src: Introduce virCgroupFreezerState enum

So far, only vircgroupv1 implements freezer controller related
callbacks and both work with strings ("THAWED", "FROZEN",
"FREEZING"). This works well with v1 but with CGroupsV2 there are
just two states and they are represented by a number.

Therefore, introduce an enum and implement enum <-> string
conversion for each backend separately.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Pavel Hrdina <pavel@hrdina.info>

src/lxc/lxc_driver.c

@@ -2495,11 +2495,12 @@ static int lxcFreezeContainer(virDomainObj *vm)
     int check_interval = 1; /* In milliseconds */
     int exp = 10;
     int waited_time = 0;
-    g_autofree char *state = NULL;
     virLXCDomainObjPrivate *priv = vm->privateData;
 
     while (waited_time < timeout) {
+        virCgroupFreezerState state;
         int r;
+
         /*
          * Writing "FROZEN" to the "freezer.state" freezes the group,
          * i.e., the container, temporarily transiting "FREEZING" state.
@@ -2507,7 +2508,8 @@ static int lxcFreezeContainer(virDomainObj *vm)
          * to "FROZEN".
          * (see linux-2.6/Documentation/cgroups/freezer-subsystem.txt)
          */
-        r = virCgroupSetFreezerState(priv->cgroup, "FROZEN");
+        r = virCgroupSetFreezerState(priv->cgroup,
+                                     VIR_CGROUP_FREEZER_STATE_FROZEN);
 
         /*
          * Returning EBUSY explicitly indicates that the group is
@@ -2540,9 +2542,9 @@ static int lxcFreezeContainer(virDomainObj *vm)
             VIR_DEBUG("Reading freezer.state failed with errno: %d", r);
             goto error;
         }
-        VIR_DEBUG("Read freezer.state: %s", state);
+        VIR_DEBUG("Read freezer.state: %d", state);
 
-        if (STREQ(state, "FROZEN"))
+        if (state == VIR_CGROUP_FREEZER_STATE_FROZEN)
             return 0;
 
         waited_time += check_interval;
@@ -2563,7 +2565,7 @@ static int lxcFreezeContainer(virDomainObj *vm)
      * activate the group again and return an error.
      * This is likely to fall the group back again gracefully.
      */
-    virCgroupSetFreezerState(priv->cgroup, "THAWED");
+    virCgroupSetFreezerState(priv->cgroup, VIR_CGROUP_FREEZER_STATE_THAWED);
     return -1;
 }
 
@@ -2643,7 +2645,8 @@ static int lxcDomainResume(virDomainPtr dom)
                        "%s", _("domain is already running"));
         goto endjob;
     } else if (state == VIR_DOMAIN_PAUSED) {
-        if (virCgroupSetFreezerState(priv->cgroup, "THAWED") < 0) {
+        if (virCgroupSetFreezerState(priv->cgroup,
+                                     VIR_CGROUP_FREEZER_STATE_THAWED) < 0) {
             virReportError(VIR_ERR_OPERATION_FAILED,
                            "%s", _("Resume operation failed"));
             goto endjob;

src/lxc/lxc_process.c

@@ -860,7 +860,8 @@ int virLXCProcessStop(virLXCDriver *driver,
             return -1;
         }
 
-        if (virCgroupSetFreezerState(priv->cgroup, "THAWED") < 0) {
+        if (virCgroupSetFreezerState(priv->cgroup,
+                                     VIR_CGROUP_FREEZER_STATE_THAWED) < 0) {
             virReportError(VIR_ERR_OPERATION_FAILED, "%s",
                            _("Unable to thaw all processes"));
 

src/util/vircgroup.c

@@ -2902,7 +2902,8 @@ virCgroupGetCpuacctStat(virCgroup *group, unsigned long long *user,
 
 
 int
-virCgroupSetFreezerState(virCgroup *group, const char *state)
+virCgroupSetFreezerState(virCgroup *group,
+                         virCgroupFreezerState state)
 {
     virCgroup *parent = virCgroupGetNested(group);
 
@@ -2912,7 +2913,8 @@ virCgroupSetFreezerState(virCgroup *group, const char *state)
 
 
 int
-virCgroupGetFreezerState(virCgroup *group, char **state)
+virCgroupGetFreezerState(virCgroup *group,
+                         virCgroupFreezerState *state)
 {
     virCgroup *parent = virCgroupGetNested(group);
 
