Commit 02c4bdf1 tried to make signal=on the default for stdio chardevs
except for '-serial mon:stdio', but it forgot about QMP and accidentally
switched the QMP default from true (except for -nographic) to false
(always). The QMP documentation was kept unchanged and still describes
the opposite of the old behaviour (which is an even older documentation
bug).

Fix all of this by making signal=true the default in ChardevStdio and
documenting it as such.

Fixes: 02c4bdf1d2ca8c02a9bae16398f260b5c08d08bf
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 qapi/char.json       | 3 +--
 chardev/char-stdio.c | 4 +---
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/qapi/char.json b/qapi/char.json
index b4d66ec90b..43486d1daa 100644
--- a/qapi/char.json
+++ b/qapi/char.json
@@ -321,8 +321,7 @@
 # Configuration info for stdio chardevs.
 #
 # @signal: Allow signals (such as SIGINT triggered by ^C)
-#          be delivered to qemu.  Default: true in -nographic mode,
-#          false otherwise.
+#          be delivered to qemu.  Default: true.
 #
 # Since: 1.5
 ##
diff --git a/chardev/char-stdio.c b/chardev/char-stdio.c
index 82eaebc1db..403da308c9 100644
--- a/chardev/char-stdio.c
+++ b/chardev/char-stdio.c
@@ -112,9 +112,7 @@ static void qemu_chr_open_stdio(Chardev *chr,
 
     qemu_chr_open_fd(chr, 0, 1);
 
-    if (opts->has_signal) {
-        stdio_allow_signal = opts->signal;
-    }
+    stdio_allow_signal = !opts->has_signal || opts->signal;
     qemu_chr_set_echo_stdio(chr, false);
 }
 #endif
-- 
2.28.0