[PATCH v2 7/8] chardev/mux: implement detach of frontends from mux

[Roman Penyaev <r.peniaev@gmail.com>]

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
---
 chardev/char-fe.c          |  2 +-
 chardev/char-mux.c         | 21 ++++++++++++++++++---
 chardev/chardev-internal.h |  1 +
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/chardev/char-fe.c b/chardev/char-fe.c
index 3b8771ca2ac4..8ac6bebb6f74 100644
--- a/chardev/char-fe.c
+++ b/chardev/char-fe.c
@@ -225,7 +225,7 @@ void qemu_chr_fe_deinit(CharBackend *b, bool del)
         }
         if (CHARDEV_IS_MUX(b->chr)) {
             MuxChardev *d = MUX_CHARDEV(b->chr);
-            d->backends[b->tag] = NULL;
+            mux_chr_detach_frontend(d, b->tag);
         }
         if (del) {
             Object *obj = OBJECT(b->chr);
diff --git a/chardev/char-mux.c b/chardev/char-mux.c
index 4fc619b2da70..bda5c45e6058 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);
diff --git a/chardev/chardev-internal.h b/chardev/chardev-internal.h
index b89aada5413b..853807f3cb88 100644
--- a/chardev/chardev-internal.h
+++ b/chardev/chardev-internal.h
@@ -61,6 +61,7 @@ DECLARE_INSTANCE_CHECKER(MuxChardev, MUX_CHARDEV,
 
 bool mux_chr_attach_frontend(MuxChardev *d, CharBackend *b,
                              unsigned int *tag, Error **errp);
+bool mux_chr_detach_frontend(MuxChardev *d, unsigned int tag);
 void mux_set_focus(Chardev *chr, unsigned int focus);
 void mux_chr_send_all_event(Chardev *chr, QEMUChrEvent event);
 
-- 
2.34.1