char: Prevent multiple devices opening same chardev

Prevent:

-chardev socket,path=/tmp/foo,server,nowait,id=c0 \
-device virtserialport,chardev=c0,id=vs0 \
-device virtserialport,chardev=c0,id=vs1

Reported-by: Mike Cao <bcao@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/hw/qdev-properties.c b/hw/qdev-properties.c
index a45b61e7ed..1088a26f8e 100644
--- a/hw/qdev-properties.c
+++ b/hw/qdev-properties.c
@@ -351,8 +351,13 @@ static int parse_chr(DeviceState *dev, Property *prop, const char *str)
     CharDriverState **ptr = qdev_get_prop_ptr(dev, prop);
 
     *ptr = qemu_chr_find(str);
-    if (*ptr == NULL)
+    if (*ptr == NULL) {
         return -ENOENT;
+    }
+    if ((*ptr)->assigned) {
+        return -EEXIST;
+    }
+    (*ptr)->assigned = 1;
     return 0;
 }