Currently, socket connection in net is realized by an old
mechanism which is non-blocking.

That old mechanism may cause net blocks on DNS lookups and
QEmu has already replaced it with QIOchannel in many features,
such as migration.

Convert it to QIOchannel for net as well.

CC: berrange@redhat.com, pbonzini@redhat.com, jasowang@redhat.com
Signed-off-by: Mao Zhongyi <maozy.fnst@cn.fujitsu.com>
---
The test steps like this:

    $ qemu-system-x86_64 -net nic -net socket,listen=:1234 ~/img/test.img
    $ qemu-system-x86_64 -net nic -net socket,connect=127.0.0.1:1234 ~/img/test.img

No exception.

 net/socket.c | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/net/socket.c b/net/socket.c
index b8c931e..52f9dce 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -33,6 +33,7 @@
 #include "qemu/sockets.h"
 #include "qemu/iov.h"
 #include "qemu/main-loop.h"
+#include "io/channel-socket.h"
 
 typedef struct NetSocketState {
     NetClientState nc;
@@ -525,16 +526,22 @@ typedef struct {
     char *name;
 } socket_connect_data;
 
-static void socket_connect_data_free(socket_connect_data *c)
+static void socket_connect_data_free(void *opaque)
 {
+    socket_connect_data *c = opaque;
+    if (!c) {
+        return;
+    }
+
     qapi_free_SocketAddress(c->saddr);
     g_free(c->model);
     g_free(c->name);
     g_free(c);
 }
 
-static void net_socket_connected(int fd, Error *err, void *opaque)
+static void net_socket_connected(QIOTask *task, void *opaque)
 {
+    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(qio_task_get_source(task));
     socket_connect_data *c = opaque;
     NetSocketState *s;
     char *addr_str = NULL;
@@ -543,13 +550,13 @@ static void net_socket_connected(int fd, Error *err, void *opaque)
     addr_str = socket_address_to_string(c->saddr, &local_error);
     if (addr_str == NULL) {
         error_report_err(local_error);
-        closesocket(fd);
+        closesocket(sioc->fd);
         goto end;
     }
 
-    s = net_socket_fd_init(c->peer, c->model, c->name, fd, true);
+    s = net_socket_fd_init(c->peer, c->model, c->name, sioc->fd, true);
     if (!s) {
-        closesocket(fd);
+        closesocket(sioc->fd);
         goto end;
     }
 
@@ -567,7 +574,7 @@ static int net_socket_connect_init(NetClientState *peer,
                                    const char *host_str)
 {
     socket_connect_data *c = g_new0(socket_connect_data, 1);
-    int fd = -1;
+    QIOChannelSocket *sioc;
     Error *local_error = NULL;
 
     c->peer = peer;
@@ -578,11 +585,12 @@ static int net_socket_connect_init(NetClientState *peer,
         goto err;
     }
 
-    fd = socket_connect(c->saddr, net_socket_connected, c, &local_error);
-    if (fd < 0) {
-        goto err;
-    }
-
+    sioc = qio_channel_socket_new();
+    qio_channel_socket_connect_async(sioc,
+                                     c->saddr,
+                                     net_socket_connected,
+                                     c,
+                                     NULL);
     return 0;
 
