rcuwait.h

 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_ */