basic/cgroup-util: let cgroup_unified_flush() return the detected hierarchy

This avoid the use of the global variable.

Also rename cgroup_unified_update() to cgroup_unified_cached() and
cgroup_unified_flush() to cgroup_unified() to better reflect their new roles.

diff --git a/src/basic/cgroup-util.c b/src/basic/cgroup-util.c
index 7b5839ccd6088ec12dab399ae99527f5b00d96dc..2865cd518ef465120145006226d7a125bde24115 100644 (file)
--- a/src/basic/cgroup-util.c
+++ b/src/basic/cgroup-util.c
@@ -2526,20 +2526,20 @@ int cg_kernel_controllers(Set **ret) {
         return 0;
 }
 
-static thread_local CGroupUnified unified_cache = CGROUP_UNIFIED_UNKNOWN;
-
-/* The hybrid mode was initially implemented in v232 and simply mounted cgroup2 on /sys/fs/cgroup/systemd.  This
- * unfortunately broke other tools (such as docker) which expected the v1 "name=systemd" hierarchy on
- * /sys/fs/cgroup/systemd.  From v233 and on, the hybrid mode mountnbs v2 on /sys/fs/cgroup/unified and maintains
- * "name=systemd" hierarchy on /sys/fs/cgroup/systemd for compatibility with other tools.
+/* The hybrid mode was initially implemented in v232 and simply mounted cgroup2 on
+ * /sys/fs/cgroup/systemd. This unfortunately broke other tools (such as docker) which expected the v1
+ * "name=systemd" hierarchy on /sys/fs/cgroup/systemd. From v233 and on, the hybrid mode mounts v2 on
+ * /sys/fs/cgroup/unified and maintains "name=systemd" hierarchy on /sys/fs/cgroup/systemd for compatibility
+ * with other tools.
  *
- * To keep live upgrade working, we detect and support v232 layout.  When v232 layout is detected, to keep cgroup v2
- * process management but disable the compat dual layout, we return %true on
- * cg_unified_controller(SYSTEMD_CGROUP_CONTROLLER) and %false on cg_hybrid_unified().
+ * To keep live upgrade working, we detect and support v232 layout. When v232 layout is detected, to keep
+ * cgroup v2 process management but disable the compat dual layout, we return true on
+ * cg_unified_controller(SYSTEMD_CGROUP_CONTROLLER) and false on cg_hybrid_unified().
  */
 static thread_local bool unified_systemd_v232;
 
-static int cg_unified_update(void) {
+int cg_unified_cached(bool flush) {
+        static thread_local CGroupUnified unified_cache = CGROUP_UNIFIED_UNKNOWN;
 
         struct statfs fs;
 
@@ -2548,8 +2548,10 @@ static int cg_unified_update(void) {
          * have any other trouble determining if the unified hierarchy
          * is supported. */
 
-        if (unified_cache >= CGROUP_UNIFIED_NONE)
-                return 0;
+        if (flush)
+                unified_cache = CGROUP_UNIFIED_UNKNOWN;
+        else if (unified_cache >= CGROUP_UNIFIED_NONE)
+                return unified_cache;
 
         if (statfs("/sys/fs/cgroup/", &fs) < 0)
                 return log_debug_errno(errno, "statfs(\"/sys/fs/cgroup/\") failed: %m");
@@ -2585,20 +2587,20 @@ static int cg_unified_update(void) {
                                        "Unknown filesystem type %llx mounted on /sys/fs/cgroup.",
                                        (unsigned long long)fs.f_type);
 
-        return 0;
+        return unified_cache;
 }
 
 int cg_unified_controller(const char *controller) {
         int r;
 
-        r = cg_unified_update();
+        r = cg_unified_cached(false);
         if (r < 0)
                 return r;
 
-        if (unified_cache == CGROUP_UNIFIED_NONE)
+        if (r == CGROUP_UNIFIED_NONE)
                 return false;
 
-        if (unified_cache >= CGROUP_UNIFIED_ALL)
+        if (r >= CGROUP_UNIFIED_ALL)
                 return true;
 
         return streq_ptr(controller, SYSTEMD_CGROUP_CONTROLLER);
@@ -2607,27 +2609,21 @@ int cg_unified_controller(const char *controller) {
 int cg_all_unified(void) {
         int r;
 
-        r = cg_unified_update();
+        r = cg_unified_cached(false);
         if (r < 0)
                 return r;
 
-        return unified_cache >= CGROUP_UNIFIED_ALL;
+        return r >= CGROUP_UNIFIED_ALL;
 }
 
 int cg_hybrid_unified(void) {
         int r;
 
-        r = cg_unified_update();
+        r = cg_unified_cached(false);
         if (r < 0)
                 return r;
 
-        return unified_cache == CGROUP_UNIFIED_SYSTEMD && !unified_systemd_v232;
-}
-
-int cg_unified_flush(void) {
-        unified_cache = CGROUP_UNIFIED_UNKNOWN;
-
-        return cg_unified_update();
+        return r == CGROUP_UNIFIED_SYSTEMD && !unified_systemd_v232;
 }
 
 int cg_enable_everywhere(
@@ -2740,10 +2736,10 @@ int cg_enable_everywhere(
 
 bool cg_is_unified_wanted(void) {
         static thread_local int wanted = -1;
-        int r;
         bool b;
         const bool is_default = DEFAULT_HIERARCHY == CGROUP_UNIFIED_ALL;
         _cleanup_free_ char *c = NULL;
+        int r;
 
         /* If we have a cached value, return that. */
         if (wanted >= 0)
@@ -2751,8 +2747,9 @@ bool cg_is_unified_wanted(void) {
 
