[RFC PATCH 1/6] stop_machine: move cpu_stopper_task and stop_cpus_work into struct cpu_stopper

From: Oleg Nesterov
Date: Thu Jun 25 2015 - 22:16:39 EST


Multpiple DEFINE_PER_CPU's do not make sense, move all the per-cpu
variables into struct cpu_stopper.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
kernel/stop_machine.c | 17 +++++++++--------
1 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index fd643d8..6e677b0 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -35,13 +35,16 @@ struct cpu_stop_done {

/* the actual stopper, one per every possible cpu, enabled on online cpus */
struct cpu_stopper {
+ struct task_struct *thread;
+
spinlock_t lock;
bool enabled; /* is this stopper enabled? */
struct list_head works; /* list of pending works */
+
+ struct cpu_stop_work stop_work; /* for stop_cpus */
};

static DEFINE_PER_CPU(struct cpu_stopper, cpu_stopper);
-static DEFINE_PER_CPU(struct task_struct *, cpu_stopper_task);
static bool stop_machine_initialized = false;

/*
@@ -74,7 +77,6 @@ static void cpu_stop_signal_done(struct cpu_stop_done *done, bool executed)
static void cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
{
struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
- struct task_struct *p = per_cpu(cpu_stopper_task, cpu);

unsigned long flags;

@@ -82,7 +84,7 @@ static void cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)

if (stopper->enabled) {
list_add_tail(&work->list, &stopper->works);
- wake_up_process(p);
+ wake_up_process(stopper->thread);
} else
cpu_stop_signal_done(work->done, false);

@@ -293,7 +295,6 @@ void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,

/* static data for stop_cpus */
static DEFINE_MUTEX(stop_cpus_mutex);
-static DEFINE_PER_CPU(struct cpu_stop_work, stop_cpus_work);

static void queue_stop_cpus_work(const struct cpumask *cpumask,
cpu_stop_fn_t fn, void *arg,
@@ -304,7 +305,7 @@ static void queue_stop_cpus_work(const struct cpumask *cpumask,

/* initialize works and done */
for_each_cpu(cpu, cpumask) {
- work = &per_cpu(stop_cpus_work, cpu);
+ work = &per_cpu(cpu_stopper.stop_work, cpu);
work->fn = fn;
work->arg = arg;
work->done = done;
@@ -317,7 +318,7 @@ static void queue_stop_cpus_work(const struct cpumask *cpumask,
*/
lg_global_lock(&stop_cpus_lock);
for_each_cpu(cpu, cpumask)
- cpu_stop_queue_work(cpu, &per_cpu(stop_cpus_work, cpu));
+ cpu_stop_queue_work(cpu, &per_cpu(cpu_stopper.stop_work, cpu));
lg_global_unlock(&stop_cpus_lock);
}

@@ -458,7 +459,7 @@ extern void sched_set_stop_task(int cpu, struct task_struct *stop);

static void cpu_stop_create(unsigned int cpu)
{
- sched_set_stop_task(cpu, per_cpu(cpu_stopper_task, cpu));
+ sched_set_stop_task(cpu, per_cpu(cpu_stopper.thread, cpu));
}

static void cpu_stop_park(unsigned int cpu)
@@ -485,7 +486,7 @@ static void cpu_stop_unpark(unsigned int cpu)
}

static struct smp_hotplug_thread cpu_stop_threads = {
- .store = &cpu_stopper_task,
+ .store = &cpu_stopper.thread,
.thread_should_run = cpu_stop_should_run,
.thread_fn = cpu_stopper_thread,
.thread_comm = "migration/%u",
--
1.5.5.1

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