diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/list.h | 27 | ||||
| -rw-r--r-- | include/linux/rcupdate.h | 16 |
2 files changed, 30 insertions, 13 deletions
diff --git a/include/linux/list.h b/include/linux/list.h index 33b863bcb7b9..4de68939e495 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -420,11 +420,11 @@ static inline void list_splice_init(struct list_head *list, */ #define list_for_each_rcu(pos, head) \ for (pos = (head)->next, prefetch(pos->next); pos != (head); \ - pos = pos->next, ({ smp_read_barrier_depends(); 0;}), prefetch(pos->next)) + pos = rcu_dereference(pos->next), prefetch(pos->next)) #define __list_for_each_rcu(pos, head) \ for (pos = (head)->next; pos != (head); \ - pos = pos->next, ({ smp_read_barrier_depends(); 0;})) + pos = rcu_dereference(pos->next)) /** * list_for_each_safe_rcu - iterate over an rcu-protected list safe @@ -439,7 +439,7 @@ static inline void list_splice_init(struct list_head *list, */ #define list_for_each_safe_rcu(pos, n, head) \ for (pos = (head)->next, n = pos->next; pos != (head); \ - pos = n, ({ smp_read_barrier_depends(); 0;}), n = pos->next) + pos = rcu_dereference(n), n = pos->next) /** * list_for_each_entry_rcu - iterate over rcu list of given type @@ -455,8 +455,8 @@ static inline void list_splice_init(struct list_head *list, for (pos = list_entry((head)->next, typeof(*pos), member), \ prefetch(pos->member.next); \ &pos->member != (head); \ - pos = list_entry(pos->member.next, typeof(*pos), member), \ - ({ smp_read_barrier_depends(); 0;}), \ + pos = rcu_dereference(list_entry(pos->member.next, \ + typeof(*pos), member)), \ prefetch(pos->member.next)) @@ -472,7 +472,7 @@ static inline void list_splice_init(struct list_head *list, */ #define list_for_each_continue_rcu(pos, head) \ for ((pos) = (pos)->next, prefetch((pos)->next); (pos) != (head); \ - (pos) = (pos)->next, ({ smp_read_barrier_depends(); 0;}), prefetch((pos)->next)) + (pos) = rcu_dereference((pos)->next), prefetch((pos)->next)) /* * Double linked lists with a single pointer list head. @@ -578,12 +578,9 @@ static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h) * or hlist_del_rcu(), running on this same list. * However, it is perfectly legal to run concurrently with * the _rcu list-traversal primitives, such as - * hlist_for_each_entry(), but only if smp_read_barrier_depends() - * is used to prevent memory-consistency problems on Alpha CPUs. - * Regardless of the type of CPU, the list-traversal primitive - * must be guarded by rcu_read_lock(). - * - * OK, so why don't we have an hlist_for_each_entry_rcu()??? + * hlist_for_each_rcu(), used to prevent memory-consistency + * problems on Alpha CPUs. Regardless of the type of CPU, the + * list-traversal primitive must be guarded by rcu_read_lock(). */ static inline void hlist_add_head_rcu(struct hlist_node *n, struct hlist_head *h) @@ -628,6 +625,10 @@ static inline void hlist_add_after(struct hlist_node *n, for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \ pos = n) +#define hlist_for_each_rcu(pos, head) \ + for ((pos) = (head)->first; pos && ({ prefetch((pos)->next); 1; }); \ + (pos) = rcu_dereference((pos)->next)) + /** * hlist_for_each_entry - iterate over list of given type * @tpos: the type * to use as a loop counter. @@ -693,7 +694,7 @@ static inline void hlist_add_after(struct hlist_node *n, for (pos = (head)->first; \ pos && ({ prefetch(pos->next); 1;}) && \ ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \ - pos = pos->next, ({ smp_read_barrier_depends(); 0; }) ) + pos = rcu_dereference(pos->next)) #else #warning "don't include kernel headers in userspace" diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 32a8893a3cdd..b12bdd9d8f6d 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -222,6 +222,22 @@ static inline int rcu_pending(int cpu) */ #define rcu_read_unlock_bh() local_bh_enable() +/** + * rcu_dereference - fetch an RCU-protected pointer in an + * RCU read-side critical section. This pointer may later + * be safely dereferenced. + * + * Inserts memory barriers on architectures that require them + * (currently only the Alpha), and, more importantly, documents + * exactly which pointers are protected by RCU. + */ + +#define rcu_dereference(p) ({ \ + typeof(p) _________p1 = p; \ + smp_read_barrier_depends(); \ + (_________p1); \ + }) + extern void rcu_init(void); extern void rcu_check_callbacks(int cpu, int user); extern void rcu_restart_cpu(int cpu); |