[tip:locking/core] stop_machine: Use raw spinlocks

tip-bot for Thomas Gleixner
2018-04-27T12:40:20Z

Commit-ID: de5b55c1d4e30740009864eb35ce4ed856aac01d
Gitweb: https://git.kernel.org/tip/de5b55c1d4e30740009864eb35ce4ed856aac01d
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Mon, 23 Apr 2018 21:16:35 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 27 Apr 2018 14:34:51 +0200

stop_machine: Use raw spinlocks

Use raw-locks in stop_machine() to allow locking in irq-off and
preempt-disabled regions on -RT. This also documents the possible locking
context in general.

[bigeasy: update patch description.]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lkml.kernel.org/r/20180423191635.6014-1-bigeasy@linutronix.de

---
kernel/stop_machine.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index b7591261652d..c25ba18274fb 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -36,7 +36,7 @@ struct cpu_stop_done {
struct cpu_stopper {
struct task_struct *thread;

- spinlock_t lock;
+ raw_spinlock_t lock;
bool enabled; /* is this stopper enabled? */
struct list_head works; /* list of pending works */

@@ -78,13 +78,13 @@ static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
unsigned long flags;
bool enabled;

- spin_lock_irqsave(&stopper->lock, flags);
+ raw_spin_lock_irqsave(&stopper->lock, flags);
enabled = stopper->enabled;
if (enabled)
__cpu_stop_queue_work(stopper, work);
else if (work->done)
cpu_stop_signal_done(work->done);
- spin_unlock_irqrestore(&stopper->lock, flags);
+ raw_spin_unlock_irqrestore(&stopper->lock, flags);

return enabled;
}
@@ -231,8 +231,8 @@ static int cpu_stop_queue_two_works(int cpu1, struct cpu_stop_work *work1,
struct cpu_stopper *stopper2 = per_cpu_ptr(&cpu_stopper, cpu2);
int err;
retry:
- spin_lock_irq(&stopper1->lock);
- spin_lock_nested(&stopper2->lock, SINGLE_DEPTH_NESTING);
+ raw_spin_lock_irq(&stopper1->lock);
+ raw_spin_lock_nested(&stopper2->lock, SINGLE_DEPTH_NESTING);

err = -ENOENT;
if (!stopper1->enabled || !stopper2->enabled)
@@ -255,8 +255,8 @@ retry:
__cpu_stop_queue_work(stopper1, work1);
__cpu_stop_queue_work(stopper2, work2);
unlock:
- spin_unlock(&stopper2->lock);
- spin_unlock_irq(&stopper1->lock);
+ raw_spin_unlock(&stopper2->lock);
+ raw_spin_unlock_irq(&stopper1->lock);

if (unlikely(err == -EDEADLK)) {
while (stop_cpus_in_progress)
@@ -448,9 +448,9 @@ static int cpu_stop_should_run(unsigned int cpu)
unsigned long flags;
int run;

- spin_lock_irqsave(&stopper->lock, flags);
+ raw_spin_lock_irqsave(&stopper->lock, flags);
run = !list_empty(&stopper->works);
- spin_unlock_irqrestore(&stopper->lock, flags);
+ raw_spin_unlock_irqrestore(&stopper->lock, flags);
return run;
}

@@ -461,13 +461,13 @@ static void cpu_stopper_thread(unsigned int cpu)

repeat:
work = NULL;
- spin_lock_irq(&stopper->lock);
+ raw_spin_lock_irq(&stopper->lock);
if (!list_empty(&stopper->works)) {
work = list_first_entry(&stopper->works,
struct cpu_stop_work, list);
list_del_init(&work->list);
}
- spin_unlock_irq(&stopper->lock);
+ raw_spin_unlock_irq(&stopper->lock);

if (work) {
cpu_stop_fn_t fn = work->fn;
@@ -541,7 +541,7 @@ static int __init cpu_stop_init(void)
for_each_possible_cpu(cpu) {
struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);

- spin_lock_init(&stopper->lock);
+ raw_spin_lock_init(&stopper->lock);
INIT_LIST_HEAD(&stopper->works);
}