projects / mirror_ubuntu-artful-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| e260be67 PM |
1 | /* |
| 2 | * Read-Copy Update mechanism for mutual exclusion (RT implementation) | |
| 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, 2006 | |
| 19 | * | |
| 20 | * Author: Paul McKenney <paulmck@us.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 | * Documentation/RCU | |
| 30 | * | |
| 31 | */ | |
| 32 | ||
| 33 | #ifndef __LINUX_RCUPREEMPT_H | |
| 34 | #define __LINUX_RCUPREEMPT_H | |
| 35 | ||
| e260be67 PM |
36 | #include <linux/cache.h> |
| 37 | #include <linux/spinlock.h> | |
| 38 | #include <linux/threads.h> | |
| ac44021f | 39 | #include <linux/smp.h> |
| e260be67 PM |
40 | #include <linux/cpumask.h> |
| 41 | #include <linux/seqlock.h> | |
| 42 | ||
| a979241c IM |
43 | extern void rcu_qsctr_inc(int cpu); |
| 44 | static inline void rcu_bh_qsctr_inc(int cpu) { } | |
| dd0078f4 SR |
45 | |
| 46 | /* | |
| 47 | * Someone might want to pass call_rcu_bh as a function pointer. | |
| 48 | * So this needs to just be a rename and not a macro function. | |
| 49 | * (no parentheses) | |
| 50 | */ | |
| a979241c | 51 | #define call_rcu_bh call_rcu |
| e260be67 | 52 | |
| 4446a36f PM |
53 | /** |
| 54 | * call_rcu_sched - Queue RCU callback for invocation after sched grace period. | |
| 55 | * @head: structure to be used for queueing the RCU updates. | |
| 56 | * @func: actual update function to be invoked after the grace period | |
| 57 | * | |
| 58 | * The update function will be invoked some time after a full | |
| 59 | * synchronize_sched()-style grace period elapses, in other words after | |
| 60 | * all currently executing preempt-disabled sections of code (including | |
| 61 | * hardirq handlers, NMI handlers, and local_irq_save() blocks) have | |
| 62 | * completed. | |
| 63 | */ | |
| 64 | extern void call_rcu_sched(struct rcu_head *head, | |
| 65 | void (*func)(struct rcu_head *head)); | |
| 66 | ||
| b55ab616 PM |
67 | extern void __rcu_read_lock(void) __acquires(RCU); |
| 68 | extern void __rcu_read_unlock(void) __releases(RCU); | |
| e260be67 PM |
69 | extern int rcu_pending(int cpu); |
| 70 | extern int rcu_needs_cpu(int cpu); | |
| 71 | ||
| 72 | #define __rcu_read_lock_bh() { rcu_read_lock(); local_bh_disable(); } | |
| 73 | #define __rcu_read_unlock_bh() { local_bh_enable(); rcu_read_unlock(); } | |
| 74 | ||
| 75 | extern void __synchronize_sched(void); | |
| 76 | ||
| 77 | extern void __rcu_init(void); | |
| 4446a36f | 78 | extern void rcu_init_sched(void); |
| e260be67 PM |
79 | extern void rcu_check_callbacks(int cpu, int user); |
| 80 | extern void rcu_restart_cpu(int cpu); | |
| 81 | extern long rcu_batches_completed(void); | |
| 82 | ||
| 83 | /* | |
| 84 | * Return the number of RCU batches processed thus far. Useful for debug | |
| 85 | * and statistic. The _bh variant is identifcal to straight RCU | |
| 86 | */ | |
| 87 | static inline long rcu_batches_completed_bh(void) | |
| 88 | { | |
| 89 | return rcu_batches_completed(); | |
| 90 | } | |
| 91 | ||
| 92 | #ifdef CONFIG_RCU_TRACE | |
| 93 | struct rcupreempt_trace; | |
| 94 | extern long *rcupreempt_flipctr(int cpu); | |
| 95 | extern long rcupreempt_data_completed(void); | |
| 96 | extern int rcupreempt_flip_flag(int cpu); | |
| 97 | extern int rcupreempt_mb_flag(int cpu); | |
| 98 | extern char *rcupreempt_try_flip_state_name(void); | |
| 99 | extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu); | |
| 100 | #endif | |
| 101 | ||
| 102 | struct softirq_action; | |
| 103 | ||
| 2232c2d8 | 104 | #ifdef CONFIG_NO_HZ |
| a979241c IM |
105 | extern void rcu_enter_nohz(void); |
| 106 | extern void rcu_exit_nohz(void); | |
| 107 | #else | |
| 108 | # define rcu_enter_nohz() do { } while (0) | |
| 109 | # define rcu_exit_nohz() do { } while (0) | |
| 110 | #endif | |
| 2232c2d8 | 111 | |
| a6826048 PM |
112 | /* |
| 113 | * A context switch is a grace period for rcupreempt synchronize_rcu() | |
| 114 | * only during early boot, before the scheduler has been initialized. | |
| 115 | * So, how the heck do we get a context switch? Well, if the caller | |
| 116 | * invokes synchronize_rcu(), they are willing to accept a context | |
| 117 | * switch, so we simply pretend that one happened. | |
| 118 | * | |
| 119 | * After boot, there might be a blocked or preempted task in an RCU | |
| 120 | * read-side critical section, so we cannot then take the fastpath. | |
| 121 | */ | |
| 122 | static inline int rcu_blocking_is_gp(void) | |
| 123 | { | |
| 124 | return num_online_cpus() == 1 && !rcu_scheduler_active; | |
| 125 | } | |
| 126 | ||
| e260be67 | 127 | #endif /* __LINUX_RCUPREEMPT_H */ |