seq_file: add RCU versions of new hlist/list iterators (v3)

Many usages of seq_file use RCU protected lists, so non RCU
iterators will not work safely.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 16 insertions, 4 deletions

diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 1bf0f708c4f..701fe9cb552 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -406,6 +406,11 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
                 n->next->pprev = &n->next;
 }
 
+#define __hlist_for_each_rcu(pos, head)                 \
+        for (pos = rcu_dereference((head)->first);      \
+             pos && ({ prefetch(pos->next); 1; });      \
+             pos = rcu_dereference(pos->next))
+
 /**
  * hlist_for_each_entry_rcu - iterate over rcu list of given type
  * @tpos:       the type * to use as a loop cursor.
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index c95bcdc18f4..03c0232b416 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -140,10 +140,17 @@ extern struct list_head *seq_list_next(void *v, struct list_head *head,
  */
 
 extern struct hlist_node *seq_hlist_start(struct hlist_head *head,
-                loff_t pos);
+                                          loff_t pos);
 extern struct hlist_node *seq_hlist_start_head(struct hlist_head *head,
-                loff_t pos);
+                                               loff_t pos);
 extern struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
-                loff_t *ppos);
-
+                                         loff_t *ppos);
+
+extern struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
+                                              loff_t pos);
+extern struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
+                                                   loff_t pos);
+extern struct hlist_node *seq_hlist_next_rcu(void *v,
+                                                   struct hlist_head *head,
+                                                   loff_t *ppos);
 #endif