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git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - include/linux/rcuwait.h
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_RCUWAIT_H_
3 #define _LINUX_RCUWAIT_H_
5 #include <linux/rcupdate.h>
6 #include <linux/sched/signal.h>
9 * rcuwait provides a way of blocking and waking up a single
10 * task in an rcu-safe manner.
12 * The only time @task is non-nil is when a user is blocked (or
13 * checking if it needs to) on a condition, and reset as soon as we
14 * know that the condition has succeeded and are awoken.
17 struct task_struct __rcu
*task
;
20 #define __RCUWAIT_INITIALIZER(name) \
23 static inline void rcuwait_init(struct rcuwait
*w
)
29 * Note: this provides no serialization and, just as with waitqueues,
30 * requires care to estimate as to whether or not the wait is active.
32 static inline int rcuwait_active(struct rcuwait
*w
)
34 return !!rcu_access_pointer(w
->task
);
37 extern int rcuwait_wake_up(struct rcuwait
*w
);
40 * The caller is responsible for locking around rcuwait_wait_event(),
41 * and [prepare_to/finish]_rcuwait() such that writes to @task are
42 * properly serialized.
45 static inline void prepare_to_rcuwait(struct rcuwait
*w
)
47 rcu_assign_pointer(w
->task
, current
);
50 static inline void finish_rcuwait(struct rcuwait
*w
)
52 rcu_assign_pointer(w
->task
, NULL
);
53 __set_current_state(TASK_RUNNING
);
56 #define rcuwait_wait_event(w, condition, state) \
59 prepare_to_rcuwait(w); \
62 * Implicit barrier (A) pairs with (B) in \
63 * rcuwait_wake_up(). \
65 set_current_state(state); \
69 if (signal_pending_state(state, current)) { \
80 #endif /* _LINUX_RCUWAIT_H_ */