chardev/mux: implement detach of frontends from mux

With bitset management now it becomes feasible to implement
the logic of detaching frontends from multiplexer.

Signed-off-by: Roman Penyaev <r.peniaev@gmail.com>
Cc: "Marc-André Lureau" <marcandre.lureau@redhat.com>
Cc: qemu-devel@nongnu.org
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-ID: <20241014152408.427700-8-r.peniaev@gmail.com>

1 files changed, 18 insertions, 3 deletions

diff --git a/chardev/char-mux.c b/chardev/char-mux.c
index 4fc619b..bda5c45 100644
--- a/chardev/char-mux.c
+++ b/chardev/char-mux.c
@@ -290,10 +290,10 @@ static void char_mux_finalize(Object *obj)
     bit = -1;
     while ((bit = find_next_bit(&d->mux_bitset, MAX_MUX, bit + 1)) < MAX_MUX) {
         CharBackend *be = d->backends[bit];
-        if (be) {
-            be->chr = NULL;
-        }
+        be->chr = NULL;
+        d->backends[bit] = NULL;
     }
+    d->mux_bitset = 0;
     qemu_chr_fe_deinit(&d->chr, false);
 }
 
@@ -332,6 +332,21 @@ bool mux_chr_attach_frontend(MuxChardev *d, CharBackend *b,
     return true;
 }
 
+bool mux_chr_detach_frontend(MuxChardev *d, unsigned int tag)
+{
+    unsigned int bit;
+
+    bit = find_next_bit(&d->mux_bitset, MAX_MUX, tag);
+    if (bit != tag) {
+        return false;
+    }
+
+    d->mux_bitset &= ~(1 << bit);
+    d->backends[bit] = NULL;
+
+    return true;
+}
+
 void mux_set_focus(Chardev *chr, unsigned int focus)
 {
     MuxChardev *d = MUX_CHARDEV(chr);