]>
Commit | Line | Data |
---|---|---|
1 | #include <linux/slab.h> | |
2 | #include <linux/spinlock.h> | |
3 | #include <linux/once.h> | |
4 | #include <linux/random.h> | |
5 | ||
6 | struct once_work { | |
7 | struct work_struct work; | |
8 | struct static_key *key; | |
9 | }; | |
10 | ||
11 | static 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 | ||
21 | static 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 | ||
34 | static DEFINE_SPINLOCK(once_lock); | |
35 | ||
36 | bool __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 | } | |
52 | EXPORT_SYMBOL(__do_once_start); | |
53 | ||
54 | void __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 | } | |
62 | EXPORT_SYMBOL(__do_once_done); |