| /* 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_ */ |