[libvirt] [PATCH] qemu: Mark graphics ports used on reconnect

[Michal Privoznik]

This is an issue that's bugging me for a long time. I don't know
exactly when and who is to blame but on daemon reconnect we lose
qemu's port allocator internal state. That's okay as we should be
able to rebuild it later. However, now I'm seeing port allocator
biding successfully to ports that are already taken by qemu
(either VNC or Spice). Thus any attempt to start another domain
after daemon is restarted fails because libvirt instructs qemu to
take port 5900 which is already taken.

Now, I don't want to mask the real problem, but one can advocate
that we should be marking graphics ports as already in use on
qemuProcessReconnect anyway, because we already know that they
are taken.

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 src/qemu/qemu_process.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index d3155e4e7..053aba1a6 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -4035,7 +4035,8 @@ qemuProcessStartHook(virQEMUDriverPtr driver,
 
 static int
 qemuProcessGraphicsReservePorts(virQEMUDriverPtr driver,
-                                virDomainGraphicsDefPtr graphics)
+                                virDomainGraphicsDefPtr graphics,
+                                bool reconnect)
 {
     virDomainGraphicsListenDefPtr glisten;
 
@@ -4050,7 +4051,8 @@ qemuProcessGraphicsReservePorts(virQEMUDriverPtr driver,
 
     switch (graphics->type) {
     case VIR_DOMAIN_GRAPHICS_TYPE_VNC:
-        if (!graphics->data.vnc.autoport) {
+        if (!graphics->data.vnc.autoport ||
+            reconnect) {
             if (virPortAllocatorSetUsed(driver->remotePorts,
                                         graphics->data.vnc.port,
                                         true) < 0)
@@ -4065,7 +4067,7 @@ qemuProcessGraphicsReservePorts(virQEMUDriverPtr driver,
         break;
 
     case VIR_DOMAIN_GRAPHICS_TYPE_SPICE:
-        if (graphics->data.spice.autoport)
+        if (graphics->data.spice.autoport && !reconnect)
             return 0;
 
         if (graphics->data.spice.port > 0) {
@@ -4269,7 +4271,7 @@ qemuProcessSetupGraphics(virQEMUDriverPtr driver,
         for (i = 0; i < vm->def->ngraphics; i++) {
             graphics = vm->def->graphics[i];
 
-            if (qemuProcessGraphicsReservePorts(driver, graphics) < 0)
+            if (qemuProcessGraphicsReservePorts(driver, graphics, false) < 0)
                 goto cleanup;
         }
     }
@@ -6881,6 +6883,13 @@ qemuProcessReconnect(void *opaque)
             goto error;
     }
 
+    for (i = 0; i < obj->def->ngraphics; i++) {
+        if (qemuProcessGraphicsReservePorts(driver,
+                                            obj->def->graphics[i],
+                                            true) < 0)
+            goto error;
+    }
+
     if (qemuProcessUpdateState(driver, obj) < 0)
         goto error;
 
-- 
2.13.5