ipv6: lockless IPV6_MINHOPCOUNT implementation

Add one missing READ_ONCE() annotation in do_ipv6_getsockopt()
and make IPV6_MINHOPCOUNT setsockopt() lockless.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 3b2a34828daab5c666d7b429afa961279739c70b..bbc8a009e05d3de49868e1ccf469a12bc31b8e22 100644 (file)
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -448,6 +448,20 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
                        return -EINVAL;
                WRITE_ONCE(np->frag_size, val);
                return 0;
+       case IPV6_MINHOPCOUNT:
+               if (optlen < sizeof(int))
+                       return -EINVAL;
+               if (val < 0 || val > 255)
+                       return -EINVAL;
+
+               if (val)
+                       static_branch_enable(&ip6_min_hopcount);
+
+               /* tcp_v6_err() and tcp_v6_rcv() might read min_hopcount
+                * while we are changing it.
+                */
+               WRITE_ONCE(np->min_hopcount, val);
+               return 0;
        }
        if (needs_rtnl)
                rtnl_lock();
@@ -947,21 +961,6 @@ done:
                        goto e_inval;
                retv = __ip6_sock_set_addr_preferences(sk, val);
                break;
-       case IPV6_MINHOPCOUNT:
-               if (optlen < sizeof(int))
-                       goto e_inval;
-               if (val < 0 || val > 255)
-                       goto e_inval;
-
-               if (val)
-                       static_branch_enable(&ip6_min_hopcount);
-
-               /* tcp_v6_err() and tcp_v6_rcv() might read min_hopcount
-                * while we are changing it.
-                */
-               WRITE_ONCE(np->min_hopcount, val);
-               retv = 0;
-               break;
        case IPV6_DONTFRAG:
                np->dontfrag = valbool;
                retv = 0;
@@ -1443,7 +1442,7 @@ int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
                break;
 
        case IPV6_MINHOPCOUNT:
-               val = np->min_hopcount;
+               val = READ_ONCE(np->min_hopcount);
                break;
 
        case IPV6_DONTFRAG: