61 lines
1.4 KiB
C
61 lines
1.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _LINUX_RCUWAIT_H_
|
|
#define _LINUX_RCUWAIT_H_
|
|
|
|
#include <linux/rcupdate.h>
|
|
#include <linux/sched/signal.h>
|
|
|
|
/*
|
|
* rcuwait provides a way of blocking and waking up a single
|
|
* task in an rcu-safe manner.
|
|
*
|
|
* The only time @task is non-nil is when a user is blocked (or
|
|
* checking if it needs to) on a condition, and reset as soon as we
|
|
* know that the condition has succeeded and are awoken.
|
|
*/
|
|
struct rcuwait {
|
|
struct task_struct __rcu *task;
|
|
};
|
|
|
|
#define __RCUWAIT_INITIALIZER(name) \
|
|
{ .task = NULL, }
|
|
|
|
static inline void rcuwait_init(struct rcuwait *w)
|
|
{
|
|
w->task = NULL;
|
|
}
|
|
|
|
extern void rcuwait_wake_up(struct rcuwait *w);
|
|
|
|
/*
|
|
* The caller is responsible for locking around rcuwait_wait_event(),
|
|
* such that writes to @task are properly serialized.
|
|
*/
|
|
#define rcuwait_wait_event(w, condition, state) \
|
|
({ \
|
|
int __ret = 0; \
|
|
rcu_assign_pointer((w)->task, current); \
|
|
for (;;) { \
|
|
/* \
|
|
* Implicit barrier (A) pairs with (B) in \
|
|
* rcuwait_wake_up(). \
|
|
*/ \
|
|
set_current_state(state); \
|
|
if (condition) \
|
|
break; \
|
|
\
|
|
if (signal_pending_state(state, current)) { \
|
|
__ret = -EINTR; \
|
|
break; \
|
|
} \
|
|
\
|
|
schedule(); \
|
|
} \
|
|
\
|
|
WRITE_ONCE((w)->task, NULL); \
|
|
__set_current_state(TASK_RUNNING); \
|
|
__ret; \
|
|
})
|
|
|
|
#endif /* _LINUX_RCUWAIT_H_ */
|