1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_RCUWAIT_H_
3#define _LINUX_RCUWAIT_H_
4
5#include <linux/rcupdate.h>
6#include <linux/sched/signal.h>
7#include <linux/types.h>
8
9#define __RCUWAIT_INITIALIZER(name) \
10 { .task = NULL, }
11
12static inline void rcuwait_init(struct rcuwait *w)
13{
14 w->task = NULL;
15}
16
17/*
18 * Note: this provides no serialization and, just as with waitqueues,
19 * requires care to estimate as to whether or not the wait is active.
20 */
21static inline int rcuwait_active(struct rcuwait *w)
22{
23 return !!rcu_access_pointer(w->task);
24}
25
26extern int rcuwait_wake_up(struct rcuwait *w);
27
28/*
29 * The caller is responsible for locking around rcuwait_wait_event(),
30 * and [prepare_to/finish]_rcuwait() such that writes to @task are
31 * properly serialized.
32 */
33
34static inline void prepare_to_rcuwait(struct rcuwait *w)
35{
36 rcu_assign_pointer(w->task, current);
37}
38
39extern void finish_rcuwait(struct rcuwait *w);
40
41#define ___rcuwait_wait_event(w, condition, state, ret, cmd) \
42({ \
43 long __ret = ret; \
44 prepare_to_rcuwait(w); \
45 for (;;) { \
46 /* \
47 * Implicit barrier (A) pairs with (B) in \
48 * rcuwait_wake_up(). \
49 */ \
50 set_current_state(state); \
51 if (condition) \
52 break; \
53 \
54 if (signal_pending_state(state, current)) { \
55 __ret = -EINTR; \
56 break; \
57 } \
58 \
59 cmd; \
60 } \
61 finish_rcuwait(w); \
62 __ret; \
63})
64
65#define rcuwait_wait_event(w, condition, state) \
66 ___rcuwait_wait_event(w, condition, state, 0, schedule())
67
68#define __rcuwait_wait_event_timeout(w, condition, state, timeout) \
69 ___rcuwait_wait_event(w, ___wait_cond_timeout(condition), \
70 state, timeout, \
71 __ret = schedule_timeout(__ret))
72
73#define rcuwait_wait_event_timeout(w, condition, state, timeout) \
74({ \
75 long __ret = timeout; \
76 if (!___wait_cond_timeout(condition)) \
77 __ret = __rcuwait_wait_event_timeout(w, condition, \
78 state, timeout); \
79 __ret; \
80})
81
82#endif /* _LINUX_RCUWAIT_H_ */
83

source code of linux/include/linux/rcuwait.h