I've run into the situation where I need to use list_first_entry with
rcu-guarded list. This patch introduces this. Also changed
list_for_each_entry_rcu to use new list_entry_rcu instead of list_entry.
Jirka
Signed-off-by: Jiri Pirko <[email protected]>
---
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))
/**
--
1.6.0.6
On Tue, Apr 14, 2009 at 05:33:57PM +0200, Jiri Pirko wrote:
> I've run into the situation where I need to use list_first_entry with
> rcu-guarded list. This patch introduces this. Also changed
> list_for_each_entry_rcu to use new list_entry_rcu instead of list_entry.
>
> Jirka
Looks good -- and very nice list_entry_rcu() primitive!
There are a couple more places where this primitive could be applied.
I would welcome a patch for these as well.
include/linux/sched.h next_task 1986 #define next_task(p) list_entry(rcu_dereference((p)->tasks.next), struct task_struct, tasks)
include/linux/sched.h next_thread 2025 return list_entry(rcu_dereference(p->thread_group.next),
ipc/sem.c exit_sem 1293 un = list_entry(rcu_dereference(ulp->list_proc.next),
Reviewed-by: Paul E. McKenney <[email protected]>
> Signed-off-by: Jiri Pirko <[email protected]>
> ---
> 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))
>
>
> /**
> --
> 1.6.0.6
>
----- "Paul E. McKenney" <[email protected]> wrote:
> There are a couple more places where this primitive could be applied.
> I would welcome a patch for these as well.
>
Ok I will do this once this patch hits the tree.
Jirka
Commit-ID: 72c6a9870f901045f2464c3dc6ee8914bfdc07aa
Gitweb: http://git.kernel.org/tip/72c6a9870f901045f2464c3dc6ee8914bfdc07aa
Author: Jiri Pirko <[email protected]>
AuthorDate: Tue, 14 Apr 2009 17:33:57 +0200
Committer: Ingo Molnar <[email protected]>
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 <[email protected]>
Reviewed-by: Paul E. McKenney <[email protected]>
Cc: [email protected]
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
---
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))
/**
* Jiri Pirko <[email protected]> wrote:
> ----- "Paul E. McKenney" <[email protected]> wrote:
> > There are a couple more places where this primitive could be applied.
> > I would welcome a patch for these as well.
> >
> Ok I will do this once this patch hits the tree.
it has just hit the RCU tree so feel free :)
http://people.redhat.com/mingo/tip.git/README
Ingo
On Tue, Apr 14, 2009 at 12:39:51PM -0400, Jiri Pirko wrote:
> ----- "Paul E. McKenney" <[email protected]> wrote:
> > There are a couple more places where this primitive could be applied.
> > I would welcome a patch for these as well.
> >
> Ok I will do this once this patch hits the tree.
Thank you!!!
Thanx, Paul