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net/filter-redirector: add support for dynamic status on/off switching

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Currently, filter-redirector does not implement the status_changed
callback, which means the 'status' property cannot be used to
dynamically enable/disable the filter at runtime. When status is
set to 'off' via QMP/HMP, the filter still receives data from the
indev chardev because the chardev handlers remain registered.

This patch adds proper support for the 'status' property:

1. Implement filter_redirector_status_changed() callback:
   - When status changes to 'off': remove chardev read handlers
   - When status changes to 'on': re-register chardev handlers
     (only if chardev is already open)

2. Update filter_redirector_setup() to respect initial status:
   - If filter is created with status=off, do not register handlers
   - This allows creating disabled filters via command line or QMP

3. Handle chardev OPENED/CLOSED events to re-arm handlers on reconnect:
   - Keep the chr_event callback installed on CLOSE so a later OPENED
     can re-register the read handlers when nf->on
   - Use qemu_chr_fe_set_handlers_full(..., set_open=false, sync_state=false)
     instead of qemu_chr_fe_set_handlers() because the latter forces
     sync_state=true and may emit CHR_EVENT_OPENED for an already-open
     backend. Doing that from inside the chr_event callback would cause
     recursive/re-entrant OPENED handling.

Signed-off-by: Jason Wang <jasowang@redhat.com>
This commit is contained in:
Jason Wang
2026-01-04 15:54:10 +08:00
parent 50f6d44850
commit 5193528b9f
1 changed files with 33 additions and 5 deletions
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38
net/filter-mirror.c
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@@ -179,9 +179,16 @@ static void redirector_chr_event(void *opaque, QEMUChrEvent event)
MirrorState *s = FILTER_REDIRECTOR(nf);
switch (event) {
case CHR_EVENT_OPENED:
if (nf->on) {
qemu_chr_fe_set_handlers_full(&s->chr_in, redirector_chr_can_read,
redirector_chr_read, redirector_chr_event,
NULL, nf, NULL, false, false);
}
break;
case CHR_EVENT_CLOSED:
qemu_chr_fe_set_handlers(&s->chr_in, NULL, NULL, NULL,
NULL, NULL, NULL, true);
qemu_chr_fe_set_handlers_full(&s->chr_in, NULL, NULL, redirector_chr_event,
NULL, nf, NULL, false, false);
break;
default:
break;
@@ -306,9 +313,11 @@ static void filter_redirector_setup(NetFilterState *nf, Error **errp)
return;
}
qemu_chr_fe_set_handlers(&s->chr_in, redirector_chr_can_read,
redirector_chr_read, redirector_chr_event,
NULL, nf, NULL, true);
if (nf->on) {
qemu_chr_fe_set_handlers(&s->chr_in, redirector_chr_can_read,
redirector_chr_read, redirector_chr_event,
NULL, nf, NULL, true);
}
}
if (s->outdev) {
@@ -324,6 +333,24 @@ static void filter_redirector_setup(NetFilterState *nf, Error **errp)
}
}
static void filter_redirector_status_changed(NetFilterState *nf, Error **errp)
{
MirrorState *s = FILTER_REDIRECTOR(nf);
if (!s->indev) {
return;
}
if (nf->on) {
qemu_chr_fe_set_handlers(&s->chr_in, redirector_chr_can_read,
redirector_chr_read, redirector_chr_event,
NULL, nf, NULL, true);
} else {
qemu_chr_fe_set_handlers(&s->chr_in, NULL, NULL, NULL,
NULL, NULL, NULL, true);
}
}
static char *filter_redirector_get_indev(Object *obj, Error **errp)
{
MirrorState *s = FILTER_REDIRECTOR(obj);
@@ -440,6 +467,7 @@ static void filter_redirector_class_init(ObjectClass *oc, const void *data)
nfc->setup = filter_redirector_setup;
nfc->cleanup = filter_redirector_cleanup;
nfc->receive_iov = filter_redirector_receive_iov;
nfc->status_changed = filter_redirector_status_changed;
}
static void filter_mirror_init(Object *obj)