         /* If the hierarchy is already mounted, then follow whatever
          * was chosen for it. */
-        if (cg_unified_flush() >= 0)
-                return (wanted = unified_cache >= CGROUP_UNIFIED_ALL);
+        r = cg_unified_cached(true);
+        if (r >= 0)
+                return (wanted = r >= CGROUP_UNIFIED_ALL);
 
         /* If we were explicitly passed systemd.unified_cgroup_hierarchy,
          * respect that. */
@@ -2777,8 +2774,7 @@ bool cg_is_legacy_wanted(void) {
                 return wanted;
 
         /* Check if we have cgroup v2 already mounted. */
-        if (cg_unified_flush() >= 0 &&
-            unified_cache == CGROUP_UNIFIED_ALL)
+        if (cg_unified_cached(true) == CGROUP_UNIFIED_ALL)
                 return (wanted = false);
 
         /* Otherwise, assume that at least partial legacy is wanted,
@@ -2801,8 +2797,7 @@ bool cg_is_hybrid_wanted(void) {
 
         /* If the hierarchy is already mounted, then follow whatever
          * was chosen for it. */
-        if (cg_unified_flush() >= 0 &&
-            unified_cache == CGROUP_UNIFIED_ALL)
+        if (cg_unified_cached(true) == CGROUP_UNIFIED_ALL)
                 return (wanted = false);
 
         /* Otherwise, let's see what the kernel command line has to say.

diff --git a/src/basic/cgroup-util.h b/src/basic/cgroup-util.h
index a39ab451b9542b15a428668014c6c0dace32d503..ba8df8139d161ee7b2670f3d761556e194c76d40 100644 (file)
--- a/src/basic/cgroup-util.h
+++ b/src/basic/cgroup-util.h
@@ -258,7 +258,10 @@ bool cg_ns_supported(void);
 int cg_all_unified(void);
 int cg_hybrid_unified(void);
 int cg_unified_controller(const char *controller);
-int cg_unified_flush(void);
+int cg_unified_cached(bool flush);
+static inline int cg_unified(void) {
+        return cg_unified_cached(true);
+}
 
 bool cg_is_unified_wanted(void);
 bool cg_is_legacy_wanted(void);

diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index 60a77993616ee05cc32069cc8d8b5a888c44b2be..7b0a41fbc8cf8df1e4e610550efc5d66118319b5 100644 (file)
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -2839,7 +2839,7 @@ int manager_setup_cgroup(Manager *m) {
         if (r < 0)
                 return log_error_errno(r, "Cannot find cgroup mount point: %m");
 
-        r = cg_unified_flush();
+        r = cg_unified();
         if (r < 0)
                 return log_error_errno(r, "Couldn't determine if we are running in the unified hierarchy: %m");
 

diff --git a/src/libsystemd/sd-bus/test-bus-creds.c b/src/libsystemd/sd-bus/test-bus-creds.c
index c02c459663b883f68c7c652704f274df9859b0b6..7f7bc491d2586faf050141d7f386d284060a38e3 100644 (file)
--- a/src/libsystemd/sd-bus/test-bus-creds.c
+++ b/src/libsystemd/sd-bus/test-bus-creds.c
@@ -13,7 +13,7 @@ int main(int argc, char *argv[]) {
 
         test_setup_logging(LOG_DEBUG);
 
-        if (cg_unified_flush() == -ENOMEDIUM)
+        if (cg_unified() == -ENOMEDIUM)
                 return log_tests_skipped("/sys/fs/cgroup/ not available");
 
         r = sd_bus_creds_new_from_pid(&creds, 0, _SD_BUS_CREDS_ALL);

diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index 2aec8041f007923a6c27719aa65b8a25210ff3a8..91ec61402b70472771a7ff9562ae2feb83d8d510 100644 (file)
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -4720,7 +4720,7 @@ static int run(int argc, char *argv[]) {
         if (r < 0)
                 goto finish;
 
-        r = cg_unified_flush();
+        r = cg_unified();
         if (r < 0) {
                 log_error_errno(r, "Failed to determine whether the unified cgroups hierarchy is used: %m");
                 goto finish;

diff --git a/src/test/test-cgroup-util.c b/src/test/test-cgroup-util.c
index b54b5e76c67a92a23895fe1cde26b906571df16d..f45c5ff760f5cb770551153384ff732012a68b51 100644 (file)
--- a/src/test/test-cgroup-util.c
+++ b/src/test/test-cgroup-util.c
@@ -385,12 +385,12 @@ static void test_is_wanted(void) {
 static void test_cg_tests(void) {
         int all, hybrid, systemd, r;
 
-        r = cg_unified_flush();
+        r = cg_unified();
         if (r == -ENOMEDIUM) {
                 log_notice_errno(r, "Skipping cg hierarchy tests: %m");
                 return;
         }
-        assert_se(r == 0);
+        assert_se(r >= 0);
 
         all = cg_all_unified();
         assert_se(IN_SET(all, 0, 1));

diff --git a/src/test/test-condition.c b/src/test/test-condition.c
index a79263a50bf94f4e78352c3ef51f19f90609fc58..9a0a4cfee21fbaaa3f14ff01fc5df5b81eb10c2f 100644 (file)
--- a/src/test/test-condition.c
+++ b/src/test/test-condition.c
@@ -124,7 +124,7 @@ static void test_condition_test_control_group_controller(void) {
         _cleanup_free_ char *controller_name = NULL;
         int r;
 
-        r = cg_unified_flush();
+        r = cg_unified();
         if (r < 0) {
                 log_notice_errno(r, "Skipping ConditionControlGroupController tests: %m");
                 return;