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mirror of https://github.com/systemd/systemd-stable.git synced 2024-12-24 21:34:08 +03:00

core: convert Slice= into a proper dependency (and add a back dependency)

The slice a unit is assigned to is currently a UnitRef reference. Let's
turn it into a proper dependency, to simplify and clean up code a bit.
Now that new dep types are cheaper, deps should generally be preferable
over everything else, if the concept applies.

This brings one major benefit: we often have to iterate through all unit
a slice contains. So far we iterated through all Before= dependencies of
the slice unit to achieve that, filtering out unrelated units, and
taking benefit of the fact that slice units are implicitly ordered
Before= the units they contain. By making Slice= a proper dependency,
and having an accompanying SliceOf= dependency type, this is much
simpler and nicer as we can directly enumerate the units a slice
contains.

The forward dependency is actually called InSlice internally, since we
already used the UNIT_SLICE name as UnitType field. However, since we
don't intend to expose the dependency to users as dep anyway (we already
have the regular Slice D-Bus property for this) this shouldn't matter.
The SliceOf= implicit dependency type (the erverse of Slice=/InSlice=)
is exported over the bus, to make things a bit nicer to debug and
discoverable.
This commit is contained in:
Lennart Poettering 2021-04-13 18:37:25 +02:00
parent 12f64221b0
commit d219a2b07c
11 changed files with 66 additions and 54 deletions

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@ -1640,6 +1640,8 @@ node /org/freedesktop/systemd1/unit/avahi_2ddaemon_2eservice {
@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
readonly as JoinsNamespaceOf = ['...', ...];
@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
readonly as SliceOf = ['...', ...];
@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
readonly as RequiresMountsFor = ['...', ...];
@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
readonly as Documentation = ['...', ...];
@ -1775,6 +1777,8 @@ node /org/freedesktop/systemd1/unit/avahi_2ddaemon_2eservice {
<!--property JoinsNamespaceOf is not documented!-->
<!--property SliceOf is not documented!-->
<!--property FreezerState is not documented!-->
<!--property DropInPaths is not documented!-->
@ -1911,6 +1915,8 @@ node /org/freedesktop/systemd1/unit/avahi_2ddaemon_2eservice {
<variablelist class="dbus-property" generated="True" extra-ref="JoinsNamespaceOf"/>
<variablelist class="dbus-property" generated="True" extra-ref="SliceOf"/>
<variablelist class="dbus-property" generated="True" extra-ref="RequiresMountsFor"/>
<variablelist class="dbus-property" generated="True" extra-ref="Documentation"/>

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@ -282,6 +282,8 @@ static const char* const unit_dependency_table[_UNIT_DEPENDENCY_MAX] = {
[UNIT_JOINS_NAMESPACE_OF] = "JoinsNamespaceOf",
[UNIT_REFERENCES] = "References",
[UNIT_REFERENCED_BY] = "ReferencedBy",
[UNIT_IN_SLICE] = "InSlice",
[UNIT_SLICE_OF] = "SliceOf",
};
DEFINE_STRING_TABLE_LOOKUP(unit_dependency, UnitDependency);

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@ -245,6 +245,10 @@ typedef enum UnitDependency {
UNIT_REFERENCES, /* Inverse of 'references' is 'referenced_by' */
UNIT_REFERENCED_BY,
/* Slice= */
UNIT_IN_SLICE,
UNIT_SLICE_OF,
_UNIT_DEPENDENCY_MAX,
_UNIT_DEPENDENCY_INVALID = -EINVAL,
} UnitDependency;

