diff options
Diffstat (limited to 'include/linux/rcupdate.h')
| -rw-r--r-- | include/linux/rcupdate.h | 172 |
1 files changed, 117 insertions, 55 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 65163aa0bb04..4db8bcacc51a 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -48,24 +48,14 @@ #define ulong2long(a) (*(long *)(&(a))) /* Exported common interfaces */ - -#ifdef CONFIG_PREEMPT_RCU void call_rcu(struct rcu_head *head, rcu_callback_t func); -#else /* #ifdef CONFIG_PREEMPT_RCU */ -#define call_rcu call_rcu_sched -#endif /* #else #ifdef CONFIG_PREEMPT_RCU */ - -void call_rcu_bh(struct rcu_head *head, rcu_callback_t func); -void call_rcu_sched(struct rcu_head *head, rcu_callback_t func); -void synchronize_sched(void); void rcu_barrier_tasks(void); +void synchronize_rcu(void); #ifdef CONFIG_PREEMPT_RCU void __rcu_read_lock(void); void __rcu_read_unlock(void); -void rcu_read_unlock_special(struct task_struct *t); -void synchronize_rcu(void); /* * Defined as a macro as it is a very low level header included from @@ -89,11 +79,6 @@ static inline void __rcu_read_unlock(void) preempt_enable(); } -static inline void synchronize_rcu(void) -{ - synchronize_sched(); -} - static inline int rcu_preempt_depth(void) { return 0; @@ -104,8 +89,6 @@ static inline int rcu_preempt_depth(void) /* Internal to kernel */ void rcu_init(void); extern int rcu_scheduler_active __read_mostly; -void rcu_sched_qs(void); -void rcu_bh_qs(void); void rcu_check_callbacks(int user); void rcu_report_dead(unsigned int cpu); void rcutree_migrate_callbacks(int cpu); @@ -136,11 +119,10 @@ static inline void rcu_init_nohz(void) { } * RCU_NONIDLE - Indicate idle-loop code that needs RCU readers * @a: Code that RCU needs to pay attention to. * - * RCU, RCU-bh, and RCU-sched read-side critical sections are forbidden - * in the inner idle loop, that is, between the rcu_idle_enter() and - * the rcu_idle_exit() -- RCU will happily ignore any such read-side - * critical sections. However, things like powertop need tracepoints - * in the inner idle loop. + * RCU read-side critical sections are forbidden in the inner idle loop, + * that is, between the rcu_idle_enter() and the rcu_idle_exit() -- RCU + * will happily ignore any such read-side critical sections. However, + * things like powertop need tracepoints in the inner idle loop. * * This macro provides the way out: RCU_NONIDLE(do_something_with_RCU()) * will tell RCU that it needs to pay attention, invoke its argument @@ -159,29 +141,25 @@ static inline void rcu_init_nohz(void) { } } while (0) /* - * Note a voluntary context switch for RCU-tasks benefit. This is a - * macro rather than an inline function to avoid #include hell. + * Note a quasi-voluntary context switch for RCU-tasks's benefit. + * This is a macro rather than an inline function to avoid #include hell. */ #ifdef CONFIG_TASKS_RCU -#define rcu_note_voluntary_context_switch_lite(t) \ +#define rcu_tasks_qs(t) \ do { \ if (READ_ONCE((t)->rcu_tasks_holdout)) \ WRITE_ONCE((t)->rcu_tasks_holdout, false); \ } while (0) -#define rcu_note_voluntary_context_switch(t) \ - do { \ - rcu_all_qs(); \ - rcu_note_voluntary_context_switch_lite(t); \ - } while (0) +#define rcu_note_voluntary_context_switch(t) rcu_tasks_qs(t) void call_rcu_tasks(struct rcu_head *head, rcu_callback_t func); void synchronize_rcu_tasks(void); void exit_tasks_rcu_start(void); void exit_tasks_rcu_finish(void); #else /* #ifdef CONFIG_TASKS_RCU */ -#define rcu_note_voluntary_context_switch_lite(t) do { } while (0) -#define rcu_note_voluntary_context_switch(t) rcu_all_qs() -#define call_rcu_tasks call_rcu_sched -#define synchronize_rcu_tasks synchronize_sched +#define rcu_tasks_qs(t) do { } while (0) +#define rcu_note_voluntary_context_switch(t) do { } while (0) +#define call_rcu_tasks call_rcu +#define synchronize_rcu_tasks synchronize_rcu static inline void exit_tasks_rcu_start(void) { } static inline void exit_tasks_rcu_finish(void) { } #endif /* #else #ifdef CONFIG_TASKS_RCU */ @@ -195,8 +173,8 @@ static inline void exit_tasks_rcu_finish(void) { } */ #define cond_resched_tasks_rcu_qs() \ do { \ - if (!cond_resched()) \ - rcu_note_voluntary_context_switch_lite(current); \ + rcu_tasks_qs(current); \ + cond_resched(); \ } while (0) /* @@ -326,9 +304,8 @@ static inline void rcu_preempt_sleep_check(void) { } * Helper functions for rcu_dereference_check(), rcu_dereference_protected() * and rcu_assign_pointer(). Some of these could be folded into their * callers, but they are left separate in order to ease introduction of - * multiple flavors of pointers to match the multiple flavors of RCU - * (e.g., __rcu_bh, * __rcu_sched, and __srcu), should this make sense in - * the future. + * multiple pointers markings to match different RCU implementations + * (e.g., __srcu), should this make sense in the future. */ #ifdef __CHECKER__ @@ -567,8 +544,8 @@ static inline void rcu_preempt_sleep_check(void) { } * This is simply an identity function, but it documents where a pointer * is handed off from RCU to some other synchronization mechanism, for * example, reference counting or locking. In C11, it would map to - * kill_dependency(). It could be used as follows: - * `` + * kill_dependency(). It could be used as follows:: + * * rcu_read_lock(); * p = rcu_dereference(gp); * long_lived = is_long_lived(p); @@ -579,7 +556,6 @@ static inline void rcu_preempt_sleep_check(void) { } * p = rcu_pointer_handoff(p); * } * rcu_read_unlock(); - *`` */ #define rcu_pointer_handoff(p) (p) @@ -688,14 +664,9 @@ static inline void rcu_read_unlock(void) /** * rcu_read_lock_bh() - mark the beginning of an RCU-bh critical section * - * This is equivalent of rcu_read_lock(), but to be used when updates - * are being done using call_rcu_bh() or synchronize_rcu_bh(). Since - * both call_rcu_bh() and synchronize_rcu_bh() consider completion of a - * softirq handler to be a quiescent state, a process in RCU read-side - * critical section must be protected by disabling softirqs. Read-side - * critical sections in interrupt context can use just rcu_read_lock(), - * though this should at least be commented to avoid confusing people - * reading the code. + * This is equivalent of rcu_read_lock(), but also disables softirqs. + * Note that anything else that disables softirqs can also serve as + * an RCU read-side critical section. * * Note that rcu_read_lock_bh() and the matching rcu_read_unlock_bh() * must occur in the same context, for example, it is illegal to invoke @@ -728,10 +699,9 @@ static inline void rcu_read_unlock_bh(void) /** * rcu_read_lock_sched() - mark the beginning of a RCU-sched critical section * - * This is equivalent of rcu_read_lock(), but to be used when updates - * are being done using call_rcu_sched() or synchronize_rcu_sched(). - * Read-side critical sections can also be introduced by anything that - * disables preemption, including local_irq_disable() and friends. + * This is equivalent of rcu_read_lock(), but disables preemption. + * Read-side critical sections can also be introduced by anything else + * that disables preemption, including local_irq_disable() and friends. * * Note that rcu_read_lock_sched() and the matching rcu_read_unlock_sched() * must occur in the same context, for example, it is illegal to invoke @@ -887,4 +857,96 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) #endif /* #else #ifdef CONFIG_ARCH_WEAK_RELEASE_ACQUIRE */ +/* Has the specified rcu_head structure been handed to call_rcu()? */ + +/* + * rcu_head_init - Initialize rcu_head for rcu_head_after_call_rcu() + * @rhp: The rcu_head structure to initialize. + * + * If you intend to invoke rcu_head_after_call_rcu() to test whether a + * given rcu_head structure has already been passed to call_rcu(), then + * you must also invoke this rcu_head_init() function on it just after + * allocating that structure. Calls to this function must not race with + * calls to call_rcu(), rcu_head_after_call_rcu(), or callback invocation. + */ +static inline void rcu_head_init(struct rcu_head *rhp) +{ + rhp->func = (rcu_callback_t)~0L; +} + +/* + * rcu_head_after_call_rcu - Has this rcu_head been passed to call_rcu()? + * @rhp: The rcu_head structure to test. + * @func: The function passed to call_rcu() along with @rhp. + * + * Returns @true if the @rhp has been passed to call_rcu() with @func, + * and @false otherwise. Emits a warning in any other case, including + * the case where @rhp has already been invoked after a grace period. + * Calls to this function must not race with callback invocation. One way + * to avoid such races is to enclose the call to rcu_head_after_call_rcu() + * in an RCU read-side critical section that includes a read-side fetch + * of the pointer to the structure containing @rhp. + */ +static inline bool +rcu_head_after_call_rcu(struct rcu_head *rhp, rcu_callback_t f) +{ + if (READ_ONCE(rhp->func) == f) + return true; + WARN_ON_ONCE(READ_ONCE(rhp->func) != (rcu_callback_t)~0L); + return false; +} + + +/* Transitional pre-consolidation compatibility definitions. */ + +static inline void synchronize_rcu_bh(void) +{ + synchronize_rcu(); +} + +static inline void synchronize_rcu_bh_expedited(void) +{ + synchronize_rcu_expedited(); +} + +static inline void call_rcu_bh(struct rcu_head *head, rcu_callback_t func) +{ + call_rcu(head, func); +} + +static inline void rcu_barrier_bh(void) +{ + rcu_barrier(); +} + +static inline void synchronize_sched(void) +{ + synchronize_rcu(); +} + +static inline void synchronize_sched_expedited(void) +{ + synchronize_rcu_expedited(); +} + +static inline void call_rcu_sched(struct rcu_head *head, rcu_callback_t func) +{ + call_rcu(head, func); +} + +static inline void rcu_barrier_sched(void) +{ + rcu_barrier(); +} + +static inline unsigned long get_state_synchronize_sched(void) +{ + return get_state_synchronize_rcu(); +} + +static inline void cond_synchronize_sched(unsigned long oldstate) +{ + cond_synchronize_rcu(oldstate); +} + #endif /* __LINUX_RCUPDATE_H */ |