[Qemu-devel] [PATCH 0/2] char, virtio_console: Allow chardevs to be re-used

[Qemu-devel] [PATCH 0/2] char, virtio_console: Allow chardevs to be re-used

[Amit Shah]

This series does two things:
- prevents a single chardev to be used by multiple devices at the same
  time
- virtio-console/serial ports don't close a chardev, instead free it
  for later use by other devices (or a new hot-plugged virtio serial
  port).

Please apply.

Amit Shah (2):
  virtio-console: Keep chardev open for other users after hot-unplug
  char: Prevent multiple devices opening same chardev

 hw/qdev-properties.c |    7 ++++++-
 hw/virtio-console.c  |    6 +++++-
 qemu-char.c          |    4 ++++
 qemu-char.h          |    1 +
 4 files changed, 16 insertions(+), 2 deletions(-)

-- 
1.7.4

[Qemu-devel] [PATCH 1/2] virtio-console: Keep chardev open for other users after hot-unplug

[Amit Shah]

After a hot-unplug operation, the previous behaviour was to close the
chardev.  That meant the chardev couldn't be re-used.  Also, since
chardev hot-plug isn't possible so far, this means virtio-console
hot-plug isn't feasible as well.

With this change, the chardev is kept around.  A new virtio-console
channel can then be hot-plugged with the same chardev and things will
continue to work.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/virtio-console.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index c235b27..84ed572 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -82,7 +82,11 @@ static int virtconsole_exitfn(VirtIOSerialPort *port)
 
     if (vcon->chr) {
         port->info->have_data = NULL;
-        qemu_chr_close(vcon->chr);
+	/*
+	 * Instead of closing the chardev, free it so it can be used
+	 * for other purposes.
+	 */
+	qemu_chr_add_handlers(vcon->chr, NULL, NULL, NULL, NULL);
     }
 
     return 0;
-- 
1.7.4

[Qemu-devel] [PATCH 2/2] char: Prevent multiple devices opening same chardev

[Amit Shah]

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 deletions(-)

diff --git a/hw/qdev-properties.c b/hw/qdev-properties.c
index a45b61e..1088a26 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 bd4e944..524cdc1 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 56d9954..fb96eef 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;
 };
 
-- 
1.7.4