[Qemu-devel] [PATCH] qemu-char: another io_add_watch_poll fix

[Paolo Bonzini <pbonzini@redhat.com>]

After attaching the source, we have to remove the reference we hold
to it, because we do not hold anymore a pointer to the source.

If we do not do this, removing the source will not finalize it and
will not drop the "real" I/O watch source.

This showed up when backporting the new flow control patches to older
versions of QEMU that still used select.  The whole select then failed
with EBADF (poll instead will reporting POLLNVAL on a single pollfd)
and QEMU froze.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 qemu-char.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/qemu-char.c b/qemu-char.c
index 37117b5..2caef56 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -610,6 +610,7 @@ static guint io_add_watch_poll(GIOChannel *channel,
                                gpointer user_data)
 {
     IOWatchPoll *iwp;
+    int tag;
 
     iwp = (IOWatchPoll *) g_source_new(&io_watch_poll_funcs, sizeof(IOWatchPoll));
     iwp->fd_can_read = fd_can_read;
@@ -618,7 +619,9 @@ static guint io_add_watch_poll(GIOChannel *channel,
     iwp->fd_read = (GSourceFunc) fd_read;
     iwp->src = NULL;
 
-    return g_source_attach(&iwp->parent, NULL);
+    tag = g_source_attach(&iwp->parent, NULL);
+    g_source_unref(&iwp->parent);
+    return tag;
 }
 
 static GIOChannel *io_channel_from_fd(int fd)
-- 
1.8.1.4