Merge pull request #13512 from msekletar/freezer

core: introduce support for cgroup freezer

src/basic/cgroup-util.c

@@ -149,6 +149,17 @@ bool cg_ns_supported(void) {
         return enabled;
 }
 
+bool cg_freezer_supported(void) {
+        static thread_local int supported = -1;
+
+        if (supported >= 0)
+                return supported;
+
+        supported = cg_all_unified() > 0 && access("/sys/fs/cgroup/init.scope/cgroup.freeze", F_OK) == 0;
+
+        return supported;
+}
+
 int cg_enumerate_subgroups(const char *controller, const char *path, DIR **_d) {
         _cleanup_free_ char *fs = NULL;
         int r;
@@ -1684,12 +1695,13 @@ int cg_get_attribute_as_uint64(const char *controller, const char *path, const c
         return 0;
 }
 
-int cg_get_keyed_attribute(
+int cg_get_keyed_attribute_full(
                 const char *controller,
                 const char *path,
                 const char *attribute,
                 char **keys,
-                char **ret_values) {
+                char **ret_values,
+                CGroupKeyMode mode) {
 
         _cleanup_free_ char *filename = NULL, *contents = NULL;
         const char *p;
@@ -1701,7 +1713,8 @@ int cg_get_keyed_attribute(
          * all keys to retrieve. The 'ret_values' parameter should be passed as string size with the same number of
          * entries as 'keys'. On success each entry will be set to the value of the matching key.
          *
-         * If the attribute file doesn't exist at all returns ENOENT, if any key is not found returns ENXIO. */
+         * If the attribute file doesn't exist at all returns ENOENT, if any key is not found returns ENXIO. If mode
+         * is set to GG_KEY_MODE_GRACEFUL we ignore missing keys and return those that were parsed successfully. */
 
         r = cg_get_path(controller, path, attribute, &filename);
         if (r < 0)
@@ -1749,6 +1762,9 @@ int cg_get_keyed_attribute(
                 p += strspn(p, NEWLINE);
         }
 
+        if (mode & CG_KEY_MODE_GRACEFUL)
+                goto done;
+
         r = -ENXIO;
 
 fail:
@@ -1759,6 +1775,9 @@ fail:
 
 done:
         memcpy(ret_values, v, sizeof(char*) * n);
+        if (mode & CG_KEY_MODE_GRACEFUL)
+                return n_done;
+
         return 0;
 }
 

src/basic/cgroup-util.h

@@ -180,9 +180,31 @@ int cg_pid_get_path(const char *controller, pid_t pid, char **path);
 
 int cg_rmdir(const char *controller, const char *path);
 
+typedef enum  {
+        CG_KEY_MODE_GRACEFUL = 1 << 0,
+} CGroupKeyMode;
+
 int cg_set_attribute(const char *controller, const char *path, const char *attribute, const char *value);
 int cg_get_attribute(const char *controller, const char *path, const char *attribute, char **ret);
-int cg_get_keyed_attribute(const char *controller, const char *path, const char *attribute, char **keys, char **values);
+int cg_get_keyed_attribute_full(const char *controller, const char *path, const char *attribute, char **keys, char **values, CGroupKeyMode mode);
+
+static inline int cg_get_keyed_attribute(
+                const char *controller,
+                const char *path,
+                const char *attribute,
+                char **keys,
+                char **ret_values) {
+        return cg_get_keyed_attribute_full(controller, path, attribute, keys, ret_values, 0);
+}
+
+static inline int cg_get_keyed_attribute_graceful(
+                const char *controller,
+                const char *path,
+                const char *attribute,
+                char **keys,
+                char **ret_values) {
+        return cg_get_keyed_attribute_full(controller, path, attribute, keys, ret_values, CG_KEY_MODE_GRACEFUL);
+}
 
 int cg_get_attribute_as_uint64(const char *controller, const char *path, const char *attribute, uint64_t *ret);
 
@@ -238,6 +260,7 @@ int cg_mask_to_string(CGroupMask mask, char **ret);
 int cg_kernel_controllers(Set **controllers);
 
 bool cg_ns_supported(void);
+bool cg_freezer_supported(void);
 
 int cg_all_unified(void);
 int cg_hybrid_unified(void);

src/basic/unit-def.c

@@ -108,6 +108,15 @@ static const char* const unit_active_state_table[_UNIT_ACTIVE_STATE_MAX] = {
 
 DEFINE_STRING_TABLE_LOOKUP(unit_active_state, UnitActiveState);
 
+static const char* const freezer_state_table[_FREEZER_STATE_MAX] = {
+        [FREEZER_RUNNING] = "running",
+        [FREEZER_FREEZING] = "freezing",
+        [FREEZER_FROZEN] = "frozen",
+        [FREEZER_THAWING] = "thawing",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(freezer_state, FreezerState);
+
 static const char* const automount_state_table[_AUTOMOUNT_STATE_MAX] = {
         [AUTOMOUNT_DEAD] = "dead",
         [AUTOMOUNT_WAITING] = "waiting",

src/basic/unit-def.h

@@ -48,6 +48,15 @@ typedef enum UnitActiveState {
         _UNIT_ACTIVE_STATE_INVALID = -1
 } UnitActiveState;
 
+typedef enum FreezerState {
+        FREEZER_RUNNING,
+        FREEZER_FREEZING,
+        FREEZER_FROZEN,
+        FREEZER_THAWING,
+        _FREEZER_STATE_MAX,
+        _FREEZER_STATE_INVALID = -1
+} FreezerState;
+
 typedef enum AutomountState {
         AUTOMOUNT_DEAD,
         AUTOMOUNT_WAITING,
@@ -253,6 +262,9 @@ UnitLoadState unit_load_state_from_string(const char *s) _pure_;
 const char *unit_active_state_to_string(UnitActiveState i) _const_;
 UnitActiveState unit_active_state_from_string(const char *s) _pure_;
 
+const char *freezer_state_to_string(FreezerState i) _const_;
+FreezerState freezer_state_from_string(const char *s) _pure_;
+
 const char* automount_state_to_string(AutomountState i) _const_;
 AutomountState automount_state_from_string(const char *s) _pure_;