qemu_chr_fe_get_driver() is unsafe, frontends with hotswap support
should not access CharDriver ptr directly as CharDriver might change.
Signed-off-by: Anton Nefedov <anton.nefe...@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
Reviewed-by: Marc-André Lureau <marcandre.lur...@redhat.com>
---
include/chardev/char-fe.h | 10 ++++++++++
chardev/char-fe.c | 7 +++++++
2 files changed, 17 insertions(+)
diff --git a/include/chardev/char-fe.h b/include/chardev/char-fe.h
index 9f38060..588abed 100644
--- a/include/chardev/char-fe.h
+++ b/include/chardev/char-fe.h
@@ -46,10 +46,20 @@ void qemu_chr_fe_deinit(CharBackend *b, bool del);
*
* Returns the driver associated with a CharBackend or NULL if no
* associated Chardev.
+ * Note: avoid this function as the driver should never be accessed directly,
+ * especially by the frontends that support chardevice hotswap.
+ * Consider qemu_chr_fe_backend_connected() to check for driver existence
*/
Chardev *qemu_chr_fe_get_driver(CharBackend *be);
/**
+ * @qemu_chr_fe_backend_connected:
+ *
+ * Returns true if there is a chardevice associated with @be.
+ */
+bool qemu_chr_fe_backend_connected(CharBackend *be);
+
+/**
* @qemu_chr_fe_set_handlers:
* @b: a CharBackend
* @fd_can_read: callback to get the amount of data the frontend may
diff --git a/chardev/char-fe.c b/chardev/char-fe.c
index 7054863..de5ba3c 100644
--- a/chardev/char-fe.c
+++ b/chardev/char-fe.c
@@ -179,9 +179,16 @@ void qemu_chr_fe_printf(CharBackend *be, const char *fmt,
...)
Chardev *qemu_chr_fe_get_driver(CharBackend *be)
{
+ /* this is unsafe for the users that support chardev hotswap */
+ assert(be->chr_be_change == NULL);
return be->chr;
}
+bool qemu_chr_fe_backend_connected(CharBackend *be)
+{
+ return !!be->chr;
+}
+
bool qemu_chr_fe_init(CharBackend *b, Chardev *s, Error **errp)
{
int tag = 0;
--
2.7.4
