(event);
}

-static int nmi_timer_cpu_notifier(struct notifier_block *b, unsigned long action,
- void *data)
+static int nmi_timer_cpu_online(unsigned int cpu)
{
- int cpu = (unsigned long)data;
- switch (action) {
- case CPU_DOWN_FAILED:
- case CPU_ONLINE:
- nmi_timer_start_cpu(cpu);
- break;
- case CPU_DOWN_PREPARE:
- nmi_timer_stop_cpu(cpu);
- break;
- }
- return NOTIFY_DONE;
+ nmi_timer_start_cpu(cpu);
+ return 0;
+}
+static int nmi_timer_cpu_predown(unsigned int cpu)
+{
+ nmi_timer_stop_cpu(cpu);
+ return 0;
}
-
-static struct notifier_block nmi_timer_cpu_nb = {
- .notifier_call = nmi_timer_cpu_notifier
-};

static int nmi_timer_start(void)
{
@@ -103,13 +94,14 @@ static void nmi_timer_stop(void)
put_online_cpus();
}

+static enum cpuhp_state hp_online;
+
static void nmi_timer_shutdown(void)
{
struct perf_event *event;
int cpu;

- cpu_notifier_register_begin();
- __unregister_cpu_notifier(&nmi_timer_cpu_nb);
+ cpuhp_remove_state(hp_online);
for_each_possible_cpu(cpu) {
event = per_cpu(nmi_timer_events, cpu);
if (!event)
@@ -118,13 +110,11 @@ static void nmi_timer_shutdown(void)
per_cpu(nmi_timer_events, cpu) = NULL;
perf_event_release_kernel(event);
}
-
- cpu_notifier_register_done();
}

static int nmi_timer_setup(void)
{
- int cpu, err;
+ int err;
u64 period;

/* clock cycles per tick: */
@@ -132,24 +122,14 @@ static int nmi_timer_setup(void)
do_div(period, HZ);
nmi_timer_attr.sample_period = period;

- cpu_notifier_register_begin();
- err = __register_cpu_notifier(&nmi_timer_cpu_nb);
- if (err)
- goto out;
-
- /* can't attach events to offline cpus: */
- for_each_online_cpu(cpu) {
- err = nmi_timer_start_cpu(cpu);
- if (err) {
- cpu_notifier_register_done();
- nmi_timer_shutdown();
- return err;
- }
+ err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "oprofile/nmi:online",
+ nmi_timer_cpu_online, nmi_timer_cpu_predown);
+ if (err < 0) {
+ nmi_timer_shutdown();
+ return err;
}
-
-out:
- cpu_notifier_register_done();
- return err;
+ hp_online = err;
+ return 0;
}

int __init op_nmi_timer_init(struct oprofile_operations *ops)
--
2.10.2


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