2 files changed, 33 insertions, 6 deletions

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 1e6bf995435..5ba398e9030 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -104,6 +104,7 @@ struct nlmsgerr
 #define NETLINK_DROP_MEMBERSHIP 2
 #define NETLINK_PKTINFO         3
 #define NETLINK_BROADCAST_ERROR 4
+#define NETLINK_NO_ENOBUFS      5
 
 struct nl_pktinfo
 {
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index b73d4e61c5a..8b6bbb3032b 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -86,6 +86,7 @@ struct netlink_sock {
 #define NETLINK_KERNEL_SOCKET   0x1
 #define NETLINK_RECV_PKTINFO    0x2
 #define NETLINK_BROADCAST_SEND_ERROR    0x4
+#define NETLINK_RECV_NO_ENOBUFS 0x8
 
 static inline struct netlink_sock *nlk_sk(struct sock *sk)
 {
@@ -717,10 +718,15 @@ static int netlink_getname(struct socket *sock, struct sockaddr *addr,
 
 static void netlink_overrun(struct sock *sk)
 {
-        if (!test_and_set_bit(0, &nlk_sk(sk)->state)) {
-                sk->sk_err = ENOBUFS;
-                sk->sk_error_report(sk);
+        struct netlink_sock *nlk = nlk_sk(sk);
+
+        if (!(nlk->flags & NETLINK_RECV_NO_ENOBUFS)) {
+                if (!test_and_set_bit(0, &nlk_sk(sk)->state)) {
+                        sk->sk_err = ENOBUFS;
+                        sk->sk_error_report(sk);
+                }
         }
+        atomic_inc(&sk->sk_drops);
 }
 
 static struct sock *netlink_getsockbypid(struct sock *ssk, u32 pid)
@@ -1182,6 +1188,15 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,
                         nlk->flags &= ~NETLINK_BROADCAST_SEND_ERROR;
                 err = 0;
                 break;
+        case NETLINK_NO_ENOBUFS:
+                if (val) {
+                        nlk->flags |= NETLINK_RECV_NO_ENOBUFS;
+                        clear_bit(0, &nlk->state);
+                        wake_up_interruptible(&nlk->wait);
+                } else
+                        nlk->flags &= ~NETLINK_RECV_NO_ENOBUFS;
+                err = 0;
+                break;
         default:
                 err = -ENOPROTOOPT;
         }
@@ -1224,6 +1239,16 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname,
                         return -EFAULT;
                 err = 0;
                 break;
+        case NETLINK_NO_ENOBUFS:
+                if (len < sizeof(int))
+                        return -EINVAL;
+                len = sizeof(int);
+                val = nlk->flags & NETLINK_RECV_NO_ENOBUFS ? 1 : 0;
+                if (put_user(len, optlen) ||
+                    put_user(val, optval))
+                        return -EFAULT;
+                err = 0;
+                break;
         default:
                 err = -ENOPROTOOPT;
         }
@@ -1879,12 +1904,12 @@ static int netlink_seq_show(struct seq_file *seq, void *v)
         if (v == SEQ_START_TOKEN)
                 seq_puts(seq,
                          "sk       Eth Pid    Groups   "
-                         "Rmem     Wmem     Dump     Locks\n");
+                         "Rmem     Wmem     Dump     Locks     Drops\n");
         else {
                 struct sock *s = v;
                 struct netlink_sock *nlk = nlk_sk(s);
 
-                seq_printf(seq, "%p %-3d %-6d %08x %-8d %-8d %p %d\n",
+                seq_printf(seq, "%p %-3d %-6d %08x %-8d %-8d %p %-8d %-8d\n",
                            s,
                            s->sk_protocol,
                            nlk->pid,
@@ -1892,7 +1917,8 @@ static int netlink_seq_show(struct seq_file *seq, void *v)
                            atomic_read(&s->sk_rmem_alloc),
                            atomic_read(&s->sk_wmem_alloc),
                            nlk->cb,
-                           atomic_read(&s->sk_refcnt)
+                           atomic_read(&s->sk_refcnt),
+                           atomic_read(&s->sk_drops)
                         );
 
         }