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@ -1702,12 +1702,8 @@ CGroupMask unit_get_members_mask(Unit *u) {
if (u->type == UNIT_SLICE) {
Unit *member;
UNIT_FOREACH_DEPENDENCY(member, u, UNIT_ATOM_BEFORE) {
if (UNIT_DEREF(member->slice) != u)
continue;
UNIT_FOREACH_DEPENDENCY(member, u, UNIT_ATOM_SLICE_OF)
u->cgroup_members_mask |= unit_get_subtree_mask(member); /* note that this calls ourselves again, for the children */
}
}
u->cgroup_members_mask_valid = true;
@ -2362,13 +2358,10 @@ static int unit_realize_cgroup_now_disable(Unit *u, ManagerState state) {
if (u->type != UNIT_SLICE)
return 0;
UNIT_FOREACH_DEPENDENCY(m, u, UNIT_ATOM_BEFORE) {
UNIT_FOREACH_DEPENDENCY(m, u, UNIT_ATOM_SLICE_OF) {
CGroupMask target_mask, enable_mask, new_target_mask, new_enable_mask;
int r;
if (UNIT_DEREF(m->slice) != u)
continue;
/* The cgroup for this unit might not actually be fully realised yet, in which case it isn't
* holding any controllers open anyway. */
if (!m->cgroup_realized)
@ -2530,11 +2523,7 @@ void unit_add_family_to_cgroup_realize_queue(Unit *u) {
/* Children of u likely changed when we're called */
u->cgroup_members_mask_valid = false;
UNIT_FOREACH_DEPENDENCY(m, u, UNIT_ATOM_BEFORE) {
/* Skip units that have a dependency on the slice but aren't actually in it. */
if (UNIT_DEREF(m->slice) != u)
continue;
UNIT_FOREACH_DEPENDENCY(m, u, UNIT_ATOM_SLICE_OF) {
/* No point in doing cgroup application for units without active processes. */
if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(m)))
@ -3799,12 +3788,8 @@ void unit_invalidate_cgroup_bpf(Unit *u) {
if (u->type == UNIT_SLICE) {
Unit *member;
UNIT_FOREACH_DEPENDENCY(member, u, UNIT_ATOM_BEFORE) {
if (UNIT_DEREF(member->slice) != u)
continue;
UNIT_FOREACH_DEPENDENCY(member, u, UNIT_ATOM_SLICE_OF)
unit_invalidate_cgroup_bpf(member);
}
}
}

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@ -870,6 +870,7 @@ const sd_bus_vtable bus_unit_vtable[] = {
SD_BUS_PROPERTY("PropagatesReloadTo", "as", property_get_dependencies, 0, SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("ReloadPropagatedFrom", "as", property_get_dependencies, 0, SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("JoinsNamespaceOf", "as", property_get_dependencies, 0, SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("SliceOf", "as", property_get_dependencies, 0, SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("RequiresMountsFor", "as", property_get_requires_mounts_for, offsetof(Unit, requires_mounts_for), SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("Documentation", "as", NULL, offsetof(Unit, documentation), SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("Description", "s", property_get_description, 0, SD_BUS_VTABLE_PROPERTY_CONST),
@ -2237,7 +2238,7 @@ static int bus_unit_set_transient_property(
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Unit name '%s' is not a slice", s);
if (!UNIT_WRITE_FLAGS_NOOP(flags)) {
r = unit_set_slice(u, slice);
r = unit_set_slice(u, slice, UNIT_DEPENDENCY_FILE);
if (r < 0)
return r;

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@ -3574,7 +3574,7 @@ int config_parse_unit_slice(
return 0;
}
r = unit_set_slice(u, slice);
r = unit_set_slice(u, slice, UNIT_DEPENDENCY_FILE);
if (r < 0) {
log_syntax(unit, LOG_WARNING, filename, line, r, "Failed to assign slice %s to unit %s, ignoring: %m", slice->id, u->id);
return 0;

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@ -47,7 +47,7 @@ static void slice_set_state(Slice *t, SliceState state) {
}
static int slice_add_parent_slice(Slice *s) {
Unit *u = UNIT(s), *parent;
Unit *u = UNIT(s);
_cleanup_free_ char *a = NULL;
int r;
@ -60,12 +60,7 @@ static int slice_add_parent_slice(Slice *s) {
if (r <= 0) /* 0 means root slice */
return r;
r = manager_load_unit(u->manager, a, NULL, NULL, &parent);
if (r < 0)
return r;
unit_ref_set(&u->slice, u, parent);
return 0;
return unit_add_dependency_by_name(u, UNIT_IN_SLICE, a, true, UNIT_DEPENDENCY_IMPLICIT);
}
static int slice_add_default_dependencies(Slice *s) {
@ -346,14 +341,11 @@ static void slice_enumerate_perpetual(Manager *m) {
static bool slice_freezer_action_supported_by_children(Unit *s) {
Unit *member;
int r;
assert(s);
UNIT_FOREACH_DEPENDENCY(member, s, UNIT_ATOM_BEFORE) {
int r;
if (UNIT_DEREF(member->slice) != s)
continue;
UNIT_FOREACH_DEPENDENCY(member, s, UNIT_ATOM_SLICE_OF) {
if (member->type == UNIT_SLICE) {
r = slice_freezer_action_supported_by_children(member);
@ -380,10 +372,7 @@ static int slice_freezer_action(Unit *s, FreezerAction action) {
return 0;
}
UNIT_FOREACH_DEPENDENCY(member, s, UNIT_ATOM_BEFORE) {
if (UNIT_DEREF(member->slice) != s)
continue;
UNIT_FOREACH_DEPENDENCY(member, s, UNIT_ATOM_SLICE_OF) {
if (action == FREEZER_FREEZE)
r = UNIT_VTABLE(member)->freeze(member);
else

