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author | Jiri Pirko <jpirko@redhat.com> | 2009-04-14 17:33:57 +0200 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-04-14 18:41:15 +0200 |
commit | 72c6a9870f901045f2464c3dc6ee8914bfdc07aa (patch) | |
tree | 8bd683fea5f20b17dab613ed8864c016e7b5d369 /include/linux/rculist.h | |
parent | 6fd9b3a40b82081d9e6490b0d7cd656e9a78a134 (diff) | |
download | linux-stable-72c6a9870f901045f2464c3dc6ee8914bfdc07aa.tar.gz linux-stable-72c6a9870f901045f2464c3dc6ee8914bfdc07aa.tar.bz2 linux-stable-72c6a9870f901045f2464c3dc6ee8914bfdc07aa.zip |
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@redhat.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: dipankar@in.ibm.com
LKML-Reference: <20090414153356.GC3999@psychotron.englab.brq.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux/rculist.h')
-rw-r--r-- | 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 e649bd3f2c97..5710f43bbc9e 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)) /** |