 err:
-- 
2.9.3

On Wed, Apr 26, 2017 at 04:04:15PM +0800, Mao Zhongyi wrote:
> Currently, socket connection in net is realized by an old
> mechanism which is non-blocking.
> 
> That old mechanism may cause net blocks on DNS lookups and
> QEmu has already replaced it with QIOchannel in many features,
> such as migration.
> 
> Convert it to QIOchannel for net as well.
> 
> CC: berrange@redhat.com, pbonzini@redhat.com, jasowang@redhat.com
> Signed-off-by: Mao Zhongyi <maozy.fnst@cn.fujitsu.com>
> ---
> The test steps like this:
> 
>     $ qemu-system-x86_64 -net nic -net socket,listen=:1234 ~/img/test.img
>     $ qemu-system-x86_64 -net nic -net socket,connect=127.0.0.1:1234 ~/img/test.img
> 
> No exception.
> 
>  net/socket.c | 30 +++++++++++++++++++-----------
>  1 file changed, 19 insertions(+), 11 deletions(-)
> 
> diff --git a/net/socket.c b/net/socket.c
> index b8c931e..52f9dce 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -33,6 +33,7 @@
>  #include "qemu/sockets.h"
>  #include "qemu/iov.h"
>  #include "qemu/main-loop.h"
> +#include "io/channel-socket.h"
>  
>  typedef struct NetSocketState {
>      NetClientState nc;
> @@ -525,16 +526,22 @@ typedef struct {
>      char *name;
>  } socket_connect_data;
>  
> -static void socket_connect_data_free(socket_connect_data *c)
> +static void socket_connect_data_free(void *opaque)
>  {
> +    socket_connect_data *c = opaque;
> +    if (!c) {
> +        return;
> +    }
> +
>      qapi_free_SocketAddress(c->saddr);
>      g_free(c->model);
>      g_free(c->name);
>      g_free(c);
>  }
>  
> -static void net_socket_connected(int fd, Error *err, void *opaque)
> +static void net_socket_connected(QIOTask *task, void *opaque)
>  {
> +    QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(qio_task_get_source(task));
>      socket_connect_data *c = opaque;
>      NetSocketState *s;
>      char *addr_str = NULL;
> @@ -543,13 +550,13 @@ static void net_socket_connected(int fd, Error *err, void *opaque)
>      addr_str = socket_address_to_string(c->saddr, &local_error);
>      if (addr_str == NULL) {
>          error_report_err(local_error);
> -        closesocket(fd);
> +        closesocket(sioc->fd);
>          goto end;
>      }
>  
> -    s = net_socket_fd_init(c->peer, c->model, c->name, fd, true);
> +    s = net_socket_fd_init(c->peer, c->model, c->name, sioc->fd, true);
>      if (!s) {
> -        closesocket(fd);
> +        closesocket(sioc->fd);
>          goto end;
>      }
>  
> @@ -567,7 +574,7 @@ static int net_socket_connect_init(NetClientState *peer,
>                                     const char *host_str)
>  {
>      socket_connect_data *c = g_new0(socket_connect_data, 1);
> -    int fd = -1;
> +    QIOChannelSocket *sioc;
>      Error *local_error = NULL;
>  
>      c->peer = peer;
> @@ -578,11 +585,12 @@ static int net_socket_connect_init(NetClientState *peer,
>          goto err;
>      }
>  
> -    fd = socket_connect(c->saddr, net_socket_connected, c, &local_error);
> -    if (fd < 0) {
> -        goto err;
> -    }
> -
> +    sioc = qio_channel_socket_new();
> +    qio_channel_socket_connect_async(sioc,
> +                                     c->saddr,
> +                                     net_socket_connected,
> +                                     c,
> +                                     NULL);
>      return 0;

You've not saved a copy of the QIOChannelSocket poiinter here, and
the net_socket_connected() method doesn't release the reference
either. So htere is a memory leak. Of course if you relesae the
reference in net_socket_connected(), then you need to dup() the
file descriptor you're borrowing.

Regards,
Daniel
-- 
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Hi, Daniel

On 04/28/2017 12:20 AM, Daniel P. Berrange wrote:
> On Wed, Apr 26, 2017 at 04:04:15PM +0800, Mao Zhongyi wrote:
>> Currently, socket connection in net is realized by an old
>> mechanism which is non-blocking.

[...]

             NULL);
>>      return 0;
>
> You've not saved a copy of the QIOChannelSocket poiinter here, and
> the net_socket_connected() method doesn't release the reference
> either. So htere is a memory leak. Of course if you relesae the
> reference in net_socket_connected(), then you need to dup() the
> file descriptor you're borrowing.
>
> Regards,
> Daniel


Sorry for delay, thanks for your detailed reply.
I see, will fix it in the next version.

Thanks
Mao
>