diff mbox

[PULL,11/41] char: forbid direct chardevice access for hotswap devices

Message ID 1499955874-10954-12-git-send-email-pbonzini@redhat.com
State New
Headers show

Commit Message

Paolo Bonzini July 13, 2017, 2:24 p.m. UTC 
From: Anton Nefedov <anton.nefedov@virtuozzo.com>

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.nefedov@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1499342940-56739-5-git-send-email-anton.nefedov@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 chardev/char-fe.c         |  7 +++++++
 include/chardev/char-fe.h | 10 ++++++++++
 2 files changed, 17 insertions(+)
diff mbox

Patch

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;
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