Rev 1056 | Details | Compare with Previous | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 422 | giacomo | 1 | /* |
| 2 | * Read-Copy Update mechanism for mutual exclusion |
||
| 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, write to the Free Software |
||
| 16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
||
| 17 | * |
||
| 18 | * Copyright (C) IBM Corporation, 2001 |
||
| 19 | * |
||
| 20 | * Author: Dipankar Sarma <dipankar@in.ibm.com> |
||
| 21 | * |
||
| 22 | * Based on the original work by Paul McKenney <paul.mckenney@us.ibm.com> |
||
| 23 | * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. |
||
| 24 | * Papers: |
||
| 25 | * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf |
||
| 26 | * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001) |
||
| 27 | * |
||
| 28 | * For detailed explanation of Read-Copy Update mechanism see - |
||
| 29 | * http://lse.sourceforge.net/locking/rcupdate.html |
||
| 30 | * |
||
| 31 | */ |
||
| 32 | |||
| 33 | #ifndef __LINUX_RCUPDATE_H |
||
| 34 | #define __LINUX_RCUPDATE_H |
||
| 35 | |||
| 36 | #ifdef __KERNEL__ |
||
| 37 | |||
| 38 | #include <linux/cache.h> |
||
| 39 | #include <linux/list.h> |
||
| 40 | #include <linux/spinlock.h> |
||
| 41 | #include <linux/threads.h> |
||
| 42 | #include <linux/percpu.h> |
||
| 43 | #include <linux/cpumask.h> |
||
| 44 | |||
| 45 | /** |
||
| 46 | * struct rcu_head - callback structure for use with RCU |
||
| 47 | * @list: list_head to queue the update requests |
||
| 48 | * @func: actual update function to call after the grace period. |
||
| 49 | * @arg: argument to be passed to the actual update function. |
||
| 50 | */ |
||
| 51 | struct rcu_head { |
||
| 52 | struct list_head list; |
||
| 53 | void (*func)(void *obj); |
||
| 54 | void *arg; |
||
| 55 | }; |
||
| 56 | |||
| 57 | #define RCU_HEAD_INIT(head) \ |
||
| 58 | { list: LIST_HEAD_INIT(head.list), func: NULL, arg: NULL } |
||
| 59 | #define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT(head) |
||
| 60 | #define INIT_RCU_HEAD(ptr) do { \ |
||
| 61 | INIT_LIST_HEAD(&(ptr)->list); (ptr)->func = NULL; (ptr)->arg = NULL; \ |
||
| 62 | } while (0) |
||
| 63 | |||
| 64 | |||
| 65 | |||
| 66 | /* Control variables for rcupdate callback mechanism. */ |
||
| 67 | struct rcu_ctrlblk { |
||
| 68 | spinlock_t mutex; /* Guard this struct */ |
||
| 69 | long curbatch; /* Current batch number. */ |
||
| 70 | long maxbatch; /* Max requested batch number. */ |
||
| 71 | cpumask_t rcu_cpu_mask; /* CPUs that need to switch in order */ |
||
| 72 | /* for current batch to proceed. */ |
||
| 73 | }; |
||
| 74 | |||
| 75 | /* Is batch a before batch b ? */ |
||
| 76 | static inline int rcu_batch_before(long a, long b) |
||
| 77 | { |
||
| 78 | return (a - b) < 0; |
||
| 79 | } |
||
| 80 | |||
| 81 | /* Is batch a after batch b ? */ |
||
| 82 | static inline int rcu_batch_after(long a, long b) |
||
| 83 | { |
||
| 84 | return (a - b) > 0; |
||
| 85 | } |
||
| 86 | |||
| 87 | /* |
||
| 88 | * Per-CPU data for Read-Copy UPdate. |
||
| 89 | * nxtlist - new callbacks are added here |
||
| 90 | * curlist - current batch for which quiescent cycle started if any |
||
| 91 | */ |
||
| 92 | struct rcu_data { |
||
| 93 | long qsctr; /* User-mode/idle loop etc. */ |
||
| 94 | long last_qsctr; /* value of qsctr at beginning */ |
||
| 95 | /* of rcu grace period */ |
||
| 96 | long batch; /* Batch # for current RCU batch */ |
||
| 97 | struct list_head nxtlist; |
||
| 98 | struct list_head curlist; |
||
| 99 | }; |
||
| 100 | |||
| 101 | DECLARE_PER_CPU(struct rcu_data, rcu_data); |
||
| 102 | extern struct rcu_ctrlblk rcu_ctrlblk; |
||
| 103 | |||
| 104 | #define RCU_qsctr(cpu) (per_cpu(rcu_data, (cpu)).qsctr) |
||
| 105 | #define RCU_last_qsctr(cpu) (per_cpu(rcu_data, (cpu)).last_qsctr) |
||
| 106 | #define RCU_batch(cpu) (per_cpu(rcu_data, (cpu)).batch) |
||
| 107 | #define RCU_nxtlist(cpu) (per_cpu(rcu_data, (cpu)).nxtlist) |
||
| 108 | #define RCU_curlist(cpu) (per_cpu(rcu_data, (cpu)).curlist) |
||
| 109 | |||
| 110 | #define RCU_QSCTR_INVALID 0 |
||
| 111 | |||
| 112 | static inline int rcu_pending(int cpu) |
||
| 113 | { |
||
| 1056 | tullio | 114 | /* |
| 422 | giacomo | 115 | if ((!list_empty(&RCU_curlist(cpu)) && |
| 116 | rcu_batch_before(RCU_batch(cpu), rcu_ctrlblk.curbatch)) || |
||
| 117 | (list_empty(&RCU_curlist(cpu)) && |
||
| 118 | !list_empty(&RCU_nxtlist(cpu))) || |
||
| 119 | cpu_isset(cpu, rcu_ctrlblk.rcu_cpu_mask)) |
||
| 120 | return 1; |
||
| 121 | else |
||
| 122 | return 0; |
||
| 1056 | tullio | 123 | */ |
| 124 | return(1); |
||
| 422 | giacomo | 125 | } |
| 126 | |||
| 127 | #define rcu_read_lock() preempt_disable() |
||
| 128 | #define rcu_read_unlock() preempt_enable() |
||
| 129 | |||
| 130 | extern void rcu_init(void); |
||
| 131 | extern void rcu_check_callbacks(int cpu, int user); |
||
| 132 | |||
| 133 | /* Exported interfaces */ |
||
| 134 | extern void FASTCALL(call_rcu(struct rcu_head *head, |
||
| 135 | void (*func)(void *arg), void *arg)); |
||
| 136 | extern void synchronize_kernel(void); |
||
| 137 | |||
| 138 | #endif /* __KERNEL__ */ |
||
| 139 | #endif /* __LINUX_RCUPDATE_H */ |