mptcp: fill skb extension 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 a preparation patch that makes sure we call
mptcp_sendmsg_frag only if a skb extension has been allocated.

Moreover, such allocation currently uses GFP_ATOMIC while it
could use sleeping allocation instead.

Followup patches will remove the wait loop from mptcp_sendmsg_frag()
and will allow to do a sleeping allocation for the extension.

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 e973570..1bdfbca 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -669,6 +669,9 @@ static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
 
        sock_owned_by_me((const struct sock *)msk);
 
+       if (!mptcp_ext_cache_refill(msk))
+               return NULL;
+
        mptcp_for_each_subflow(msk, subflow) {
                struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 
@@ -804,7 +807,8 @@ wait_for_sndbuf:
                if (!tx_ok)
                        break;
 
-               if (!sk_stream_memory_free(ssk)) {
+               if (!sk_stream_memory_free(ssk) ||
+                   !mptcp_ext_cache_refill(msk)) {
                        set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
                        tcp_push(ssk, msg->msg_flags, mss_now,
                                 tcp_sk(ssk)->nonagle, size_goal);
@@ -1158,7 +1162,7 @@ static void mptcp_worker(struct work_struct *work)
 {
        struct mptcp_sock *msk = container_of(work, struct mptcp_sock, work);
        struct sock *ssk, *sk = &msk->sk.icsk_inet.sk;
-       int orig_len, orig_offset, ret, mss_now = 0, size_goal = 0;
+       int orig_len, orig_offset, mss_now = 0, size_goal = 0;
        struct mptcp_data_frag *dfrag;
        u64 orig_write_seq;
        size_t copied = 0;
@@ -1180,6 +1184,9 @@ static void mptcp_worker(struct work_struct *work)
        if (!dfrag)
                goto unlock;
 
+       if (!mptcp_ext_cache_refill(msk))
+               goto reset_unlock;
+
        ssk = mptcp_subflow_get_retrans(msk);
        if (!ssk)
                goto reset_unlock;
@@ -1191,8 +1198,8 @@ static void mptcp_worker(struct work_struct *work)
        orig_offset = dfrag->offset;
        orig_write_seq = dfrag->data_seq;
        while (dfrag->data_len > 0) {
-               ret = mptcp_sendmsg_frag(sk, ssk, &msg, dfrag, &timeo, &mss_now,
-                                        &size_goal);
+               int ret = mptcp_sendmsg_frag(sk, ssk, &msg, dfrag, &timeo,
+                                            &mss_now, &size_goal);
                if (ret < 0)
                        break;
 
@@ -1200,6 +1207,9 @@ static void mptcp_worker(struct work_struct *work)
                copied += ret;
                dfrag->data_len -= ret;
                dfrag->offset += ret;
+
+               if (!mptcp_ext_cache_refill(msk))
+                       break;
        }
        if (copied)
                tcp_push(ssk, msg.msg_flags, mss_now, tcp_sk(ssk)->nonagle,