@@ -3725,7 +3727,7 @@ virCgroupGetDomainTotalCpuStats(virCgroup *group G_GNUC_UNUSED,
 
 int
 virCgroupSetFreezerState(virCgroup *group G_GNUC_UNUSED,
-                         const char *state G_GNUC_UNUSED)
+                         virCgroupFreezerState state G_GNUC_UNUSED)
 {
     virReportSystemError(ENOSYS, "%s",
                          _("Control groups not supported on this platform"));
@@ -3735,7 +3737,7 @@ virCgroupSetFreezerState(virCgroup *group G_GNUC_UNUSED,
 
 int
 virCgroupGetFreezerState(virCgroup *group G_GNUC_UNUSED,
-                         char **state G_GNUC_UNUSED)
+                         virCgroupFreezerState **state G_GNUC_UNUSED)
 {
     virReportSystemError(ENOSYS, "%s",
                          _("Control groups not supported on this platform"));

src/util/vircgroup.h

@@ -254,8 +254,16 @@ int virCgroupGetCpuacctPercpuUsage(virCgroup *group, char **usage);
 int virCgroupGetCpuacctStat(virCgroup *group, unsigned long long *user,
                             unsigned long long *sys);
 
-int virCgroupSetFreezerState(virCgroup *group, const char *state);
-int virCgroupGetFreezerState(virCgroup *group, char **state);
+typedef enum {
+    VIR_CGROUP_FREEZER_STATE_THAWED,
+    VIR_CGROUP_FREEZER_STATE_FROZEN,
+    VIR_CGROUP_FREEZER_STATE_FREEZING,
+
+    VIR_CGROUP_FREEZER_STATE_LAST
+} virCgroupFreezerState;
+
+int virCgroupSetFreezerState(virCgroup *group, virCgroupFreezerState state);
+int virCgroupGetFreezerState(virCgroup *group, virCgroupFreezerState *state);
 
 int virCgroupSetCpusetMems(virCgroup *group, const char *mems);
 int virCgroupGetCpusetMems(virCgroup *group, char **mems);

src/util/vircgroupbackend.h

@@ -339,11 +339,11 @@ typedef int
 
 typedef int
 (*virCgroupSetFreezerStateCB)(virCgroup *group,
-                              const char *state);
+                              virCgroupFreezerState state);
 
 typedef int
 (*virCgroupGetFreezerStateCB)(virCgroup *group,
-                              char **state);
+                              virCgroupFreezerState *state);
 
 typedef int
 (*virCgroupSetCpusetMemsCB)(virCgroup *group,

src/util/vircgroupv1.c

@@ -2049,23 +2049,49 @@ virCgroupV1GetCpuacctStat(virCgroup *group,
 }
 
 
+VIR_ENUM_DECL(virCgroupFreezerState);
+VIR_ENUM_IMPL(virCgroupFreezerState,
+              VIR_CGROUP_FREEZER_STATE_LAST,
+              "THAWED",
+              "FROZEN",
+              "FREEZING"
+);
+
 static int
 virCgroupV1SetFreezerState(virCgroup *group,
-                           const char *state)
+                           virCgroupFreezerState state)
 {
+    const char *stateStr = virCgroupFreezerStateTypeToString(state);
+
     return virCgroupSetValueStr(group,
                                 VIR_CGROUP_CONTROLLER_FREEZER,
-                                "freezer.state", state);
+                                "freezer.state", stateStr);
 }
 
 
 static int
 virCgroupV1GetFreezerState(virCgroup *group,
-                           char **state)
+                           virCgroupFreezerState *state)
 {
-    return virCgroupGetValueStr(group,
-                                VIR_CGROUP_CONTROLLER_FREEZER,
-                                "freezer.state", state);
+    g_autofree char *stateStr = NULL;
+    int s;
+
+    if (virCgroupGetValueStr(group,
+                             VIR_CGROUP_CONTROLLER_FREEZER,
+                             "freezer.state", &stateStr) < 0) {
+        return -1;
+    }
+
+    s = virCgroupFreezerStateTypeFromString(stateStr);
+    if (s < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Unknown value of freezer controller: %1$s"),
+                       stateStr);
+        return -1;
+    }
+
+    *state = s;
+    return 0;
 }