On 14/03/12 02:35, Michael Roth wrote:
On Wed, Mar 07, 2012 at 06:48:03AM +0800, Amos Kong wrote:
Introduce tcp_client_start() by moving original code in
tcp_start_outgoing_migration().
Signed-off-by: Amos Kong<akong@xxxxxxxxxx>
---
net.c | 41 +++++++++++++++++++++++++++++++++++++++++
qemu_socket.h | 1 +
2 files changed, 42 insertions(+), 0 deletions(-)
diff --git a/net.c b/net.c
index e90ff23..9afb0d1 100644
--- a/net.c
+++ b/net.c
@@ -127,6 +127,47 @@ int tcp_server_start(const char *str, int *fd)
return ret;
}
+int tcp_client_start(const char *str, int *fd)
+{
...
Hi Michael,
+ *fd = qemu_socket(PF_INET, SOCK_STREAM, 0);
+ if (fd< 0) {
+ perror("socket");
+ return -1;
+ }
+ socket_set_nonblock(*fd);
+
+ for (;;) {
+ ret = connect(*fd, (struct sockaddr *)&saddr, sizeof(saddr));
+ if (ret< 0) {
+ ret = -socket_error();
+ if (ret == -EINPROGRESS) {
+ break;
The previous implementation and your next patch seem to be expecting a break on
-EWOULDBLOCK/-EAGAIN as well. Was the behavior changed on purpose?
In original tcp_start_outgoing_migration():
break: -EINPROGRES
cont : -EINTR or -EWOULDBLOCK
In original net_socket_connect_init():
break: -EINPROGRES or -EWOULDBLOCK
cont : -EINTR
http://www.cs.utah.edu/dept/old/texinfo/glibc-manual-0.02/library_15.html
EWOULDBLOCK
socket has nonblocking mode set, and there are no pending
connections immediately available.
So continue to re-connect if EWOULDBLOCK or EINTR returned by
socket_error() in tcp_client_start()
I'm not
sure what the proper handling is for -EAGAIN: whether a non-blocking connect()
can eventually succeed or not. I suspect that it's not, but that previously we
treated it synonymously with -EINPROGRESS, then eventually got an error via
getsockopt() before failing the migration. If so, we're now changing the
behavior to retry until successful, but given the man page entry I don't
think that's a good idea since you might block indefinitely:
EAGAIN No more free local ports or insufficient
entries in the routing cache. For AF_INET
see the description of
/proc/sys/net/ipv4/ip_local_port_range
ip(7) for information on how to increase
the number of local ports.
We didn't process EAGAIN specially, you mean EINTR ?
+#ifdef _WIN32
+ } else if (ret == -WSAEALREADY || ret == -WSAEINVAL) {
+ break;
+#endif
+ } else if (ret != -EINTR&& ret != -EWOULDBLOCK) {
+ perror("connect");
+ closesocket(*fd);
+ return ret;
-EAGAIN would go this path.
+ }
+ } else {
+ break;
+ }
+ }
+
+ return ret;
+}
+
--
Amos.
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