[PATCH v20 04/15] net/tap: move vhost-net open() calls to tap_parse_vhost_fds()

1. Simplify code path: get vhostfds for all cases in one function.

2. Prepare for further tap-fd-migraton feature, when we'll need to
postpone vhost initialization up to post-load stage.

Signed-off-by: Vladimir Sementsov-Ogievskiy <[email protected]>
Reviewed-by: Ben Chaney <[email protected]>
---
 net/tap.c | 39 ++++++++++++++++++++++-----------------
 1 file changed, 22 insertions(+), 17 deletions(-)

diff --git a/net/tap.c b/net/tap.c
index f4051e8d4b1..bec2cd48fd3 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -756,8 +756,7 @@ static bool net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
         }
     }
 
-    if (tap->has_vhost ? tap->vhost :
-        (vhostfd != -1) || (tap->has_vhostforce && tap->vhostforce)) {
+    if (vhostfd != -1) {
         VhostNetOptions options;
 
         options.backend_type = VHOST_BACKEND_TYPE_KERNEL;
@@ -767,17 +766,6 @@ static bool net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
         } else {
             options.busyloop_timeout = 0;
         }
-
-        if (vhostfd == -1) {
-            vhostfd = open("/dev/vhost-net", O_RDWR);
-            if (vhostfd < 0) {
-                error_setg_file_open(errp, errno, "/dev/vhost-net");
-                goto failed;
-            }
-            if (!qemu_set_blocking(vhostfd, false, errp)) {
-                goto failed;
-            }
-        }
         options.opaque = (void *)(uintptr_t)vhostfd;
         options.nvqs = 2;
         options.feature_bits = kernel_feature_bits;
@@ -863,14 +851,31 @@ static int tap_parse_fds_and_queues(const NetdevTapOptions *tap, int **fds,
 static bool tap_parse_vhost_fds(const NetdevTapOptions *tap, int **vhost_fds,
                                 int queues, Error **errp)
 {
-    if (!(tap->vhostfd || tap->vhostfds)) {
+    bool need_vhost = tap->has_vhost ? tap->vhost :
+        ((tap->vhostfd || tap->vhostfds) ||
+         (tap->has_vhostforce && tap->vhostforce));
+
+    if (!need_vhost) {
         *vhost_fds = NULL;
         return true;
     }
 
-    if (net_parse_fds(tap->vhostfd ?: tap->vhostfds,
-                      vhost_fds, queues, errp) < 0) {
-        return false;
+    if (tap->vhostfd || tap->vhostfds) {
+        if (net_parse_fds(tap->vhostfd ?: tap->vhostfds,
+                          vhost_fds, queues, errp) < 0) {
+            return false;
+        }
+    } else {
+        *vhost_fds = g_new(int, queues);
+        for (int i = 0; i < queues; i++) {
+            int vhostfd = open("/dev/vhost-net", O_RDWR);
+            if (vhostfd < 0) {
+                error_setg_file_open(errp, errno, "/dev/vhost-net");
+                net_free_fds(*vhost_fds, i);
+                return false;
+            }
+            (*vhost_fds)[i] = vhostfd;
+        }
     }
 
     if (!unblock_fds(*vhost_fds, queues, errp)) {
-- 
2.43.0