qemu-char: Call fe_claim / fe_release when not using qdev chr properties

chardev-frontends need to explictly check, increase and decrement the
avail_connections "property" of the chardev when they are not using a
qdev-chardev-property for the chardev.

This fixes things like:
qemu-kvm -chardev stdio,id=foo -device isa-serial,chardev=foo \
  -mon chardev=foo

Working, where they should fail. Most of the changes here are due to
old hardware emulation code which is using serial_hds directly rather then
a qdev-chardev-property.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Message-id: 1364412581-3672-3-git-send-email-hdegoede@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 14 insertions, 4 deletions

diff --git a/hw/xen_console.c b/hw/xen_console.c
index a8db6f8d8f..c56ef4737f 100644
--- a/hw/xen_console.c
+++ b/hw/xen_console.c
@@ -241,9 +241,17 @@ static int con_initialise(struct XenDevice *xendev)
 	return -1;
 
     xen_be_bind_evtchn(&con->xendev);
-    if (con->chr)
-        qemu_chr_add_handlers(con->chr, xencons_can_receive, xencons_receive,
-                              NULL, con);
+    if (con->chr) {
+        if (qemu_chr_fe_claim(con->chr) == 0) {
+            qemu_chr_add_handlers(con->chr, xencons_can_receive,
+                                  xencons_receive, NULL, con);
+        } else {
+            xen_be_printf(xendev, 0,
+                          "xen_console_init error chardev %s already used\n",
+                          con->chr->label);
+            con->chr = NULL;
+        }
+    }
 
     xen_be_printf(xendev, 1, "ring mfn %d, remote port %d, local port %d, limit %zd\n",
 		  con->ring_ref,
@@ -260,8 +268,10 @@ static void con_disconnect(struct XenDevice *xendev)
     if (!xendev->dev) {
         return;
     }
-    if (con->chr)
+    if (con->chr) {
         qemu_chr_add_handlers(con->chr, NULL, NULL, NULL, NULL);
+        qemu_chr_fe_release(con->chr);
+    }
     xen_be_unbind_evtchn(&con->xendev);
 
     if (con->sring) {