diff options
Diffstat (limited to 'include/linux/rcu_sync.h')
| -rw-r--r-- | include/linux/rcu_sync.h | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h new file mode 100644 index 000000000..0027d4c80 --- /dev/null +++ b/include/linux/rcu_sync.h @@ -0,0 +1,54 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * RCU-based infrastructure for lightweight reader-writer locking + * + * Copyright (c) 2015, Red Hat, Inc. + * + * Author: Oleg Nesterov <oleg@redhat.com> + */ + +#ifndef _LINUX_RCU_SYNC_H_ +#define _LINUX_RCU_SYNC_H_ + +#include <linux/wait.h> +#include <linux/rcupdate.h> + +/* Structure to mediate between updaters and fastpath-using readers. */ +struct rcu_sync { + int gp_state; + int gp_count; + wait_queue_head_t gp_wait; + + struct rcu_head cb_head; +}; + +/** + * rcu_sync_is_idle() - Are readers permitted to use their fastpaths? + * @rsp: Pointer to rcu_sync structure to use for synchronization + * + * Returns true if readers are permitted to use their fastpaths. Must be + * invoked within some flavor of RCU read-side critical section. + */ +static inline bool rcu_sync_is_idle(struct rcu_sync *rsp) +{ + RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), + "suspicious rcu_sync_is_idle() usage"); + return !READ_ONCE(rsp->gp_state); /* GP_IDLE */ +} + +extern void rcu_sync_init(struct rcu_sync *); +extern void rcu_sync_enter_start(struct rcu_sync *); +extern void rcu_sync_enter(struct rcu_sync *); +extern void rcu_sync_exit(struct rcu_sync *); +extern void rcu_sync_dtor(struct rcu_sync *); + +#define __RCU_SYNC_INITIALIZER(name) { \ + .gp_state = 0, \ + .gp_count = 0, \ + .gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait), \ + } + +#define DEFINE_RCU_SYNC(name) \ + struct rcu_sync name = __RCU_SYNC_INITIALIZER(name) + +#endif /* _LINUX_RCU_SYNC_H_ */ |