tcp_metrics: fix wrong lockdep annotations

Changes in tcp_metric hash table are protected by tcp_metrics_lock
only, not by genl_mutex

While we are at it use deref_locked() instead of rcu_dereference()
in tcp_new() to avoid unnecessary barrier, as we hold tcp_metrics_lock
as well.

Reported-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 098a697b497e ("tcp_metrics: Use a single hash table for all network namespaces.")
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 12 deletions

diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
index 366728cbee4a..5bef3513af77 100644
--- a/net/ipv4/tcp_metrics.c
+++ b/net/ipv4/tcp_metrics.c
@@ -152,6 +152,9 @@ static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst
 #define TCP_METRICS_RECLAIM_DEPTH       5
 #define TCP_METRICS_RECLAIM_PTR         (struct tcp_metrics_block *) 0x1UL
 
+#define deref_locked(p) \
+        rcu_dereference_protected(p, lockdep_is_held(&tcp_metrics_lock))
+
 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
                                           struct inetpeer_addr *saddr,
                                           struct inetpeer_addr *daddr,
@@ -180,9 +183,9 @@ static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
         if (unlikely(reclaim)) {
                 struct tcp_metrics_block *oldest;
 
-                oldest = rcu_dereference(tcp_metrics_hash[hash].chain);
-                for (tm = rcu_dereference(oldest->tcpm_next); tm;
-                     tm = rcu_dereference(tm->tcpm_next)) {
+                oldest = deref_locked(tcp_metrics_hash[hash].chain);
+                for (tm = deref_locked(oldest->tcpm_next); tm;
+                     tm = deref_locked(tm->tcpm_next)) {
                         if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
                                 oldest = tm;
                 }
@@ -1040,12 +1043,6 @@ out_free:
         return ret;
 }
 
-#define deref_locked_genl(p)    \
-        rcu_dereference_protected(p, lockdep_genl_is_held() && \
-                                     lockdep_is_held(&tcp_metrics_lock))
-
-#define deref_genl(p)   rcu_dereference_protected(p, lockdep_genl_is_held())
-
 static void tcp_metrics_flush_all(struct net *net)
 {
         unsigned int max_rows = 1U << tcp_metrics_hash_log;
@@ -1057,8 +1054,7 @@ static void tcp_metrics_flush_all(struct net *net)
                 struct tcp_metrics_block __rcu **pp;
                 spin_lock_bh(&tcp_metrics_lock);
                 pp = &hb->chain;
-                for (tm = deref_locked_genl(*pp); tm;
-                     tm = deref_locked_genl(*pp)) {
+                for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
                         if (net_eq(tm_net(tm), net)) {
                                 *pp = tm->tcpm_next;
                                 kfree_rcu(tm, rcu_head);
@@ -1097,7 +1093,7 @@ static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
         hb = tcp_metrics_hash + hash;
         pp = &hb->chain;
         spin_lock_bh(&tcp_metrics_lock);
-        for (tm = deref_locked_genl(*pp); tm; tm = deref_locked_genl(*pp)) {
+        for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
                     net_eq(tm_net(tm), net)) {