mptcp: cleanup mptcp_subflow_discard_data()

There is no need to use the tcp_read_sock(), we can
simply drop the skb. Additionally try to look at the
next buffer for in order data.

This both simplifies the code and avoid unneeded indirect
calls.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 0a602acf1f3daf1e23777a8b3048db4afffa2525..26f5f81f3f4c3c6f5d19bf9a429300ce105be174 100644 (file)
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -355,7 +355,6 @@ int mptcp_is_enabled(struct net *net);
 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
                                     struct mptcp_options_received *mp_opt);
 bool mptcp_subflow_data_available(struct sock *sk);
-int mptcp_subflow_discard_data(struct sock *sk, unsigned int limit);
 void __init mptcp_subflow_init(void);
 
 /* called with sk socket lock held */

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 0b1d73a69dafb2fb70cc04680c59bf8b86088a17..6eb2fc0a8ebbc9dce7d5f9ec0f84da572b0673d1 100644 (file)
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -805,50 +805,22 @@ validate_seq:
        return MAPPING_OK;
 }
 
-static int subflow_read_actor(read_descriptor_t *desc,
-                             struct sk_buff *skb,
-                             unsigned int offset, size_t len)
+static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
+                                      unsigned int limit)
 {
-       size_t copy_len = min(desc->count, len);
-
-       desc->count -= copy_len;
+       struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
+       bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
+       u32 incr;
 
-       pr_debug("flushed %zu bytes, %zu left", copy_len, desc->count);
-       return copy_len;
-}
+       incr = limit >= skb->len ? skb->len + fin : limit;
 
-int mptcp_subflow_discard_data(struct sock *ssk, unsigned int limit)
-{
-       struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
-       u32 map_remaining;
-       size_t delta;
-
-       map_remaining = subflow->map_data_len -
-                       mptcp_subflow_get_map_offset(subflow);
-       delta = min_t(size_t, limit, map_remaining);
-
-       /* discard mapped data */
-       pr_debug("discarding %zu bytes, current map len=%d", delta,
-                map_remaining);
-       if (delta) {
-               read_descriptor_t desc = {
-                       .count = delta,
-               };
-               int ret;
-
-               ret = tcp_read_sock(ssk, &desc, subflow_read_actor);
-               if (ret < 0) {
-                       ssk->sk_err = -ret;
-                       return ret;
-               }
-               if (ret < delta)
-                       return 0;
-               if (delta == map_remaining) {
-                       subflow->data_avail = 0;
-                       subflow->map_valid = 0;
-               }
-       }
-       return 0;
+       pr_debug("discarding=%d len=%d seq=%d", incr, skb->len,
+                subflow->map_subflow_seq);
+       tcp_sk(ssk)->copied_seq += incr;
+       if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
+               sk_eat_skb(ssk, skb);
+       if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
+               subflow->map_valid = 0;
 }
 
 static bool subflow_check_data_avail(struct sock *ssk)
@@ -923,9 +895,7 @@ static bool subflow_check_data_avail(struct sock *ssk)
                /* only accept in-sequence mapping. Old values are spurious
                 * retransmission
                 */
-               if (mptcp_subflow_discard_data(ssk, old_ack - ack_seq))
-                       goto fatal;
-               return false;
+               mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
        }
        return true;