diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/compiler.h | 16 | ||||
| -rw-r--r-- | include/linux/rculist.h | 10 | ||||
| -rw-r--r-- | include/linux/rcupdate.h | 70 | ||||
| -rw-r--r-- | include/linux/rcutiny.h | 16 | ||||
| -rw-r--r-- | include/linux/rcutree.h | 7 | ||||
| -rw-r--r-- | include/linux/spinlock.h | 2 |
6 files changed, 51 insertions, 70 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 867722591be2..5d66777914db 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -252,6 +252,22 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s #define WRITE_ONCE(x, val) \ ({ typeof(x) __val = (val); __write_once_size(&(x), &__val, sizeof(__val)); __val; }) +/** + * READ_ONCE_CTRL - Read a value heading a control dependency + * @x: The value to be read, heading the control dependency + * + * Control dependencies are tricky. See Documentation/memory-barriers.txt + * for important information on how to use them. Note that in many cases, + * use of smp_load_acquire() will be much simpler. Control dependencies + * should be avoided except on the hottest of hotpaths. + */ +#define READ_ONCE_CTRL(x) \ +({ \ + typeof(x) __val = READ_ONCE(x); \ + smp_read_barrier_depends(); /* Enforce control dependency. */ \ + __val; \ +}) + #endif /* __KERNEL__ */ #endif /* __ASSEMBLY__ */ diff --git a/include/linux/rculist.h b/include/linux/rculist.h index a18b16f1dc0e..17c6b1f84a77 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -29,8 +29,8 @@ */ static inline void INIT_LIST_HEAD_RCU(struct list_head *list) { - ACCESS_ONCE(list->next) = list; - ACCESS_ONCE(list->prev) = list; + WRITE_ONCE(list->next, list); + WRITE_ONCE(list->prev, list); } /* @@ -288,7 +288,7 @@ static inline void list_splice_init_rcu(struct list_head *list, #define list_first_or_null_rcu(ptr, type, member) \ ({ \ struct list_head *__ptr = (ptr); \ - struct list_head *__next = ACCESS_ONCE(__ptr->next); \ + struct list_head *__next = READ_ONCE(__ptr->next); \ likely(__ptr != __next) ? list_entry_rcu(__next, type, member) : NULL; \ }) @@ -549,8 +549,8 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n, */ #define hlist_for_each_entry_from_rcu(pos, member) \ for (; pos; \ - pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\ - typeof(*(pos)), member)) + pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \ + &(pos)->member)), typeof(*(pos)), member)) #endif /* __KERNEL__ */ #endif diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 573a5afd5ed8..03a899aabd17 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -292,10 +292,6 @@ void rcu_sched_qs(void); void rcu_bh_qs(void); void rcu_check_callbacks(int user); struct notifier_block; -void rcu_idle_enter(void); -void rcu_idle_exit(void); -void rcu_irq_enter(void); -void rcu_irq_exit(void); int rcu_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu); @@ -364,8 +360,8 @@ extern struct srcu_struct tasks_rcu_exit_srcu; #define rcu_note_voluntary_context_switch(t) \ do { \ rcu_all_qs(); \ - if (ACCESS_ONCE((t)->rcu_tasks_holdout)) \ - ACCESS_ONCE((t)->rcu_tasks_holdout) = false; \ + if (READ_ONCE((t)->rcu_tasks_holdout)) \ + WRITE_ONCE((t)->rcu_tasks_holdout, false); \ } while (0) #else /* #ifdef CONFIG_TASKS_RCU */ #define TASKS_RCU(x) do { } while (0) @@ -609,7 +605,7 @@ static inline void rcu_preempt_sleep_check(void) #define __rcu_access_pointer(p, space) \ ({ \ - typeof(*p) *_________p1 = (typeof(*p) *__force)ACCESS_ONCE(p); \ + typeof(*p) *_________p1 = (typeof(*p) *__force)READ_ONCE(p); \ rcu_dereference_sparse(p, space); \ ((typeof(*p) __force __kernel *)(_________p1)); \ }) @@ -628,21 +624,6 @@ static inline void rcu_preempt_sleep_check(void) ((typeof(*p) __force __kernel *)(p)); \ }) -#define __rcu_access_index(p, space) \ -({ \ - typeof(p) _________p1 = ACCESS_ONCE(p); \ - rcu_dereference_sparse(p, space); \ - (_________p1); \ -}) -#define __rcu_dereference_index_check(p, c) \ -({ \ - /* Dependency order vs. p above. */ \ - typeof(p) _________p1 = lockless_dereference(p); \ - rcu_lockdep_assert(c, \ - "suspicious rcu_dereference_index_check() usage"); \ - (_________p1); \ -}) - /** * RCU_INITIALIZER() - statically initialize an RCU-protected global variable * @v: The value to statically initialize with. @@ -659,7 +640,7 @@ static inline void rcu_preempt_sleep_check(void) */ #define lockless_dereference(p) \ ({ \ - typeof(p) _________p1 = ACCESS_ONCE(p); \ + typeof(p) _________p1 = READ_ONCE(p); \ smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ (_________p1); \ }) @@ -702,7 +683,7 @@ static inline void rcu_preempt_sleep_check(void) * @p: The pointer to read * * Return the value of the specified RCU-protected pointer, but omit the - * smp_read_barrier_depends() and keep the ACCESS_ONCE(). This is useful + * smp_read_barrier_depends() and keep the READ_ONCE(). This is useful * when the value of this pointer is accessed, but the pointer is not * dereferenced, for