Commit-ID: 72c6a9870f901045f2464c3dc6ee8914bfdc07aa Gitweb: http://git.kernel.org/tip/72c6a9870f901045f2464c3dc6ee8914bfdc07aa Author: Jiri Pirko <jpirko@xxxxxxxxxx> AuthorDate: Tue, 14 Apr 2009 17:33:57 +0200 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Tue, 14 Apr 2009 18:41:15 +0200 rculist.h: introduce list_entry_rcu() and list_first_entry_rcu() I've run into the situation where I need to use list_first_entry with rcu-guarded list. This patch introduces this. Also simplify list_for_each_entry_rcu() to use new list_entry_rcu() instead of list_entry(). Signed-off-by: Jiri Pirko <jpirko@xxxxxxxxxx> Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> Cc: dipankar@xxxxxxxxxx LKML-Reference: <20090414153356.GC3999@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- include/linux/rculist.h | 30 ++++++++++++++++++++++++++++-- 1 files changed, 28 insertions(+), 2 deletions(-) diff --git a/include/linux/rculist.h b/include/linux/rculist.h index e649bd3..5710f43 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -198,6 +198,32 @@ static inline void list_splice_init_rcu(struct list_head *list, at->prev = last; } +/** + * list_entry_rcu - get the struct for this entry + * @ptr: the &struct list_head pointer. + * @type: the type of the struct this is embedded in. + * @member: the name of the list_struct within the struct. + * + * This primitive may safely run concurrently with the _rcu list-mutation + * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). + */ +#define list_entry_rcu(ptr, type, member) \ + container_of(rcu_dereference(ptr), type, member) + +/** + * list_first_entry_rcu - get the first element from a list + * @ptr: the list head to take the element from. + * @type: the type of the struct this is embedded in. + * @member: the name of the list_struct within the struct. + * + * Note, that list is expected to be not empty. + * + * This primitive may safely run concurrently with the _rcu list-mutation + * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). + */ +#define list_first_entry_rcu(ptr, type, member) \ + list_entry_rcu((ptr)->next, type, member) + #define __list_for_each_rcu(pos, head) \ for (pos = rcu_dereference((head)->next); \ pos != (head); \ @@ -214,9 +240,9 @@ static inline void list_splice_init_rcu(struct list_head *list, * as long as the traversal is guarded by rcu_read_lock(). */ #define list_for_each_entry_rcu(pos, head, member) \ - for (pos = list_entry(rcu_dereference((head)->next), typeof(*pos), member); \ + for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \ prefetch(pos->member.next), &pos->member != (head); \ - pos = list_entry(rcu_dereference(pos->member.next), typeof(*pos), member)) + pos = list_entry_rcu(pos->member.next, typeof(*pos), member)) /** -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|