[TIPC]: Optimize stream send routine to avoid fragmentation

This patch enhances TIPC's stream socket send routine so that
it avoids transmitting data in chunks that require fragmentation
and reassembly, thereby improving performance at both the
sending and receiving ends of the connection.

The "maximum packet size" hint that records MTU info allows
the socket to decide how big a chunk it should send; in the
event that the hint has become stale, fragmentation may still
occur, but the data will be passed correctly and the hint will
be updated in time for the following send.  Note: The 66060 byte
pseudo-MTU used for intra-node connections requires the send
routine to perform an additional check to ensure it does not
exceed TIPC"s limit of 66000 bytes of user data per chunk.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Jon Paul Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 8 deletions

diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index ac7f2aacc77b..4a8f37f48764 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -607,23 +607,24 @@ exit:
 static int send_stream(struct kiocb *iocb, struct socket *sock,
                        struct msghdr *m, size_t total_len)
 {
+        struct tipc_port *tport;
         struct msghdr my_msg;
         struct iovec my_iov;
         struct iovec *curr_iov;
         int curr_iovlen;
         char __user *curr_start;
+        u32 hdr_size;
         int curr_left;
         int bytes_to_send;
         int bytes_sent;
         int res;
 
-        if (likely(total_len <= TIPC_MAX_USER_MSG_SIZE))
-                return send_packet(iocb, sock, m, total_len);
-
-        /* Can only send large data streams if already connected */
+        /* Handle special cases where there is no connection */
 
         if (unlikely(sock->state != SS_CONNECTED)) {
-                if (sock->state == SS_DISCONNECTING)
+                if (sock->state == SS_UNCONNECTED)
+                        return send_packet(iocb, sock, m, total_len);
+                else if (sock->state == SS_DISCONNECTING)
                         return -EPIPE;
                 else
                         return -ENOTCONN;
@@ -648,17 +649,25 @@ static int send_stream(struct kiocb *iocb, struct socket *sock,
         my_msg.msg_name = NULL;
         bytes_sent = 0;
 
+        tport = tipc_sk(sock->sk)->p;
+        hdr_size = msg_hdr_sz(&tport->phdr);
+
         while (curr_iovlen--) {
                 curr_start = curr_iov->iov_base;
                 curr_left = curr_iov->iov_len;
 
                 while (curr_left) {
-                        bytes_to_send = (curr_left < TIPC_MAX_USER_MSG_SIZE)
-                                ? curr_left : TIPC_MAX_USER_MSG_SIZE;
+                        bytes_to_send = tport->max_pkt - hdr_size;
+                        if (bytes_to_send > TIPC_MAX_USER_MSG_SIZE)
+                                bytes_to_send = TIPC_MAX_USER_MSG_SIZE;
+                        if (curr_left < bytes_to_send)
+                                bytes_to_send = curr_left;
                         my_iov.iov_base = curr_start;
                         my_iov.iov_len = bytes_to_send;
                         if ((res = send_packet(iocb, sock, &my_msg, 0)) < 0) {
-                                return bytes_sent ? bytes_sent : res;
+                                if (bytes_sent != 0)
+                                        res = bytes_sent;
+                                return res;
                         }
                         curr_left -= bytes_to_send;
                         curr_start += bytes_to_send;