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shared/condition: add ConditionControlGroupController=v1|v2

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Before, we only allowed conditionalizing on controllers, not the hierarchy.
This commit extends this to allow a simple check for v1 (i.e. classic or hybrid),
and v2 (full unified).

An alternative approach would be to add a separate Condition for this, but I'm
not too keen on that, considering that v1 is already being deprecrecated
(c.f. 82f3063218).
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2021-02-22 22:09:38 +01:00
parent 6c3f7ca036
commit 8ebfd50aaf
3 changed files with 47 additions and 10 deletions
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27
man/systemd.unit.xml
View file

@ -1456,14 +1456,25 @@
<varlistentry>
<term><varname>ConditionControlGroupController=</varname></term>
<listitem><para>Verify that the given cgroup controller (eg. <literal>cpu</literal>) is available
for use on the system. For example, a particular controller may not be available if it was disabled
on the kernel command line with <varname>cgroup_disable=controller</varname>. Multiple controllers
may be passed with a space separating them; in this case the condition will only pass if all listed
controllers are available for use. Controllers unknown to systemd are ignored. Valid controllers
are <literal>cpu</literal>, <literal>cpuacct</literal>, <literal>io</literal>,
<literal>blkio</literal>, <literal>memory</literal>, <literal>devices</literal>, and
<literal>pids</literal>.</para>
<listitem><para>Check whether given cgroup controllers (eg. <literal>cpu</literal>) are available
for use on the system or whether the legacy v1 cgroup or the modern v2 cgroup hierarchy is used.
</para>
<para>Multiple controllers may be passed with a space separating them; in this case the condition
will only pass if all listed controllers are available for use. Controllers unknown to systemd are
ignored. Valid controllers are <literal>cpu</literal>, <literal>cpuacct</literal>,
<literal>io</literal>, <literal>blkio</literal>, <literal>memory</literal>,
<literal>devices</literal>, and <literal>pids</literal>. Even if available in the kernel, a
particular controller may not be available if it was disabled on the kernel command line with
<varname>cgroup_disable=controller</varname>.</para>
<para>Alternatively, two special strings <literal>v1</literal> and <literal>v2</literal> may be
specified (without any controller names). <literal>v2</literal> will pass if the unified v2 cgroup
hierachy is used, and <literal>v1</literal> will pass if the legacy v1 hierarchy or the hybrid
hierarchy are used (see the discussion of <varname>systemd.unified_cgroup_hierarchy</varname> and
<varname>systemd.legacy_systemd_cgroup_controller</varname> in
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for more information).</para>
</listitem>
</varlistentry>

9
src/shared/condition.c
View file

@ -354,6 +354,15 @@ static int condition_test_control_group_controller(Condition *c, char **env) {
assert(c->parameter);
assert(c->type == CONDITION_CONTROL_GROUP_CONTROLLER);
if (streq(c->parameter, "v2"))
return cg_all_unified();
if (streq(c->parameter, "v1")) {
r = cg_all_unified();
if (r < 0)
return r;
return !r;
}
r = cg_mask_supported(&system_mask);
if (r < 0)
return log_debug_errno(r, "Failed to determine supported controllers: %m");

21
src/test/test-condition.c
View file

@ -124,10 +124,26 @@ static void test_condition_test_path(void) {
condition_free(condition);
}
static void test_condition_test_control_group_hierarchy(void) {
Condition *condition;
int r;
r = cg_unified();
condition = condition_new(CONDITION_CONTROL_GROUP_CONTROLLER, "v1", false, false);
assert_se(condition);
assert_se(condition_test(condition, environ) == (r < CGROUP_UNIFIED_ALL));
condition_free(condition);
condition = condition_new(CONDITION_CONTROL_GROUP_CONTROLLER, "v2", false, false);
assert_se(condition);
assert_se(condition_test(condition, environ) == (r >= CGROUP_UNIFIED_ALL));
condition_free(condition);
}
static void test_condition_test_control_group_controller(void) {
Condition *condition;
CGroupMask system_mask;
CGroupController controller;
_cleanup_free_ char *controller_name = NULL;
int r;
@ -151,7 +167,7 @@ static void test_condition_test_control_group_controller(void) {
assert_se(cg_mask_supported(&system_mask) >= 0);
/* Individual valid controllers one by one */
for (controller = 0; controller < _CGROUP_CONTROLLER_MAX; controller++) {
for (CGroupController controller = 0; controller < _CGROUP_CONTROLLER_MAX; controller++) {
const char *local_controller_name = cgroup_controller_to_string(controller);
log_info("chosen controller is '%s'", local_controller_name);
if (system_mask & CGROUP_CONTROLLER_TO_MASK(controller)) {
@ -881,6 +897,7 @@ int main(int argc, char *argv[]) {
test_condition_test_virtualization();
test_condition_test_user();
test_condition_test_group();
test_condition_test_control_group_hierarchy();
test_condition_test_control_group_controller();
test_condition_test_cpus();
test_condition_test_memory();