[Qemu-devel] [PATCH v2 1/3] util: remove the obsolete non-blocking connect

[Cao jin]

The non-blocking connect mechanism is obsolete, and it doesn't work well
in inet connection, because it will call getaddrinfo first and getaddrinfo
will blocks on DNS lookups. Since commit e65c67e4 & d984464e, the non-blocking
connect of migration goes through QIOChannel in a different manner(using a
thread), and nobody use this old non-blocking connect anymore.

Any newly written code which needs a non-blocking connect should use the
QIOChannel code, so we can just rip out NonBlockingConnectHandler as a
concept entirely.

Suggested-by: Daniel P. Berrange <address@hidden>
Cc: Daniel P. Berrange <address@hidden>
Cc: Gerd Hoffmann <address@hidden>
Cc: Paolo Bonzini <address@hidden>

Reviewed-by: Daniel P. Berrange <address@hidden>
Signed-off-by: Cao jin <address@hidden>
---
 include/qemu/sockets.h |   7 +--
 io/channel-socket.c    |   2 +-
 net/socket.c           |   2 +-
 util/qemu-sockets.c    | 163 +++++--------------------------------------------
 4 files changed, 19 insertions(+), 155 deletions(-)

diff --git a/include/qemu/sockets.h b/include/qemu/sockets.h
index 9eb2470..9e7c322 100644
--- a/include/qemu/sockets.h
+++ b/include/qemu/sockets.h
@@ -27,10 +27,6 @@ int socket_set_fast_reuse(int fd);
 #define SHUT_RDWR 2
 #endif
 
-/* callback function for nonblocking connect
- * valid fd on success, negative error code on failure
- */
-typedef void NonBlockingConnectHandler(int fd, Error *err, void *opaque);
 
 InetSocketAddress *inet_parse(const char *str, Error **errp);
 int inet_connect(const char *str, Error **errp);
@@ -41,8 +37,7 @@ int unix_listen(const char *path, char *ostr, int olen, Error 
**errp);
 int unix_connect(const char *path, Error **errp);
 
 SocketAddress *socket_parse(const char *str, Error **errp);
-int socket_connect(SocketAddress *addr, Error **errp,
-                   NonBlockingConnectHandler *callback, void *opaque);
+int socket_connect(SocketAddress *addr, Error **errp);
 int socket_listen(SocketAddress *addr, Error **errp);
 void socket_listen_cleanup(int fd, Error **errp);
 int socket_dgram(SocketAddress *remote, SocketAddress *local, Error **errp);
diff --git a/io/channel-socket.c b/io/channel-socket.c
index 196a4f1..6aa0ad2 100644
--- a/io/channel-socket.c
+++ b/io/channel-socket.c
@@ -147,7 +147,7 @@ int qio_channel_socket_connect_sync(QIOChannelSocket *ioc,
     int fd;
 
     trace_qio_channel_socket_connect_sync(ioc, addr);
-    fd = socket_connect(addr, errp, NULL, NULL);
+    fd = socket_connect(addr, errp);
     if (fd < 0) {
         trace_qio_channel_socket_connect_fail(ioc);
         return -1;
diff --git a/net/socket.c b/net/socket.c
index ae6f921..8037b3c 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -541,7 +541,7 @@ static int net_socket_connect_init(NetClientState *peer,
     qemu_set_nonblock(fd);
     connected = 0;
     for(;;) {
-        ret = socket_connect(saddr, &local_error, NULL, NULL);
+        ret = socket_connect(saddr, &local_error);
         if (ret < 0) {
             if (errno == EINTR || errno == EWOULDBLOCK) {
                 /* continue */
diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
index b4314ca..cd4ed55 100644
--- a/util/qemu-sockets.c
+++ b/util/qemu-sockets.c
@@ -239,96 +239,18 @@ listen:
     return slisten;
 }
 
-#ifdef _WIN32
-#define QEMU_SOCKET_RC_INPROGRESS(rc) \
-    ((rc) == -EINPROGRESS || (rc) == -EWOULDBLOCK || (rc) == -WSAEALREADY)
-#else
-#define QEMU_SOCKET_RC_INPROGRESS(rc) \
-    ((rc) == -EINPROGRESS)
-#endif
-
-/* Struct to store connect state for non blocking connect */
-typedef struct ConnectState {
-    int fd;
-    struct addrinfo *addr_list;
-    struct addrinfo *current_addr;
-    NonBlockingConnectHandler *callback;
-    void *opaque;
-} ConnectState;
-
-static int inet_connect_addr(struct addrinfo *addr, bool *in_progress,
-                             ConnectState *connect_state, Error **errp);
-
-static void wait_for_connect(void *opaque)
-{
-    ConnectState *s = opaque;
-    int val = 0, rc = 0;
-    socklen_t valsize = sizeof(val);
-    bool in_progress;
-    Error *err = NULL;
-
-    qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
-
-    do {
-        rc = qemu_getsockopt(s->fd, SOL_SOCKET, SO_ERROR, &val, &valsize);
-    } while (rc == -1 && errno == EINTR);
-
-    /* update rc to contain error */
-    if (!rc && val) {
-        rc = -1;
-        errno = val;
-    }
-
-    /* connect error */
-    if (rc < 0) {
-        error_setg_errno(&err, errno, "Error connecting to socket");
-        closesocket(s->fd);
-        s->fd = rc;
-    }
-
-    /* try to connect to the next address on the list */
-    if (s->current_addr) {
-        while (s->current_addr->ai_next != NULL && s->fd < 0) {
-            s->current_addr = s->current_addr->ai_next;
-            s->fd = inet_connect_addr(s->current_addr, &in_progress, s, NULL);
-            if (s->fd < 0) {
-                error_free(err);
-                err = NULL;
-                error_setg_errno(&err, errno, "Unable to start socket 
connect");
-            }
-            /* connect in progress */
-            if (in_progress) {
-                goto out;
-            }
-        }
-
-        freeaddrinfo(s->addr_list);
-    }
 
-    if (s->callback) {
-        s->callback(s->fd, err, s->opaque);
-    }
-    g_free(s);
-out:
-    error_free(err);
-}
-
-static int inet_connect_addr(struct addrinfo *addr, bool *in_progress,
-                             ConnectState *connect_state, Error **errp)
+static int inet_connect_addr(struct addrinfo *addr, Error **errp)
 {
     int sock, rc;
 
-    *in_progress = false;
-
     sock = qemu_socket(addr->ai_family, addr->ai_socktype, addr->ai_protocol);
     if (sock < 0) {
         error_setg_errno(errp, errno, "Failed to create socket");
         return -1;
     }
     socket_set_fast_reuse(sock);
-    if (connect_state != NULL) {
-        qemu_set_nonblock(sock);
-    }
+
     /* connect to peer */
     do {
         rc = 0;
@@ -337,15 +259,12 @@ static int inet_connect_addr(struct addrinfo *addr, bool 
*in_progress,
         }
     } while (rc == -EINTR);
 
-    if (connect_state != NULL && QEMU_SOCKET_RC_INPROGRESS(rc)) {
-        connect_state->fd = sock;
-        qemu_set_fd_handler(sock, NULL, wait_for_connect, connect_state);
-        *in_progress = true;
-    } else if (rc < 0) {
+    if (rc < 0) {
         error_setg_errno(errp, errno, "Failed to connect socket");
         closesocket(sock);
         return -1;
     }
+
     return sock;
 }
 
@@ -403,43 +322,25 @@ static struct addrinfo 
*inet_parse_connect_saddr(InetSocketAddress *saddr,
  *
  * @saddr: Inet socket address specification
  * @errp: set on error
- * @callback: callback function for non-blocking connect
- * @opaque: opaque for callback function
  *
  * Returns: -1 on error, file descriptor on success.
- *
- * If @callback is non-null, the connect is non-blocking.  If this
- * function succeeds, callback will be called when the connection
- * completes, with the file descriptor on success, or -1 on error.
  */
-static int inet_connect_saddr(InetSocketAddress *saddr, Error **errp,
-                              NonBlockingConnectHandler *callback, void 
*opaque)
+static int inet_connect_saddr(InetSocketAddress *saddr, Error **errp)
 {
     Error *local_err = NULL;
     struct addrinfo *res, *e;
     int sock = -1;
-    bool in_progress;
-    ConnectState *connect_state = NULL;
 
     res = inet_parse_connect_saddr(saddr, errp);
     if (!res) {
         return -1;
     }
 
-    if (callback != NULL) {
-        connect_state = g_malloc0(sizeof(*connect_state));
-        connect_state->addr_list = res;
-        connect_state->callback = callback;
-        connect_state->opaque = opaque;
-    }
-
     for (e = res; e != NULL; e = e->ai_next) {
         error_free(local_err);
         local_err = NULL;
-        if (connect_state != NULL) {
-            connect_state->current_addr = e;
-        }
-        sock = inet_connect_addr(e, &in_progress, connect_state, &local_err);
+
+        sock = inet_connect_addr(e, &local_err);
         if (sock >= 0) {
             break;
         }
@@ -447,16 +348,10 @@ static int inet_connect_saddr(InetSocketAddress *saddr, 
Error **errp,
 
     if (sock < 0) {
         error_propagate(errp, local_err);
-    } else if (in_progress) {
-        /* wait_for_connect() will do the rest */
-        return sock;
-    } else {
-        if (callback) {
-            callback(sock, NULL, opaque);
-        }
     }
-    g_free(connect_state);
+
     freeaddrinfo(res);
+
     return sock;
 }
 