example, when testing an RCU-protected pointer against * NULL. Although rcu_access_pointer() may also be used in cases where @@ -787,47 +768,12 @@ static inline void rcu_preempt_sleep_check(void) #define rcu_dereference_raw_notrace(p) __rcu_dereference_check((p), 1, __rcu) /** - * rcu_access_index() - fetch RCU index with no dereferencing - * @p: The index to read - * - * Return the value of the specified RCU-protected index, but omit the - * smp_read_barrier_depends() and keep the ACCESS_ONCE(). This is useful - * when the value of this index is accessed, but the index is not - * dereferenced, for example, when testing an RCU-protected index against - * -1. Although rcu_access_index() may also be used in cases where - * update-side locks prevent the value of the index from changing, you - * should instead use rcu_dereference_index_protected() for this use case. - */ -#define rcu_access_index(p) __rcu_access_index((p), __rcu) - -/** - * rcu_dereference_index_check() - rcu_dereference for indices with debug checking - * @p: The pointer to read, prior to dereferencing - * @c: The conditions under which the dereference will take place - * - * Similar to rcu_dereference_check(), but omits the sparse checking. - * This allows rcu_dereference_index_check() to be used on integers, - * which can then be used as array indices. Attempting to use - * rcu_dereference_check() on an integer will give compiler warnings - * because the sparse address-space mechanism relies on dereferencing - * the RCU-protected pointer. Dereferencing integers is not something - * that even gcc will put up with. - * - * Note that this function does not implicitly check for RCU read-side - * critical sections. If this function gains lots of uses, it might - * make sense to provide versions for each flavor of RCU, but it does - * not make sense as of early 2010. - */ -#define rcu_dereference_index_check(p, c) \ - __rcu_dereference_index_check((p), (c)) - -/** * rcu_dereference_protected() - fetch RCU pointer when updates prevented * @p: The pointer to read, prior to dereferencing * @c: The conditions under which the dereference will take place * * Return the value of the specified RCU-protected pointer, but omit - * both the smp_read_barrier_depends() and the ACCESS_ONCE(). This + * both the smp_read_barrier_depends() and the READ_ONCE(). This * is useful in cases where update-side locks prevent the value of the * pointer from changing. Please note that this primitive does -not- * prevent the compiler from repeating this reference or combining it @@ -1153,13 +1099,13 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) #define kfree_rcu(ptr, rcu_head) \ __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head)) -#if defined(CONFIG_TINY_RCU) || defined(CONFIG_RCU_NOCB_CPU_ALL) +#ifdef CONFIG_TINY_RCU static inline int rcu_needs_cpu(unsigned long *delta_jiffies) { *delta_jiffies = ULONG_MAX; return 0; } -#endif /* #if defined(CONFIG_TINY_RCU) || defined(CONFIG_RCU_NOCB_CPU_ALL) */ +#endif /* #ifdef CONFIG_TINY_RCU */ #if defined(CONFIG_RCU_NOCB_CPU_ALL) static inline bool rcu_is_nocb_cpu(int cpu) { return true; } diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 937edaeb150d..3df6c1ec4e25 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -159,6 +159,22 @@ static inline void rcu_cpu_stall_reset(void) { } +static inline void rcu_idle_enter(void) +{ +} + +static inline void rcu_idle_exit(void) +{ +} + +static inline void rcu_irq_enter(void) +{ +} + +static inline void rcu_irq_exit(void) +{ +} + static inline void exit_rcu(void) { } diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index d2e583a6aaca..3fa4a43ab415 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -31,9 +31,7 @@ #define __LINUX_RCUTREE_H void rcu_note_context_switch(void); -#ifndef CONFIG_RCU_NOCB_CPU_ALL int rcu_needs_cpu(unsigned long *delta_jiffies); -#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */ void rcu_cpu_stall_reset(void); /* @@ -93,6 +91,11 @@ void rcu_force_quiescent_state(void); void rcu_bh_force_quiescent_state(void); void rcu_sched_force_quiescent_state(void); +void rcu_idle_enter(void); +void rcu_idle_exit(void); +void rcu_irq_enter(void); +void rcu_irq_exit(void); + void exit_rcu(void); void rcu_scheduler_starting(void); diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 3e18379dfa6f..0063b24b4f36 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -120,7 +120,7 @@ do { \ /* * Despite its name it doesn't necessarily has to be a full barrier. * It should only guarantee that a STORE before the critical section - * can not be reordered with a LOAD inside this section. + * can not be reordered with LOADs and STOREs inside this section. * spin_lock() is the one-way barrier, this LOAD can not escape out * of the region. So the default implementation simply ensures that * a STORE can not move into the critical section, smp_wmb() should |