mptcp: fill skb page frag cache outside of mptcp_sendmsg_frag

The mptcp_sendmsg_frag helper contains a loop that will wait on the
subflow sk.

It seems preferrable to only wait in mptcp_sendmsg() when blocking io is
requested.  mptcp_sendmsg already has such a wait loop that is used when
no subflow socket is available for transmission.

This is another preparation patch that makes sure we call
mptcp_sendmsg_frag only if the page frag cache has been refilled.

Followup patch will remove the wait loop from mptcp_sendmsg_frag().

The retransmit worker doesn't need to do this refill as it won't
transmit new mptcp-level data.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 1bdfbca1c23a3d0203d12606fb6196d8a8e5de1c..a11e51222e59f8b5b72a16a1b0ddef7c4296cd33 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -713,6 +713,7 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 {
        int mss_now = 0, size_goal = 0, ret = 0;
        struct mptcp_sock *msk = mptcp_sk(sk);
+       struct page_frag *pfrag;
        struct socket *ssock;
        size_t copied = 0;
        struct sock *ssk;
@@ -741,13 +742,16 @@ fallback:
                return ret >= 0 ? ret + copied : (copied ? copied : ret);
        }
 
+       pfrag = sk_page_frag(sk);
 restart:
        mptcp_clean_una(sk);
 
 wait_for_sndbuf:
        __mptcp_flush_join_list(msk);
        ssk = mptcp_subflow_get_send(msk);
-       while (!sk_stream_memory_free(sk) || !ssk) {
+       while (!sk_stream_memory_free(sk) ||
+              !ssk ||
+              !mptcp_page_frag_refill(ssk, pfrag)) {
                if (ssk) {
                        /* make sure retransmit timer is
                         * running before we wait for memory.
@@ -808,6 +812,7 @@ wait_for_sndbuf:
                        break;
 
                if (!sk_stream_memory_free(ssk) ||
+                   !mptcp_page_frag_refill(ssk, pfrag) ||
                    !mptcp_ext_cache_refill(msk)) {
                        set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
                        tcp_push(ssk, msg->msg_flags, mss_now,