@@ -640,7 +535,7 @@ int inet_connect(const char *str, Error **errp)
 
     addr = inet_parse(str, errp);
     if (addr != NULL) {
-        sock = inet_connect_saddr(addr, errp, NULL, NULL);
+        sock = inet_connect_saddr(addr, errp);
         qapi_free_InetSocketAddress(addr);
     }
     return sock;
@@ -716,11 +611,9 @@ err:
     return -1;
 }
 
-static int unix_connect_saddr(UnixSocketAddress *saddr, Error **errp,
-                              NonBlockingConnectHandler *callback, void 
*opaque)
+static int unix_connect_saddr(UnixSocketAddress *saddr, Error **errp)
 {
     struct sockaddr_un un;
-    ConnectState *connect_state = NULL;
     int sock, rc;
 
     if (saddr->path == NULL) {
@@ -733,12 +626,6 @@ static int unix_connect_saddr(UnixSocketAddress *saddr, 
Error **errp,
         error_setg_errno(errp, errno, "Failed to create socket");
         return -1;
     }
-    if (callback != NULL) {
-        connect_state = g_malloc0(sizeof(*connect_state));
-        connect_state->callback = callback;
-        connect_state->opaque = opaque;
-        qemu_set_nonblock(sock);
-    }
 
     memset(&un, 0, sizeof(un));
     un.sun_family = AF_UNIX;
@@ -752,24 +639,12 @@ static int unix_connect_saddr(UnixSocketAddress *saddr, 
Error **errp,
         }
     } while (rc == -EINTR);
 
-    if (connect_state != NULL && QEMU_SOCKET_RC_INPROGRESS(rc)) {
-        connect_state->fd = sock;
-        qemu_set_fd_handler(sock, NULL, wait_for_connect, connect_state);
-        return sock;
-    } else if (rc >= 0) {
-        /* non blocking socket immediate success, call callback */
-        if (callback != NULL) {
-            callback(sock, NULL, opaque);
-        }
-    }
-
     if (rc < 0) {
         error_setg_errno(errp, -rc, "Failed to connect socket");
         close(sock);
         sock = -1;
     }
 
-    g_free(connect_state);
     return sock;
 }
 
@@ -784,8 +659,7 @@ static int unix_listen_saddr(UnixSocketAddress *saddr,
     return -1;
 }
 
-static int unix_connect_saddr(UnixSocketAddress *saddr, Error **errp,
-                              NonBlockingConnectHandler *callback, void 
*opaque)
+static int unix_connect_saddr(UnixSocketAddress *saddr, Error **errp)
 {
     error_setg(errp, "unix sockets are not available on windows");
     errno = ENOTSUP;
@@ -829,7 +703,7 @@ int unix_connect(const char *path, Error **errp)
 
     saddr = g_new0(UnixSocketAddress, 1);
     saddr->path = g_strdup(path);
-    sock = unix_connect_saddr(saddr, errp, NULL, NULL);
+    sock = unix_connect_saddr(saddr, errp);
     qapi_free_UnixSocketAddress(saddr);
     return sock;
 }
@@ -872,26 +746,21 @@ fail:
     return NULL;
 }
 
-int socket_connect(SocketAddress *addr, Error **errp,
-                   NonBlockingConnectHandler *callback, void *opaque)
+int socket_connect(SocketAddress *addr, Error **errp)
 {
     int fd;
 
     switch (addr->type) {
     case SOCKET_ADDRESS_KIND_INET:
-        fd = inet_connect_saddr(addr->u.inet.data, errp, callback, opaque);
+        fd = inet_connect_saddr(addr->u.inet.data, errp);
         break;
 
     case SOCKET_ADDRESS_KIND_UNIX:
-        fd = unix_connect_saddr(addr->u.q_unix.data, errp, callback, opaque);
+        fd = unix_connect_saddr(addr->u.q_unix.data, errp);
         break;
 
     case SOCKET_ADDRESS_KIND_FD:
         fd = monitor_get_fd(cur_mon, addr->u.fd.data->str, errp);
-        if (fd >= 0 && callback) {
-            qemu_set_nonblock(fd);
-            callback(fd, NULL, opaque);
-        }
         break;
 
     default:
-- 
2.1.0