/* * RCU-based infrastructure for lightweight reader-writer locking * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, you can access it online at * http://www.gnu.org/licenses/gpl-2.0.html. * * 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> enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC }; /* Structure to mediate between updaters and fastpath-using readers. */ struct rcu_sync { int gp_state; int gp_count; wait_queue_head_t gp_wait; int cb_state; struct rcu_head cb_head; enum rcu_sync_type gp_type; }; extern void rcu_sync_lockdep_assert(struct rcu_sync *); /** * 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 an RCU read-side critical section whose * flavor matches that of the rcu_sync struture. */ static inline bool rcu_sync_is_idle(struct rcu_sync *rsp) { #ifdef CONFIG_PROVE_RCU rcu_sync_lockdep_assert(rsp); #endif return !rsp->gp_state; /* GP_IDLE */ } extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type); 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, type) { \ .gp_state = 0, \ .gp_count = 0, \ .gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait), \ .cb_state = 0, \ .gp_type = type, \ } #define __DEFINE_RCU_SYNC(name, type) \ struct rcu_sync_struct name = __RCU_SYNC_INITIALIZER(name, type) #define DEFINE_RCU_SYNC(name) \ __DEFINE_RCU_SYNC(name, RCU_SYNC) #define DEFINE_RCU_SCHED_SYNC(name) \ __DEFINE_RCU_SYNC(name, RCU_SCHED_SYNC) #define DEFINE_RCU_BH_SYNC(name) \ __DEFINE_RCU_SYNC(name, RCU_BH_SYNC) #endif /* _LINUX_RCU_SYNC_H_ */