[linux.git] / lib / once.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/once.h>
#include <linux/random.h>
#include <linux/module.h>

struct once_work {
	struct work_struct work;
	struct static_key_true *key;
	struct module *module;
};

static void once_deferred(struct work_struct *w)
{
	struct once_work *work;

	work = container_of(w, struct once_work, work);
	BUG_ON(!static_key_enabled(work->key));
	static_branch_disable(work->key);
	module_put(work->module);
	kfree(work);
}

static void once_disable_jump(struct static_key_true *key, struct module *mod)
{
	struct once_work *w;

	w = kmalloc(sizeof(*w), GFP_ATOMIC);
	if (!w)
		return;

	INIT_WORK(&w->work, once_deferred);
	w->key = key;
	w->module = mod;
	__module_get(mod);
	schedule_work(&w->work);
}

static DEFINE_SPINLOCK(once_lock);

bool __do_once_start(bool *done, unsigned long *flags)
	__acquires(once_lock)
{
	spin_lock_irqsave(&once_lock, *flags);
	if (*done) {
		spin_unlock_irqrestore(&once_lock, *flags);
		/* Keep sparse happy by restoring an even lock count on
		 * this lock. In case we return here, we don't call into
		 * __do_once_done but return early in the DO_ONCE() macro.
		 */
		__acquire(once_lock);
		return false;
	}

	return true;
}
EXPORT_SYMBOL(__do_once_start);

void __do_once_done(bool *done, struct static_key_true *once_key,
		    unsigned long *flags, struct module *mod)
	__releases(once_lock)
{
	*done = true;
	spin_unlock_irqrestore(&once_lock, *flags);
	once_disable_jump(once_key, mod);
}
EXPORT_SYMBOL(__do_once_done);

static DEFINE_MUTEX(once_mutex);

bool __do_once_sleepable_start(bool *done)
	__acquires(once_mutex)
{
	mutex_lock(&once_mutex);
	if (*done) {
		mutex_unlock(&once_mutex);
		/* Keep sparse happy by restoring an even lock count on
		 * this mutex. In case we return here, we don't call into
		 * __do_once_done but return early in the DO_ONCE_SLEEPABLE() macro.
		 */
		__acquire(once_mutex);
		return false;
	}

	return true;
}
EXPORT_SYMBOL(__do_once_sleepable_start);

void __do_once_sleepable_done(bool *done, struct static_key_true *once_key,
			 struct module *mod)
	__releases(once_mutex)
{
	*done = true;
	mutex_unlock(&once_mutex);
	once_disable_jump(once_key, mod);
}
EXPORT_SYMBOL(__do_once_sleepable_done);
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
46234253 HFS	2	#include <linux/slab.h>
	3	#include <linux/spinlock.h>
	4	#include <linux/once.h>
	5	#include <linux/random.h>
1027b96e	6	#include <linux/module.h>
46234253	7
c90aeb94	8	struct once_work {
46234253	9	struct work_struct work;
cf4c950b	10	struct static_key_true *key;
1027b96e	11	struct module *module;
46234253 HFS	12	};
46234253 HFS	13
c90aeb94	14	static void once_deferred(struct work_struct *w)
46234253	15	{
c90aeb94	16	struct once_work *work;
46234253	17
c90aeb94	18	work = container_of(w, struct once_work, work);
46234253	19	BUG_ON(!static_key_enabled(work->key));
cf4c950b	20	static_branch_disable(work->key);
1027b96e	21	module_put(work->module);
46234253 HFS	22	kfree(work);
	23	}
	24
1027b96e	25	static void once_disable_jump(struct static_key_true key, struct module mod)
46234253	26	{
c90aeb94	27	struct once_work *w;
46234253 HFS	28
	29	w = kmalloc(sizeof(*w), GFP_ATOMIC);
	30	if (!w)
	31	return;
	32
c90aeb94	33	INIT_WORK(&w->work, once_deferred);
46234253	34	w->key = key;
1027b96e KW	35	w->module = mod;
1027b96e KW	36	__module_get(mod);
46234253 HFS	37	schedule_work(&w->work);
	38	}
	39
c90aeb94	40	static DEFINE_SPINLOCK(once_lock);
46234253	41
c90aeb94 HFS	42	bool __do_once_start(bool done, unsigned long flags)
	43	__acquires(once_lock)
	44	{
	45	spin_lock_irqsave(&once_lock, *flags);
46234253	46	if (*done) {
c90aeb94 HFS	47	spin_unlock_irqrestore(&once_lock, *flags);
	48	/* Keep sparse happy by restoring an even lock count on
	49	* this lock. In case we return here, we don't call into
	50	* __do_once_done but return early in the DO_ONCE() macro.
	51	*/
	52	__acquire(once_lock);
46234253 HFS	53	return false;
	54	}
	55
46234253 HFS	56	return true;
46234253 HFS	57	}
c90aeb94 HFS	58	EXPORT_SYMBOL(__do_once_start);
c90aeb94 HFS	59
cf4c950b	60	void __do_once_done(bool done, struct static_key_true once_key,
1027b96e	61	unsigned long flags, struct module mod)
c90aeb94 HFS	62	__releases(once_lock)
	63	{
	64	*done = true;
	65	spin_unlock_irqrestore(&once_lock, *flags);
1027b96e	66	once_disable_jump(once_key, mod);
c90aeb94 HFS	67	}
c90aeb94 HFS	68	EXPORT_SYMBOL(__do_once_done);
62c07983 ED	69
	70	static DEFINE_MUTEX(once_mutex);
	71
2a4187f4	72	bool __do_once_sleepable_start(bool *done)
62c07983 ED	73	__acquires(once_mutex)
	74	{
	75	mutex_lock(&once_mutex);
	76	if (*done) {
	77	mutex_unlock(&once_mutex);
	78	/* Keep sparse happy by restoring an even lock count on
	79	* this mutex. In case we return here, we don't call into
2a4187f4	80	* __do_once_done but return early in the DO_ONCE_SLEEPABLE() macro.
62c07983 ED	81	*/
	82	__acquire(once_mutex);
	83	return false;
	84	}
	85
	86	return true;
	87	}
2a4187f4	88	EXPORT_SYMBOL(__do_once_sleepable_start);
62c07983	89
2a4187f4	90	void __do_once_sleepable_done(bool done, struct static_key_true once_key,
62c07983 ED	91	struct module *mod)
	92	__releases(once_mutex)
	93	{
	94	*done = true;
	95	mutex_unlock(&once_mutex);
	96	once_disable_jump(once_key, mod);
	97	}
2a4187f4	98	EXPORT_SYMBOL(__do_once_sleepable_done);