| Oleg Nesterov | cc44ca8 | 2015-08-21 19:42:44 +0200 | [diff] [blame^] | 1 | /* |
| 2 | * RCU-based infrastructure for lightweight reader-writer locking |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation; either version 2 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, you can access it online at |
| 16 | * http://www.gnu.org/licenses/gpl-2.0.html. |
| 17 | * |
| 18 | * Copyright (c) 2015, Red Hat, Inc. |
| 19 | * |
| 20 | * Author: Oleg Nesterov <oleg@redhat.com> |
| 21 | */ |
| 22 | |
| 23 | #ifndef _LINUX_RCU_SYNC_H_ |
| 24 | #define _LINUX_RCU_SYNC_H_ |
| 25 | |
| 26 | #include <linux/wait.h> |
| 27 | #include <linux/rcupdate.h> |
| 28 | |
| 29 | /* Structure to mediate between updaters and fastpath-using readers. */ |
| 30 | struct rcu_sync { |
| 31 | int gp_state; |
| 32 | int gp_count; |
| 33 | wait_queue_head_t gp_wait; |
| 34 | |
| 35 | int cb_state; |
| 36 | struct rcu_head cb_head; |
| 37 | |
| 38 | void (*sync)(void); |
| 39 | void (*call)(struct rcu_head *, void (*)(struct rcu_head *)); |
| 40 | }; |
| 41 | |
| 42 | #define ___RCU_SYNC_INIT(name) \ |
| 43 | .gp_state = 0, \ |
| 44 | .gp_count = 0, \ |
| 45 | .gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait), \ |
| 46 | .cb_state = 0 |
| 47 | |
| 48 | #define __RCU_SCHED_SYNC_INIT(name) { \ |
| 49 | ___RCU_SYNC_INIT(name), \ |
| 50 | .sync = synchronize_sched, \ |
| 51 | .call = call_rcu_sched, \ |
| 52 | } |
| 53 | |
| 54 | #define __RCU_BH_SYNC_INIT(name) { \ |
| 55 | ___RCU_SYNC_INIT(name), \ |
| 56 | .sync = synchronize_rcu_bh, \ |
| 57 | .call = call_rcu_bh, \ |
| 58 | } |
| 59 | |
| 60 | #define __RCU_SYNC_INIT(name) { \ |
| 61 | ___RCU_SYNC_INIT(name), \ |
| 62 | .sync = synchronize_rcu, \ |
| 63 | .call = call_rcu, \ |
| 64 | } |
| 65 | |
| 66 | #define DEFINE_RCU_SCHED_SYNC(name) \ |
| 67 | struct rcu_sync name = __RCU_SCHED_SYNC_INIT(name) |
| 68 | |
| 69 | #define DEFINE_RCU_BH_SYNC(name) \ |
| 70 | struct rcu_sync name = __RCU_BH_SYNC_INIT(name) |
| 71 | |
| 72 | #define DEFINE_RCU_SYNC(name) \ |
| 73 | struct rcu_sync name = __RCU_SYNC_INIT(name) |
| 74 | |
| 75 | /** |
| 76 | * rcu_sync_is_idle() - Are readers permitted to use their fastpaths? |
| 77 | * @rsp: Pointer to rcu_sync structure to use for synchronization |
| 78 | * |
| 79 | * Returns true if readers are permitted to use their fastpaths. |
| 80 | * Must be invoked within an RCU read-side critical section whose |
| 81 | * flavor matches that of the rcu_sync struture. |
| 82 | */ |
| 83 | static inline bool rcu_sync_is_idle(struct rcu_sync *rsp) |
| 84 | { |
| 85 | return !rsp->gp_state; /* GP_IDLE */ |
| 86 | } |
| 87 | |
| 88 | enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC }; |
| 89 | |
| 90 | extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type); |
| 91 | extern void rcu_sync_enter(struct rcu_sync *); |
| 92 | extern void rcu_sync_exit(struct rcu_sync *); |
| 93 | |
| 94 | #endif /* _LINUX_RCU_SYNC_H_ */ |