[PATCH net-next] rtnetlink: RCU-annotate both dimensions of rtnl_msg_handlers

[Jakub Kicinski]

We use rcu_assign_pointer to assign both the table and the entries,
but the entries are not marked as __rcu. This generates sparse
warnings.

Signed-off-by: Jakub Kicinski <k...@kernel.org>
---
 net/core/rtnetlink.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 60917ff4a00b..bb0596c41b3e 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -139,7 +139,7 @@ bool lockdep_rtnl_is_held(void)
 EXPORT_SYMBOL(lockdep_rtnl_is_held);
 #endif /* #ifdef CONFIG_PROVE_LOCKING */
 
-static struct rtnl_link *__rcu *rtnl_msg_handlers[RTNL_FAMILY_MAX + 1];
+static struct rtnl_link __rcu *__rcu *rtnl_msg_handlers[RTNL_FAMILY_MAX + 1];
 
 static inline int rtm_msgindex(int msgtype)
 {
@@ -157,7 +157,7 @@ static inline int rtm_msgindex(int msgtype)
 
 static struct rtnl_link *rtnl_get_link(int protocol, int msgtype)
 {
-       struct rtnl_link **tab;
+       struct rtnl_link __rcu **tab;
 
        if (protocol >= ARRAY_SIZE(rtnl_msg_handlers))
                protocol = PF_UNSPEC;
@@ -166,7 +166,7 @@ static struct rtnl_link *rtnl_get_link(int protocol, int 
msgtype)
        if (!tab)
                tab = rcu_dereference_rtnl(rtnl_msg_handlers[PF_UNSPEC]);
 
-       return tab[msgtype];
+       return rcu_dereference_rtnl(tab[msgtype]);
 }
 
 static int rtnl_register_internal(struct module *owner,
@@ -183,7 +183,7 @@ static int rtnl_register_internal(struct module *owner,
        msgindex = rtm_msgindex(msgtype);
 
        rtnl_lock();
-       tab = rtnl_msg_handlers[protocol];
+       tab = rtnl_dereference(rtnl_msg_handlers[protocol]);
        if (tab == NULL) {
                tab = kcalloc(RTM_NR_MSGTYPES, sizeof(void *), GFP_KERNEL);
                if (!tab)
@@ -286,7 +286,8 @@ void rtnl_register(int protocol, int msgtype,
  */
 int rtnl_unregister(int protocol, int msgtype)
 {
-       struct rtnl_link **tab, *link;
+       struct rtnl_link __rcu **tab;
+       struct rtnl_link *link;
        int msgindex;
 
        BUG_ON(protocol < 0 || protocol > RTNL_FAMILY_MAX);
@@ -299,7 +300,7 @@ int rtnl_unregister(int protocol, int msgtype)
                return -ENOENT;
        }
 
-       link = tab[msgindex];
+       link = rtnl_dereference(tab[msgindex]);
        rcu_assign_pointer(tab[msgindex], NULL);
        rtnl_unlock();
 
@@ -318,20 +319,21 @@ EXPORT_SYMBOL_GPL(rtnl_unregister);
  */
 void rtnl_unregister_all(int protocol)
 {
-       struct rtnl_link **tab, *link;
+       struct rtnl_link __rcu **tab;
+       struct rtnl_link *link;
        int msgindex;
 
        BUG_ON(protocol < 0 || protocol > RTNL_FAMILY_MAX);
 
        rtnl_lock();
-       tab = rtnl_msg_handlers[protocol];
+       tab = rtnl_dereference(rtnl_msg_handlers[protocol]);
        if (!tab) {
                rtnl_unlock();
                return;
        }
        RCU_INIT_POINTER(rtnl_msg_handlers[protocol], NULL);
        for (msgindex = 0; msgindex < RTM_NR_MSGTYPES; msgindex++) {
-               link = tab[msgindex];
+               link = rtnl_dereference(tab[msgindex]);
                if (!link)
                        continue;
 
@@ -3754,7 +3756,7 @@ static int rtnl_dump_all(struct sk_buff *skb, struct 
netlink_callback *cb)
                s_idx = 1;
 
        for (idx = 1; idx <= RTNL_FAMILY_MAX; idx++) {
-               struct rtnl_link **tab;
+               struct rtnl_link __rcu **tab;
                struct rtnl_link *link;
                rtnl_dumpit_func dumpit;
 
@@ -3768,7 +3770,7 @@ static int rtnl_dump_all(struct sk_buff *skb, struct 
netlink_callback *cb)
                if (!tab)
                        continue;
 
-               link = tab[type];
+               link = rcu_dereference_rtnl(tab[type]);
                if (!link)
                        continue;
 
-- 
2.26.2