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From: Julia Cartwright <julia@ni.com>
Date: Fri, 28 Sep 2018 21:03:51 +0000
Subject: [PATCH] kthread: convert worker lock to raw spinlock
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.13-rt10.tar.xz
In order to enable the queuing of kthread work items from hardirq
context even when PREEMPT_RT_FULL is enabled, convert the worker
spin_lock to a raw_spin_lock.
This is only acceptable to do because the work performed under the lock
is well-bounded and minimal.
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Guenter Roeck <linux@roeck-us.net>
Reported-and-tested-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Reported-by: Tim Sander <tim@krieglstein.org>
Signed-off-by: Julia Cartwright <julia@ni.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/kthread.h | 2 +-
kernel/kthread.c | 42 +++++++++++++++++++++---------------------
2 files changed, 22 insertions(+), 22 deletions(-)
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -85,7 +85,7 @@ enum {
struct kthread_worker {
unsigned int flags;
- spinlock_t lock;
+ raw_spinlock_t lock;
struct list_head work_list;
struct list_head delayed_work_list;
struct task_struct *task;
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -599,7 +599,7 @@ void __kthread_init_worker(struct kthrea
struct lock_class_key *key)
{
memset(worker, 0, sizeof(struct kthread_worker));
- spin_lock_init(&worker->lock);
+ raw_spin_lock_init(&worker->lock);
lockdep_set_class_and_name(&worker->lock, key, name);
INIT_LIST_HEAD(&worker->work_list);
INIT_LIST_HEAD(&worker->delayed_work_list);
@@ -641,21 +641,21 @@ int kthread_worker_fn(void *worker_ptr)
if (kthread_should_stop()) {
__set_current_state(TASK_RUNNING);
- spin_lock_irq(&worker->lock);
+ raw_spin_lock_irq(&worker->lock);
worker->task = NULL;
- spin_unlock_irq(&worker->lock);
+ raw_spin_unlock_irq(&worker->lock);
return 0;
}
work = NULL;
- spin_lock_irq(&worker->lock);
+ raw_spin_lock_irq(&worker->lock);
if (!list_empty(&worker->work_list)) {
work = list_first_entry(&worker->work_list,
struct kthread_work, node);
list_del_init(&work->node);
}
worker->current_work = work;
- spin_unlock_irq(&worker->lock);
+ raw_spin_unlock_irq(&worker->lock);
if (work) {
__set_current_state(TASK_RUNNING);
@@ -812,12 +812,12 @@ bool kthread_queue_work(struct kthread_w
bool ret = false;
unsigned long flags;
- spin_lock_irqsave(&worker->lock, flags);
+ raw_spin_lock_irqsave(&worker->lock, flags);
if (!queuing_blocked(worker, work)) {
kthread_insert_work(worker, work, &worker->work_list);
ret = true;
}
- spin_unlock_irqrestore(&worker->lock, flags);
+ raw_spin_unlock_irqrestore(&worker->lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(kthread_queue_work);
@@ -843,7 +843,7 @@ void kthread_delayed_work_timer_fn(struc
if (WARN_ON_ONCE(!worker))
return;
- spin_lock(&worker->lock);
+ raw_spin_lock(&worker->lock);
/* Work must not be used with >1 worker, see kthread_queue_work(). */
WARN_ON_ONCE(work->worker != worker);
@@ -852,7 +852,7 @@ void kthread_delayed_work_timer_fn(struc
list_del_init(&work->node);
kthread_insert_work(worker, work, &worker->work_list);
- spin_unlock(&worker->lock);
+ raw_spin_unlock(&worker->lock);
}
EXPORT_SYMBOL(kthread_delayed_work_timer_fn);
@@ -908,14 +908,14 @@ bool kthread_queue_delayed_work(struct k
unsigned long flags;
bool ret = false;
- spin_lock_irqsave(&worker->lock, flags);
+ raw_spin_lock_irqsave(&worker->lock, flags);
if (!queuing_blocked(worker, work)) {
__kthread_queue_delayed_work(worker, dwork, delay);
ret = true;
}
- spin_unlock_irqrestore(&worker->lock, flags);
+ raw_spin_unlock_irqrestore(&worker->lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(kthread_queue_delayed_work);
@@ -951,7 +951,7 @@ void kthread_flush_work(struct kthread_w
if (!worker)
return;
- spin_lock_irq(&worker->lock);
+ raw_spin_lock_irq(&worker->lock);
/* Work must not be used with >1 worker, see kthread_queue_work(). */
WARN_ON_ONCE(work->worker != worker);
@@ -963,7 +963,7 @@ void kthread_flush_work(struct kthread_w
else
noop = true;
- spin_unlock_irq(&worker->lock);
+ raw_spin_unlock_irq(&worker->lock);
if (!noop)
wait_for_completion(&fwork.done);
@@ -996,9 +996,9 @@ static bool __kthread_cancel_work(struct
* any queuing is blocked by setting the canceling counter.
*/
work->canceling++;
- spin_unlock_irqrestore(&worker->lock, *flags);
+ raw_spin_unlock_irqrestore(&worker->lock, *flags);
del_timer_sync(&dwork->timer);
- spin_lock_irqsave(&worker->lock, *flags);
+ raw_spin_lock_irqsave(&worker->lock, *flags);
work->canceling--;
}
@@ -1045,7 +1045,7 @@ bool kthread_mod_delayed_work(struct kth
unsigned long flags;
int ret = false;
- spin_lock_irqsave(&worker->lock, flags);
+ raw_spin_lock_irqsave(&worker->lock, flags);
/* Do not bother with canceling when never queued. */
if (!work->worker)
@@ -1062,7 +1062,7 @@ bool kthread_mod_delayed_work(struct kth
fast_queue:
__kthread_queue_delayed_work(worker, dwork, delay);
out:
- spin_unlock_irqrestore(&worker->lock, flags);
+ raw_spin_unlock_irqrestore(&worker->lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(kthread_mod_delayed_work);
@@ -1076,7 +1076,7 @@ static bool __kthread_cancel_work_sync(s
if (!worker)
goto out;
- spin_lock_irqsave(&worker->lock, flags);
+ raw_spin_lock_irqsave(&worker->lock, flags);
/* Work must not be used with >1 worker, see kthread_queue_work(). */
WARN_ON_ONCE(work->worker != worker);
@@ -1090,13 +1090,13 @@ static bool __kthread_cancel_work_sync(s
* In the meantime, block any queuing by setting the canceling counter.
*/
work->canceling++;
- spin_unlock_irqrestore(&worker->lock, flags);
+ raw_spin_unlock_irqrestore(&worker->lock, flags);
kthread_flush_work(work);
- spin_lock_irqsave(&worker->lock, flags);
+ raw_spin_lock_irqsave(&worker->lock, flags);
work->canceling--;
out_fast:
- spin_unlock_irqrestore(&worker->lock, flags);
+ raw_spin_unlock_irqrestore(&worker->lock, flags);
out:
return ret;
}
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