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dbus: stash the subscriber list when we disconenct from the bus

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If we unexpectly disconnect from the bus, systemd would end up dropping
the list of subscribers, which breaks the ability of clients like logind
to monitor the state of units.

Stash the list of subscribers into the deserialized state in the event
of a disconnect so that when we recover we can renew the broken
subscriptions.
This commit is contained in:
Ronan Pigott 2024-11-28 12:53:32 -07:00
parent c5f95bc19b
commit 1b58645207
5 changed files with 47 additions and 11 deletions
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25
src/core/dbus.c
View File

@ -860,6 +860,10 @@ int bus_init_api(Manager *m) {
if (r < 0)
return log_error_errno(r, "Failed to set up API bus: %m");
r = bus_track_coldplug(bus, &m->subscribed, /* recursive= */ false, m->deserialized_subscribed);
if (r < 0)
return r;
m->deserialized_subscribed = strv_free(m->deserialized_subscribed);
m->api_bus = TAKE_PTR(bus);
return 0;
@ -1004,8 +1008,19 @@ static void destroy_bus(Manager *m, sd_bus **bus) {
}
/* Get rid of tracked clients on this bus */
if (m->subscribed && sd_bus_track_get_bus(m->subscribed) == *bus)
if (m->subscribed && sd_bus_track_get_bus(m->subscribed) == *bus) {
_cleanup_strv_free_ char **subscribed = NULL;
int r;
r = bus_track_to_strv(m->subscribed, &subscribed);
if (r < 0)
log_error_errno(r, "Failed to serialize api subscribers: %m");
r = strv_extend_strv_consume(&m->deserialized_subscribed, TAKE_PTR(subscribed), /* filter_duplicates = */ false);
if (r < 0)
log_error_errno(r, "Failed to record api subscribers: %m");
m->subscribed = sd_bus_track_unref(m->subscribed);
}
HASHMAP_FOREACH(j, m->jobs)
if (j->bus_track && sd_bus_track_get_bus(j->bus_track) == *bus)
@ -1064,7 +1079,6 @@ void bus_done(Manager *m) {
assert(!m->subscribed);
m->deserialized_subscribed = strv_free(m->deserialized_subscribed);
m->polkit_registry = hashmap_free(m->polkit_registry);
}
@ -1153,20 +1167,19 @@ void bus_track_serialize(sd_bus_track *t, FILE *f, const char *prefix) {
}
}
int bus_track_coldplug(Manager *m, sd_bus_track **t, bool recursive, char **l) {
int bus_track_coldplug(sd_bus *bus, sd_bus_track **t, bool recursive, char **l) {
int r;
assert(m);
assert(t);
if (strv_isempty(l))
return 0;
if (!m->api_bus)
if (!bus)
return 0;
if (!*t) {
r = sd_bus_track_new(m->api_bus, t, NULL, NULL);
r = sd_bus_track_new(bus, t, NULL, NULL);
if (r < 0)
return r;
}

2
src/core/dbus.h
View File

@ -19,7 +19,7 @@ void bus_done(Manager *m);
int bus_fdset_add_all(Manager *m, FDSet *fds);
void bus_track_serialize(sd_bus_track *t, FILE *f, const char *prefix);
int bus_track_coldplug(Manager *m, sd_bus_track **t, bool recursive, char **l);
int bus_track_coldplug(sd_bus *bus, sd_bus_track **t, bool recursive, char **l);
int bus_foreach_bus(Manager *m, sd_bus_track *subscribed2, int (*send_message)(sd_bus *bus, void *userdata), void *userdata);

8
src/core/manager.c
View File

@ -1803,6 +1803,9 @@ Manager* manager_free(Manager *m) {
free(m->switch_root);
free(m->switch_root_init);
sd_bus_track_unref(m->subscribed);
strv_free(m->deserialized_subscribed);
unit_defaults_done(&m->defaults);
FOREACH_ARRAY(map, m->units_needing_mounts_for, _UNIT_MOUNT_DEPENDENCY_TYPE_MAX) {
@ -2139,7 +2142,7 @@ int manager_startup(Manager *m, FILE *serialization, FDSet *fds, const char *roo
manager_setup_bus(m);
/* Now that we are connected to all possible buses, let's deserialize who is tracking us. */
r = bus_track_coldplug(m, &m->subscribed, false, m->deserialized_subscribed);
r = bus_track_coldplug(m->api_bus, &m->subscribed, false, m->deserialized_subscribed);
if (r < 0)
log_warning_errno(r, "Failed to deserialized tracked clients, ignoring: %m");
m->deserialized_subscribed = strv_free(m->deserialized_subscribed);
@ -3813,9 +3816,6 @@ int manager_reload(Manager *m) {
/* Clean up runtime objects no longer referenced */
manager_vacuum(m);
/* Clean up deserialized tracked clients */
m->deserialized_subscribed = strv_free(m->deserialized_subscribed);
/* Consider the reload process complete now. */
assert(m->n_reloading > 0);
m->n_reloading--;

22
src/shared/bus-util.c
View File

@ -698,6 +698,28 @@ int bus_track_add_name_many(sd_bus_track *t, char **l) {
return r;
}
int bus_track_to_strv(sd_bus_track *t, char ***ret) {
_cleanup_strv_free_ char **subscribed = NULL;
int r = 0;
assert(ret);
for (const char *n = sd_bus_track_first(t); n; n = sd_bus_track_next(t)) {
r = sd_bus_track_count_name(t, n);
if (r < 0)
return r;
for (int j = 0; j < r; j++) {
r = strv_extend(&subscribed, n);
if (r < 0)
return r;
}
}
*ret = TAKE_PTR(subscribed);
return r;
}
int bus_open_system_watch_bind_with_description(sd_bus **ret, const char *description) {
_cleanup_(sd_bus_close_unrefp) sd_bus *bus = NULL;
const char *e;

1
src/shared/bus-util.h
View File

@ -66,6 +66,7 @@ int bus_path_encode_unique(sd_bus *b, const char *prefix, const char *sender_id,
int bus_path_decode_unique(const char *path, const char *prefix, char **ret_sender, char **ret_external);
int bus_track_add_name_many(sd_bus_track *t, char **l);
int bus_track_to_strv(sd_bus_track *t, char ***ret);
int bus_open_system_watch_bind_with_description(sd_bus **ret, const char *description);
static inline int bus_open_system_watch_bind(sd_bus **ret) {