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@ -78,6 +78,8 @@ static const UnitDependencyAtom atom_map[_UNIT_DEPENDENCY_MAX] = {
[UNIT_JOINS_NAMESPACE_OF] = UNIT_ATOM_JOINS_NAMESPACE_OF,
[UNIT_REFERENCES] = UNIT_ATOM_REFERENCES,
[UNIT_REFERENCED_BY] = UNIT_ATOM_REFERENCED_BY,
[UNIT_IN_SLICE] = UNIT_ATOM_IN_SLICE,
[UNIT_SLICE_OF] = UNIT_ATOM_SLICE_OF,
/* These are dependency types without effect on our state engine. We maintain them only to make
* things discoverable/debuggable as they are the inverse dependencies to some of the above. As they
@ -190,6 +192,12 @@ UnitDependency unit_dependency_from_unique_atom(UnitDependencyAtom atom) {
case UNIT_ATOM_REFERENCED_BY:
return UNIT_REFERENCED_BY;
case UNIT_ATOM_IN_SLICE:
return UNIT_IN_SLICE;
case UNIT_ATOM_SLICE_OF:
return UNIT_SLICE_OF;
default:
return _UNIT_DEPENDENCY_INVALID;
}

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@ -69,7 +69,9 @@ typedef enum UnitDependencyAtom {
UNIT_ATOM_JOINS_NAMESPACE_OF = UINT64_C(1) << 29,
UNIT_ATOM_REFERENCES = UINT64_C(1) << 30,
UNIT_ATOM_REFERENCED_BY = UINT64_C(1) << 31,
_UNIT_DEPENDENCY_ATOM_MAX = (UINT64_C(1) << 32) - 1,
UNIT_ATOM_IN_SLICE = UINT64_C(1) << 32,
UNIT_ATOM_SLICE_OF = UINT64_C(1) << 33,
_UNIT_DEPENDENCY_ATOM_MAX = (UINT64_C(1) << 34) - 1,
_UNIT_DEPENDENCY_ATOM_INVALID = -EINVAL,
} UnitDependencyAtom;

