Subject: Re: [PATCH net-next v4 1/6] bonding: simplify and use RCU protection for 3ad xmit path

From: Ding Tianhong <[email-masked]>
Date: Mon, 9 Sep 2013 16:58:29 +0800

On 2013/9/8 14:05, Ding Tianhong wrote:

Hi Veaceslav and Nik:

please take a moment to reveiw the function just modify for bond_XXX_rcu,
and give me some advice. thanks for the help again.:)

+#define bond_first_slave_rcu(bond) \
+   list_first_or_null_rcu(&(bond)->slave_list, struct slave, list);
+#define bond_last_slave_rcu(bond) \
+   ({struct list_head *__slave_list = &(bond)->slave_list; \
+    struct list_head __rcu *__prev = \
+    (*((struct list_head __rcu **)(&(__slave_list)->prev)));\
+    likely(__slave_list != __prev) ? \
+    container_of(__prev, struct slave, list) : NULL;})
+
 #define bond_is_first_slave(bond, pos) ((pos)->list.prev == &(bond)->slave_list)
 #define bond_is_last_slave(bond, pos) ((pos)->list.next == &(bond)->slave_list)

@@ -93,6 +117,29 @@
    (bond_is_first_slave(bond, pos) ? bond_last_slave(bond) : \
                      bond_to_slave((pos)->list.prev))

+/* Since bond_first/last_slave_rcu can return NULL, these can return NULL too */
+#define bond_next_slave_rcu(bond, pos) \
+   ({struct list_head *__slave_list = &(bond)->slave_list; \
+    struct list_head __rcu *__next = list_next_rcu(__slave_list); \
+    struct list_head *__pos_list = &(pos)->list; \
+    struct list_head __rcu *__pos_next = list_next_rcu(__pos_list); \
+    likely(__pos_next != __slave_list) ? \
+    container_of(__pos_next, struct slave, list) : \
+    container_of(__next, struct slave, list); \
+    })
+
+#define bond_prev_slave_rcu(bond, pos) \
+   ({struct list_head *__slave_list = &(bond)->slave_list; \
+    struct list_head __rcu *__prev = \
+    (*((struct list_head __rcu **)(&(__slave_list)->prev)));\
+    struct list_head *__pos_list = &(pos)->list; \
+    struct list_head __rcu *__pos_prev = (__pos_list->prev != LIST_POISON2) ? \
+    (*((struct list_head __rcu **)(&(__pos_list)->prev))) : NULL; \
+    likely(__pos_prev != __slave_list) ? \
+    ((__pos_prev) ? list_entry_rcu(__pos_prev, struct slave, list) : NULL;) : \
+    (list_entry_rcu(__prev, struct slave, list)); \
+    })
+

-#define bond_for_each_slave_from(bond, pos, cnt, start) \
-   for (cnt = 0, pos = start; pos && cnt < (bond)->slave_cnt; \
-        cnt++, pos = bond_next_slave(bond, pos))
-
+#define bond_for_each_slave_from(bond, pos, start) \
+   for (pos = start; pos; (pos = bond_next_slave(bond, pos)) != start ? \
+       (pos) : (pos = NULL))
+
+#define bond_for_each_slave_from_rcu(bond, pos, start) \
+   for ({struct list_head *__start = &(start)->list; \
+        struct list_head *__slave_list = &(bond)->slave_list; \
+        pos = list_entry_rcu(__start, struct slave, list);}; \
+        pos; \
+        {struct list_head __rcu *__next = list_next_rcu(pos->next); \
+        __next != __slave_list ? \
+        __next : __next = list_next_rcu(__next->next); \
+        __next != __start ? \
+        pos = list_entry_rcu(__next, struct slave, list) : \
+        pos = NULL; \
+        })
+

Best regards
Ding

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