From 2d6c1ef40f3678ab47a4d14fb5dadaa486bfcda6 Mon Sep 17 00:00:00 2001
From: Amit Shah <amit.shah@redhat.com>
Date: Thu, 10 Feb 2011 12:55:20 +0530
Subject: [PATCH] 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>
---
 hw/qdev-properties.c | 7 ++++++-
 qemu-char.c          | 4 ++++
 qemu-char.h          | 1 +
 3 files changed, 11 insertions(+), 1 deletion(-)

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;
 }
 
diff --git a/qemu-char.c b/qemu-char.c
index cad35d7717..c4557c30d0 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -197,6 +197,10 @@ void qemu_chr_add_handlers(CharDriverState *s,
                            IOEventHandler *fd_event,
                            void *opaque)
 {
+    if (!opaque) {
+        /* chr driver being released. */
+        s->assigned = 0;
+    }
     s->chr_can_read = fd_can_read;
     s->chr_read = fd_read;
     s->chr_event = fd_event;
diff --git a/qemu-char.h b/qemu-char.h
index 56d9954c52..fb96eef3de 100644
--- a/qemu-char.h
+++ b/qemu-char.h
@@ -70,6 +70,7 @@ struct CharDriverState {
     char *label;
     char *filename;
     int opened;
+    int assigned; /* chardev assigned to a device */
     QTAILQ_ENTRY(CharDriverState) next;
 };