mptcp: add MSG_PEEK support

This patch adds support for MSG_PEEK flag. Packets are not removed
from the receive_queue if MSG_PEEK set in recv() system call.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Yonglong Li <liyonglong@chinatelecom.cn>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index a996dd5..8bf2199 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1745,10 +1745,10 @@ static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk,
                                struct msghdr *msg,
                                size_t len, int flags)
 {
-       struct sk_buff *skb;
+       struct sk_buff *skb, *tmp;
        int copied = 0;
 
-       while ((skb = skb_peek(&msk->receive_queue)) != NULL) {
+       skb_queue_walk_safe(&msk->receive_queue, skb, tmp) {
                u32 offset = MPTCP_SKB_CB(skb)->offset;
                u32 data_len = skb->len - offset;
                u32 count = min_t(size_t, len - copied, data_len);
@@ -1766,15 +1766,18 @@ static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk,
                copied += count;
 
                if (count < data_len) {
-                       MPTCP_SKB_CB(skb)->offset += count;
+                       if (!(flags & MSG_PEEK))
+                               MPTCP_SKB_CB(skb)->offset += count;
                        break;
                }
 
-               /* we will bulk release the skb memory later */
-               skb->destructor = NULL;
-               msk->rmem_released += skb->truesize;
-               __skb_unlink(skb, &msk->receive_queue);
-               __kfree_skb(skb);
+               if (!(flags & MSG_PEEK)) {
+                       /* we will bulk release the skb memory later */
+                       skb->destructor = NULL;
+                       msk->rmem_released += skb->truesize;
+                       __skb_unlink(skb, &msk->receive_queue);
+                       __kfree_skb(skb);
+               }
 
                if (copied >= len)
                        break;
@@ -2053,7 +2056,8 @@ out_err:
        pr_debug("msk=%p data_ready=%d rx queue empty=%d copied=%d",
                 msk, test_bit(MPTCP_DATA_READY, &msk->flags),
                 skb_queue_empty_lockless(&sk->sk_receive_queue), copied);
-       mptcp_rcv_space_adjust(msk, copied);
+       if (!(flags & MSG_PEEK))
+               mptcp_rcv_space_adjust(msk, copied);
 
        release_sock(sk);
        return copied;