1// SPDX-License-Identifier: GPL-2.0
 2#include <linux/slab.h>
 3#include <linux/spinlock.h>
 4#include <linux/once.h>
 5#include <linux/random.h>
 6#include <linux/module.h>
 7
 8struct once_work {
 9	struct work_struct work;
10	struct static_key_true *key;
11	struct module *module;
12};
13
14static void once_deferred(struct work_struct *w)
15{
16	struct once_work *work;
17
18	work = container_of(w, struct once_work, work);
19	BUG_ON(!static_key_enabled(work->key));
20	static_branch_disable(work->key);
21	module_put(work->module);
22	kfree(work);
23}
24
25static void once_disable_jump(struct static_key_true *key, struct module *mod)
26{
27	struct once_work *w;
28
29	w = kmalloc(sizeof(*w), GFP_ATOMIC);
30	if (!w)
31		return;
32
33	INIT_WORK(&w->work, once_deferred);
34	w->key = key;
35	w->module = mod;
36	__module_get(mod);
37	schedule_work(&w->work);
38}
39
40static DEFINE_SPINLOCK(once_lock);
41
42bool __do_once_start(bool *done, unsigned long *flags)
43	__acquires(once_lock)
44{
45	spin_lock_irqsave(&once_lock, *flags);
46	if (*done) {
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);
53		return false;
54	}
55
56	return true;
57}
58EXPORT_SYMBOL(__do_once_start);
59
60void __do_once_done(bool *done, struct static_key_true *once_key,
61		    unsigned long *flags, struct module *mod)
62	__releases(once_lock)
63{
64	*done = true;
65	spin_unlock_irqrestore(&once_lock, *flags);
66	once_disable_jump(once_key, mod);
67}
68EXPORT_SYMBOL(__do_once_done);
69
70static DEFINE_MUTEX(once_mutex);
71
72bool __do_once_sleepable_start(bool *done)
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
80		 * __do_once_done but return early in the DO_ONCE_SLEEPABLE() macro.
81		 */
82		__acquire(once_mutex);
83		return false;
84	}
85
86	return true;
87}
88EXPORT_SYMBOL(__do_once_sleepable_start);
89
90void __do_once_sleepable_done(bool *done, struct static_key_true *once_key,
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}
98EXPORT_SYMBOL(__do_once_sleepable_done);

 
 1#include <linux/slab.h>
 2#include <linux/spinlock.h>
 3#include <linux/once.h>
 4#include <linux/random.h>
 
 5
 6struct once_work {
 7	struct work_struct work;
 8	struct static_key *key;
 
 9};
10
11static void once_deferred(struct work_struct *w)
12{
13	struct once_work *work;
14
15	work = container_of(w, struct once_work, work);
16	BUG_ON(!static_key_enabled(work->key));
17	static_key_slow_dec(work->key);
 
18	kfree(work);
19}
20
21static void once_disable_jump(struct static_key *key)
22{
23	struct once_work *w;
24
25	w = kmalloc(sizeof(*w), GFP_ATOMIC);
26	if (!w)
27		return;
28
29	INIT_WORK(&w->work, once_deferred);
30	w->key = key;
 
 
31	schedule_work(&w->work);
32}
33
34static DEFINE_SPINLOCK(once_lock);
35
36bool __do_once_start(bool *done, unsigned long *flags)
37	__acquires(once_lock)
38{
39	spin_lock_irqsave(&once_lock, *flags);
40	if (*done) {
41		spin_unlock_irqrestore(&once_lock, *flags);
42		/* Keep sparse happy by restoring an even lock count on
43		 * this lock. In case we return here, we don't call into
44		 * __do_once_done but return early in the DO_ONCE() macro.
45		 */
46		__acquire(once_lock);
47		return false;
48	}
49
50	return true;
51}
52EXPORT_SYMBOL(__do_once_start);
53
54void __do_once_done(bool *done, struct static_key *once_key,
55		    unsigned long *flags)
56	__releases(once_lock)
57{
58	*done = true;
59	spin_unlock_irqrestore(&once_lock, *flags);
60	once_disable_jump(once_key);
61}
62EXPORT_SYMBOL(__do_once_done);