vnc: don't mess up with iohandlers in the vnc thread

The threaded VNC servers messed up with QEMU fd handlers without
any kind of locking, and that can cause some nasty race conditions.

Using qemu_mutex_lock_iothread() won't work because vnc_dpy_cpy(),
which will wait for the current job queue to finish, can be called with
the iothread lock held.

Instead, we now store the data in a temporary buffer, and use a bottom
half to notify the main thread that new data is available.

vnc_[un]lock_ouput() is still needed to access VncState members like
abort, csock or jobs_buffer.

Signed-off-by: Corentin Chary <corentin.chary@gmail.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/ui/vnc.h b/ui/vnc.h
index 0bd1fc6..a851ebd 100644
--- a/ui/vnc.h
+++ b/ui/vnc.h
@@ -304,6 +304,8 @@ struct VncState
     VncJob job;
 #else
     QemuMutex output_mutex;
+    QEMUBH *bh;
+    Buffer jobs_buffer;
 #endif
 
     /* Encoding specific, if you add something here, don't forget to