Merge "init: skip cgroup/task_profiles configuration if cgroups are disabled" am: 537ab23872

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2263261

Change-Id: Id77ccea3ee5823861cd2517dac694fc8d2f6452e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

init/init.cpp

@@ -662,6 +662,10 @@ static Result<void> wait_for_coldboot_done_action(const BuiltinArguments& args)
 }
 
 static Result<void> SetupCgroupsAction(const BuiltinArguments&) {
+    if (!CgroupsAvailable()) {
+        LOG(INFO) << "Cgroups support in kernel is not enabled";
+        return {};
+    }
     // Have to create <CGROUPS_RC_DIR> using make_dir function
     // for appropriate sepolicy to be set for it
     make_dir(android::base::Dirname(CGROUPS_RC_PATH), 0711);

init/service.cpp

@@ -692,24 +692,28 @@ Result<void> Service::Start() {
     start_order_ = next_start_order_++;
     process_cgroup_empty_ = false;
 
-    bool use_memcg = swappiness_ != -1 || soft_limit_in_bytes_ != -1 || limit_in_bytes_ != -1 ||
-                      limit_percent_ != -1 || !limit_property_.empty();
-    errno = -createProcessGroup(proc_attr_.uid, pid_, use_memcg);
-    if (errno != 0) {
-        if (char byte = 0; write((*pipefd)[1], &byte, 1) < 0) {
-            return ErrnoError() << "sending notification failed";
+    if (CgroupsAvailable()) {
+        bool use_memcg = swappiness_ != -1 || soft_limit_in_bytes_ != -1 || limit_in_bytes_ != -1 ||
+                         limit_percent_ != -1 || !limit_property_.empty();
+        errno = -createProcessGroup(proc_attr_.uid, pid_, use_memcg);
+        if (errno != 0) {
+            if (char byte = 0; write((*pipefd)[1], &byte, 1) < 0) {
+                return ErrnoError() << "sending notification failed";
+            }
+            return Error() << "createProcessGroup(" << proc_attr_.uid << ", " << pid_
+                           << ") failed for service '" << name_ << "'";
         }
-        return Error() << "createProcessGroup(" << proc_attr_.uid << ", " << pid_
-                       << ") failed for service '" << name_ << "'";
-    }
 
-    // When the blkio controller is mounted in the v1 hierarchy, NormalIoPriority is
-    // the default (/dev/blkio). When the blkio controller is mounted in the v2 hierarchy, the
-    // NormalIoPriority profile has to be applied explicitly.
-    SetProcessProfiles(proc_attr_.uid, pid_, {"NormalIoPriority"});
+        // When the blkio controller is mounted in the v1 hierarchy, NormalIoPriority is
+        // the default (/dev/blkio). When the blkio controller is mounted in the v2 hierarchy, the
+        // NormalIoPriority profile has to be applied explicitly.
+        SetProcessProfiles(proc_attr_.uid, pid_, {"NormalIoPriority"});
 
-    if (use_memcg) {
-        ConfigureMemcg();
+        if (use_memcg) {
+            ConfigureMemcg();
+        }
+    } else {
+        process_cgroup_empty_ = true;
     }
 
     if (oom_score_adjust_ != DEFAULT_OOM_SCORE_ADJUST) {

init/service_utils.cpp

@@ -280,6 +280,15 @@ Result<void> SetProcessAttributes(const ProcessAttributes& attr) {
 }
 
 Result<void> WritePidToFiles(std::vector<std::string>* files) {
+    if (files->empty()) {
+        // No files to write pid to, exit early.
+        return {};
+    }
+
+    if (!CgroupsAvailable()) {
+        return Error() << "cgroups are not available";
+    }
+
     // See if there were "writepid" instructions to write to files under cpuset path.
     std::string cpuset_path;
     if (CgroupGetControllerPath("cpuset", &cpuset_path)) {

libprocessgroup/include/processgroup/processgroup.h

@@ -28,6 +28,7 @@ __BEGIN_DECLS
 
 static constexpr const char* CGROUPV2_CONTROLLER_NAME = "cgroup2";
 
+bool CgroupsAvailable();
 bool CgroupGetControllerPath(const std::string& cgroup_name, std::string* path);
 bool CgroupGetControllerFromPath(const std::string& path, std::string* cgroup_name);
 bool CgroupGetAttributePath(const std::string& attr_name, std::string* path);

libprocessgroup/processgroup.cpp

@@ -55,6 +55,11 @@ using namespace std::chrono_literals;
 
 #define PROCESSGROUP_CGROUP_PROCS_FILE "/cgroup.procs"
 
+bool CgroupsAvailable() {
+    static bool cgroups_available = access("/proc/cgroups", F_OK) == 0;
+    return cgroups_available;
+}
+
 bool CgroupGetControllerPath(const std::string& cgroup_name, std::string* path) {
     auto controller = CgroupMap::GetInstance().FindController(cgroup_name);