From 176b159d70cb26b24ce928497ae269b294e503d8 Mon Sep 17 00:00:00 2001

From: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Date: Mon, 20 Aug 2012 10:21:54 +0100

Subject: [PATCH] net: asynchronous send/receive infrastructure for

 net/socket.c

The net/socket.c net client is not truly asynchronous.  This patch

borrows the qemu_set_fd_handler2() code from net/tap.c as the basis for

proper asynchronous send/receive.

Only read packets from the socket when the peer is able to receive.

This avoids needless queuing.

Later patches implement asynchronous send.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

(cherry picked from commit 863f678fba4191f3b695620f41056cb7c124425d)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

---

 net/socket.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++------

 1 file changed, 52 insertions(+), 6 deletions(-)

diff --git a/net/socket.c b/net/socket.c

index c172c24..54e32f0 100644

--- a/net/socket.c

+++ b/net/socket.c

@@ -42,9 +42,51 @@ typedef struct NetSocketState {

     unsigned int packet_len;

     uint8_t buf[4096];

     struct sockaddr_in dgram_dst; /* contains inet host and port destination iff connectionless (SOCK_DGRAM) */

+    IOHandler *send_fn;           /* differs between SOCK_STREAM/SOCK_DGRAM */

+    bool read_poll;               /* waiting to receive data? */

+    bool write_poll;              /* waiting to transmit data? */

 } NetSocketState;

 static void net_socket_accept(void *opaque);

+static void net_socket_writable(void *opaque);

+

+/* Only read packets from socket when peer can receive them */

+static int net_socket_can_send(void *opaque)

+{

+    NetSocketState *s = opaque;

+

+    return qemu_can_send_packet(&s->nc);

+}

+

+static void net_socket_update_fd_handler(NetSocketState *s)

+{

+    qemu_set_fd_handler2(s->fd,

+                         s->read_poll  ? net_socket_can_send : NULL,

+                         s->read_poll  ? s->send_fn : NULL,

+                         s->write_poll ? net_socket_writable : NULL,

+                         s);

+}

+

+static void net_socket_read_poll(NetSocketState *s, bool enable)

+{

+    s->read_poll = enable;

+    net_socket_update_fd_handler(s);

+}

+

+static void net_socket_write_poll(NetSocketState *s, bool enable)

+{

+    s->write_poll = enable;

+    net_socket_update_fd_handler(s);

+}

+

+static void net_socket_writable(void *opaque)

+{

+    NetSocketState *s = opaque;

+

+    net_socket_write_poll(s, false);

+

+    qemu_flush_queued_packets(&s->nc);

+}

 /* XXX: we consider we can send the whole packet without blocking */

 static ssize_t net_socket_receive(NetClientState *nc, const uint8_t *buf, size_t size)

@@ -81,7 +123,8 @@ static void net_socket_send(void *opaque)

     } else if (size == 0) {

         /* end of connection */

     eoc:

-        qemu_set_fd_handler(s->fd, NULL, NULL, NULL);

+        net_socket_read_poll(s, false);

+        net_socket_write_poll(s, false);

         if (s->listen_fd != -1) {

             qemu_set_fd_handler(s->listen_fd, net_socket_accept, NULL, s);

         }

@@ -152,7 +195,8 @@ static void net_socket_send_dgram(void *opaque)

         return;

     if (size == 0) {

         /* end of connection */

-        qemu_set_fd_handler(s->fd, NULL, NULL, NULL);

+        net_socket_read_poll(s, false);

+        net_socket_write_poll(s, false);

         return;

     }

     qemu_send_packet(&s->nc, s->buf, size);

@@ -243,7 +287,8 @@ static void net_socket_cleanup(NetClientState *nc)

 {

     NetSocketState *s = DO_UPCAST(NetSocketState, nc, nc);

     if (s->fd != -1) {

-        qemu_set_fd_handler(s->fd, NULL, NULL, NULL);

+        net_socket_read_poll(s, false);

+        net_socket_write_poll(s, false);

         close(s->fd);

         s->fd = -1;

     }

@@ -314,8 +359,8 @@ static NetSocketState *net_socket_fd_init_dgram(NetClientState *peer,

     s->fd = fd;

     s->listen_fd = -1;

-

-    qemu_set_fd_handler(s->fd, net_socket_send_dgram, NULL, s);

+    s->send_fn = net_socket_send_dgram;

+    net_socket_read_poll(s, true);

     /* mcast: save bound address as dst */

     if (is_connected) {

@@ -332,7 +377,8 @@ err:

 static void net_socket_connect(void *opaque)

 {

     NetSocketState *s = opaque;

-    qemu_set_fd_handler(s->fd, net_socket_send, NULL, s);

+    s->send_fn = net_socket_send;

+    net_socket_read_poll(s, true);

 }

 static NetClientInfo net_socket_info = {