diff options
author | Petko Manolov <petkan@mip-labs.com> | 2015-10-12 18:23:51 +0300 |
---|---|---|
committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-12-04 12:34:32 -0800 |
commit | 7d86dccf28a3ae2f790f399fc82d4c82521fd078 (patch) | |
tree | 4edd2478389ec0b6c31dcae73c62fdc875033004 /include/linux/rculist.h | |
parent | 1658d35ead5d8dd76f2b2d6ad0e32c08d123faa2 (diff) | |
download | linux-stable-7d86dccf28a3ae2f790f399fc82d4c82521fd078.tar.gz linux-stable-7d86dccf28a3ae2f790f399fc82d4c82521fd078.tar.bz2 linux-stable-7d86dccf28a3ae2f790f399fc82d4c82521fd078.zip |
list: Introduces generic list_splice_tail_init_rcu()
The list_splice_init_rcu() can be used as a stack onto which full lists
are pushed, but queue-like behavior is now needed by some security
policies. This requires a list_splice_tail_init_rcu().
This commit therefore supplies a list_splice_tail_init_rcu() by
pulling code common it and to list_splice_init_rcu() into a new
__list_splice_init_rcu() function. This new function is based on the
existing list_splice_init_rcu() implementation.
Signed-off-by: Petko Manolov <petkan@mip-labs.com>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'include/linux/rculist.h')
-rw-r--r-- | include/linux/rculist.h | 69 |
1 files changed, 49 insertions, 20 deletions
diff --git a/include/linux/rculist.h b/include/linux/rculist.h index 5ed540986019..e99d834545b6 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -179,32 +179,31 @@ static inline void list_replace_rcu(struct list_head *old, } /** - * list_splice_init_rcu - splice an RCU-protected list into an existing list. + * __list_splice_init_rcu - join an RCU-protected list into an existing list. * @list: the RCU-protected list to splice - * @head: the place in the list to splice the first list into + * @prev: points to the last element of the existing list + * @next: points to the first element of the existing list * @sync: function to sync: synchronize_rcu(), synchronize_sched(), ... * - * @head can be RCU-read traversed concurrently with this function. + * The list pointed to by @prev and @next can be RCU-read traversed + * concurrently with this function. * * Note that this function blocks. * - * Important note: the caller must take whatever action is necessary to - * prevent any other updates to @head. In principle, it is possible - * to modify the list as soon as sync() begins execution. - * If this sort of thing becomes necessary, an alternative version - * based on call_rcu() could be created. But only if -really- - * needed -- there is no shortage of RCU API members. + * Important note: the caller must take whatever action is necessary to prevent + * any other updates to the existing list. In principle, it is possible to + * modify the list as soon as sync() begins execution. If this sort of thing + * becomes necessary, an alternative version based on call_rcu() could be + * created. But only if -really- needed -- there is no shortage of RCU API + * members. */ -static inline void list_splice_init_rcu(struct list_head *list, - struct list_head *head, - void (*sync)(void)) +static inline void __list_splice_init_rcu(struct list_head *list, + struct list_head *prev, + struct list_head *next, + void (*sync)(void)) { struct list_head *first = list->next; struct list_head *last = list->prev; - struct list_head *at = head->next; - - if (list_empty(list)) - return; /* * "first" and "last" tracking list, so initialize it. RCU readers @@ -231,10 +230,40 @@ static inline void list_splice_init_rcu(struct list_head *list, * this function. */ - last->next = at; - rcu_assign_pointer(list_next_rcu(head), first); - first->prev = head; - at->prev = last; + last->next = next; + rcu_assign_pointer(list_next_rcu(prev), first); + first->prev = prev; + next->prev = last; +} + +/** + * list_splice_init_rcu - splice an RCU-protected list into an existing list, + * designed for stacks. + * @list: the RCU-protected list to splice + * @head: the place in the existing list to splice the first list into + * @sync: function to sync: synchronize_rcu(), synchronize_sched(), ... + */ +static inline void list_splice_init_rcu(struct list_head *list, + struct list_head *head, + void (*sync)(void)) +{ + if (!list_empty(list)) + __list_splice_init_rcu(list, head, head->next, sync); +} + +/** + * list_splice_tail_init_rcu - splice an RCU-protected list into an existing + * list, designed for queues. + * @list: the RCU-protected list to splice + * @head: the place in the existing list to splice the first list into + * @sync: function to sync: synchronize_rcu(), synchronize_sched(), ... + */ +static inline void list_splice_tail_init_rcu(struct list_head *list, + struct list_head *head, + void (*sync)(void)) +{ + if (!list_empty(list)) + __list_splice_init_rcu(list, head->prev, head, sync); } /** |