[PATCH] char: Slightly better error reporting when chardev is in use

[Markus Armbruster]

Both

    $ qemu-system-x86_64 -chardev null,id=chr0,mux=on -mon chardev=chr0 -mon 
chardev=chr0 -mon chardev=chr0 -mon chardev=chr0 -mon chardev=chr0

and

    $ qemu-system-x86_64 -chardev null,id=chr0 -mon chardev=chr0 -mon 
chardev=chr0
fail with

    qemu-system-x86_64: -mon chardev=chr0: Device 'chr0' is in use

Improve to

    qemu-system-x86_64: -mon chardev=chr0: too many uses of multiplexed chardev 
'chr0' (maximum is 4)

and

    qemu-system-x86_64: -mon chardev=chr0: chardev 'chr0' is already in use

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 chardev/char-fe.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/chardev/char-fe.c b/chardev/char-fe.c
index 20222a4cad..66cee8475a 100644
--- a/chardev/char-fe.c
+++ b/chardev/char-fe.c
@@ -199,13 +199,18 @@ bool qemu_chr_fe_init(CharBackend *b, Chardev *s, Error 
**errp)
             MuxChardev *d = MUX_CHARDEV(s);
 
             if (d->mux_cnt >= MAX_MUX) {
-                goto unavailable;
+                error_setg(errp,
+                           "too many uses of multiplexed chardev '%s'"
+                           " (maximum is " stringify(MAX_MUX) ")",
+                           s->label);
+                return false;
             }
 
             d->backends[d->mux_cnt] = b;
             tag = d->mux_cnt++;
         } else if (s->be) {
-            goto unavailable;
+            error_setg(errp, "chardev '%s' is already in use", s->label);
+            return false;
         } else {
             s->be = b;
         }
@@ -215,10 +220,6 @@ bool qemu_chr_fe_init(CharBackend *b, Chardev *s, Error 
**errp)
     b->tag = tag;
     b->chr = s;
     return true;
-
-unavailable:
-    error_setg(errp, QERR_DEVICE_IN_USE, s->label);
-    return false;
 }
 
 void qemu_chr_fe_deinit(CharBackend *b, bool del)
-- 
2.44.0