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@ -659,11 +659,10 @@ Unit* unit_free(Unit *u) {
job_free(j);
}
unit_clear_dependencies(u);
/* A unit is being dropped from the tree, make sure our family is realized properly. Do this after we
* detach the unit from slice tree in order to eliminate its effect on controller masks. */
slice = UNIT_GET_SLICE(u);
unit_clear_dependencies(u);
if (slice)
unit_add_family_to_cgroup_realize_queue(slice);
@ -689,7 +688,6 @@ Unit* unit_free(Unit *u) {
unit_unwatch_all_pids(u);
unit_ref_unset(&u->slice);
while (u->refs_by_target)
unit_ref_unset(u->refs_by_target);
@ -2881,6 +2879,8 @@ int unit_add_dependency(
[UNIT_PROPAGATES_RELOAD_TO] = UNIT_RELOAD_PROPAGATED_FROM,
[UNIT_RELOAD_PROPAGATED_FROM] = UNIT_PROPAGATES_RELOAD_TO,
[UNIT_JOINS_NAMESPACE_OF] = UNIT_JOINS_NAMESPACE_OF, /* symmetric! 👓 */
[UNIT_IN_SLICE] = UNIT_SLICE_OF,
[UNIT_SLICE_OF] = UNIT_IN_SLICE,
};
Unit *original_u = u, *original_other = other;
UnitDependencyAtom a;
@ -2924,6 +2924,21 @@ int unit_add_dependency(
return log_unit_error_errno(u, SYNTHETIC_ERRNO(EINVAL),
"Requested dependency TriggeredBy=%s refused (%s units cannot trigger other units).", other->id, unit_type_to_string(other->type));
if (FLAGS_SET(a, UNIT_ATOM_IN_SLICE) && other->type != UNIT_SLICE)
return log_unit_error_errno(u, SYNTHETIC_ERRNO(EINVAL),
"Requested dependency Slice=%s refused (%s is not a slice unit).", other->id, other->id);
if (FLAGS_SET(a, UNIT_ATOM_SLICE_OF) && u->type != UNIT_SLICE)
return log_unit_error_errno(u, SYNTHETIC_ERRNO(EINVAL),
"Requested dependency SliceOf=%s refused (%s is not a slice unit).", other->id, u->id);
if (FLAGS_SET(a, UNIT_ATOM_IN_SLICE) && !UNIT_HAS_CGROUP_CONTEXT(u))
return log_unit_error_errno(u, SYNTHETIC_ERRNO(EINVAL),
"Requested dependency Slice=%s refused (%s is not a cgroup unit).", other->id, u->id);
if (FLAGS_SET(a, UNIT_ATOM_SLICE_OF) && !UNIT_HAS_CGROUP_CONTEXT(other))
return log_unit_error_errno(u, SYNTHETIC_ERRNO(EINVAL),
"Requested dependency SliceOf=%s refused (%s is not a cgroup unit).", other->id, other->id);
r = unit_add_dependency_hashmap(&u->dependencies, d, other, mask, 0);
if (r < 0)
return r;
@ -3102,15 +3117,15 @@ reset:
return r;
}
int unit_set_slice(Unit *u, Unit *slice) {
int unit_set_slice(Unit *u, Unit *slice, UnitDependencyMask mask) {
int r;
assert(u);
assert(slice);
/* Sets the unit slice if it has not been set before. Is extra
* careful, to only allow this for units that actually have a
* cgroup context. Also, we don't allow to set this for slices
* (since the parent slice is derived from the name). Make
* sure the unit we set is actually a slice. */
/* Sets the unit slice if it has not been set before. Is extra careful, to only allow this for units
* that actually have a cgroup context. Also, we don't allow to set this for slices (since the parent
* slice is derived from the name). Make sure the unit we set is actually a slice. */
if (!UNIT_HAS_CGROUP_CONTEXT(u))
return -EOPNOTSUPP;
@ -3135,7 +3150,10 @@ int unit_set_slice(Unit *u, Unit *slice) {
if (UNIT_GET_SLICE(u) && u->cgroup_realized)
return -EBUSY;
unit_ref_set(&u->slice, u, slice);
r = unit_add_dependency(u, UNIT_IN_SLICE, slice, true, mask);
if (r < 0)
return r;
return 1;
}
@ -3185,7 +3203,7 @@ int unit_set_default_slice(Unit *u) {
if (r < 0)
return r;
return unit_set_slice(u, slice);
return unit_set_slice(u, slice, UNIT_DEPENDENCY_FILE);
}
const char *unit_slice_name(Unit *u) {

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@ -202,8 +202,6 @@ typedef struct Unit {
dual_timestamp active_exit_timestamp;
dual_timestamp inactive_enter_timestamp;
UnitRef slice;
/* Per type list */
LIST_FIELDS(Unit, units_by_type);
@ -707,8 +705,7 @@ static inline Unit* UNIT_TRIGGER(Unit *u) {
}
static inline Unit* UNIT_GET_SLICE(const Unit *u) {
assert(u);
return u->slice.target;
return unit_has_dependency(u, UNIT_ATOM_IN_SLICE, NULL);
}
Unit* unit_new(Manager *m, size_t size);
@ -751,7 +748,7 @@ Unit *unit_follow_merge(Unit *u) _pure_;
int unit_load_fragment_and_dropin(Unit *u, bool fragment_required);
int unit_load(Unit *unit);
int unit_set_slice(Unit *u, Unit *slice);
int unit_set_slice(Unit *u, Unit *slice, UnitDependencyMask mask);
int unit_set_default_slice(Unit *u);
const char *unit_description(Unit *u) _pure_;