net: add a limit parameter to sk_add_backlog()

sk_add_backlog() & sk_rcvqueues_full() hard coded sk_rcvbuf as the
memory limit. We need to make this limit a parameter for TCP use.

No functional change expected in this patch, all callers still using the
old sk_rcvbuf limit.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Cc: Rick Jones <rick.jones2@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sock.h

@@ -709,17 +709,19 @@ static inline void __sk_add_backlog(struct sock *sk, struct sk_buff *skb)
  * Do not take into account this skb truesize,
  * to allow even a single big packet to come.
  */
-static inline bool sk_rcvqueues_full(const struct sock *sk, const struct sk_buff *skb)
+static inline bool sk_rcvqueues_full(const struct sock *sk, const struct sk_buff *skb,
+				     unsigned int limit)
 {
 	unsigned int qsize = sk->sk_backlog.len + atomic_read(&sk->sk_rmem_alloc);
 
-	return qsize > sk->sk_rcvbuf;
+	return qsize > limit;
 }
 
 /* The per-socket spinlock must be held here. */
-static inline __must_check int sk_add_backlog(struct sock *sk, struct sk_buff *skb)
+static inline __must_check int sk_add_backlog(struct sock *sk, struct sk_buff *skb,
+					      unsigned int limit)
 {
-	if (sk_rcvqueues_full(sk, skb))
+	if (sk_rcvqueues_full(sk, skb, limit))
 		return -ENOBUFS;
 
 	__sk_add_backlog(sk, skb);

net/core/sock.c

@@ -389,7 +389,7 @@ int sk_receive_skb(struct sock *sk, struct sk_buff *skb, const int nested)
 
 	skb->dev = NULL;
 
-	if (sk_rcvqueues_full(sk, skb)) {
+	if (sk_rcvqueues_full(sk, skb, sk->sk_rcvbuf)) {
 		atomic_inc(&sk->sk_drops);
 		goto discard_and_relse;
 	}
@@ -406,7 +406,7 @@ int sk_receive_skb(struct sock *sk, struct sk_buff *skb, const int nested)
 		rc = sk_backlog_rcv(sk, skb);
 
 		mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_);
-	} else if (sk_add_backlog(sk, skb)) {
+	} else if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) {
 		bh_unlock_sock(sk);
 		atomic_inc(&sk->sk_drops);
 		goto discard_and_relse;

net/ipv4/tcp_ipv4.c

@@ -1752,7 +1752,7 @@ process:
 			if (!tcp_prequeue(sk, skb))
 				ret = tcp_v4_do_rcv(sk, skb);
 		}
-	} else if (unlikely(sk_add_backlog(sk, skb))) {
+	} else if (unlikely(sk_add_backlog(sk, skb, sk->sk_rcvbuf))) {
 		bh_unlock_sock(sk);
 		NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
 		goto discard_and_relse;

net/ipv4/udp.c

@@ -1479,7 +1479,7 @@ int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 		goto drop;
 
 
-	if (sk_rcvqueues_full(sk, skb))
+	if (sk_rcvqueues_full(sk, skb, sk->sk_rcvbuf))
 		goto drop;
 
 	rc = 0;
@@ -1488,7 +1488,7 @@ int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 	bh_lock_sock(sk);
 	if (!sock_owned_by_user(sk))
 		rc = __udp_queue_rcv_skb(sk, skb);
-	else if (sk_add_backlog(sk, skb)) {
+	else if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) {
 		bh_unlock_sock(sk);
 		goto drop;
 	}

net/ipv6/tcp_ipv6.c

@@ -1654,7 +1654,7 @@ process:
 			if (!tcp_prequeue(sk, skb))
 				ret = tcp_v6_do_rcv(sk, skb);
 		}
-	} else if (unlikely(sk_add_backlog(sk, skb))) {
+	} else if (unlikely(sk_add_backlog(sk, skb, sk->sk_rcvbuf))) {
 		bh_unlock_sock(sk);
 		NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
 		goto discard_and_relse;

net/ipv6/udp.c

@@ -611,14 +611,14 @@ static void flush_stack(struct sock **stack, unsigned int count,
 
 		sk = stack[i];
 		if (skb1) {
-			if (sk_rcvqueues_full(sk, skb1)) {
+			if (sk_rcvqueues_full(sk, skb1, sk->sk_rcvbuf)) {
 				kfree_skb(skb1);
 				goto drop;
 			}
 			bh_lock_sock(sk);
 			if (!sock_owned_by_user(sk))
 				udpv6_queue_rcv_skb(sk, skb1);
-			else if (sk_add_backlog(sk, skb1)) {
+			else if (sk_add_backlog(sk, skb1, sk->sk_rcvbuf)) {
 				kfree_skb(skb1);
 				bh_unlock_sock(sk);
 				goto drop;
@@ -790,14 +790,14 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
 
 	/* deliver */
 
-	if (sk_rcvqueues_full(sk, skb)) {
+	if (sk_rcvqueues_full(sk, skb, sk->sk_rcvbuf)) {
 		sock_put(sk);
 		goto discard;
 	}
 	bh_lock_sock(sk);
 	if (!sock_owned_by_user(sk))
 		udpv6_queue_rcv_skb(sk, skb);
-	else if (sk_add_backlog(sk, skb)) {
+	else if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) {
 		atomic_inc(&sk->sk_drops);
 		bh_unlock_sock(sk);
 		sock_put(sk);

net/llc/llc_conn.c

@@ -828,7 +828,7 @@ void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb)
 	else {
 		dprintk("%s: adding to backlog...\n", __func__);
 		llc_set_backlog_type(skb, LLC_PACKET);
-		if (sk_add_backlog(sk, skb))
+		if (sk_add_backlog(sk, skb, sk->sk_rcvbuf))
 			goto drop_unlock;
 	}
 out:

net/sctp/input.c

@@ -342,7 +342,7 @@ int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 		sctp_bh_lock_sock(sk);
 
 		if (sock_owned_by_user(sk)) {
-			if (sk_add_backlog(sk, skb))
+			if (sk_add_backlog(sk, skb, sk->sk_rcvbuf))
 				sctp_chunk_free(chunk);
 			else
 				backloged = 1;
@@ -376,7 +376,7 @@ static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
 	struct sctp_ep_common *rcvr = chunk->rcvr;
 	int ret;
 
-	ret = sk_add_backlog(sk, skb);
+	ret = sk_add_backlog(sk, skb, sk->sk_rcvbuf);
 	if (!ret) {
 		/* Hold the assoc/ep while hanging on the backlog queue.
 		 * This way, we know structures we need will not disappear

net/tipc/socket.c

@@ -1330,7 +1330,7 @@ static u32 dispatch(struct tipc_port *tport, struct sk_buff *buf)
 	if (!sock_owned_by_user(sk)) {
 		res = filter_rcv(sk, buf);
 	} else {
-		if (sk_add_backlog(sk, buf))
+		if (sk_add_backlog(sk, buf, sk->sk_rcvbuf))
 			res = TIPC_ERR_OVERLOAD;
 		else
 			res = TIPC_OK;

net/x25/x25_dev.c

@@ -58,7 +58,7 @@ static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
 		if (!sock_owned_by_user(sk)) {
 			queued = x25_process_rx_frame(sk, skb);
 		} else {
-			queued = !sk_add_backlog(sk, skb);
+			queued = !sk_add_backlog(sk, skb, sk->sk_rcvbuf);
 		}
 		bh_unlock_sock(sk);
 		sock_put(sk);