commit c0ce178640144c5e2149e71b456a117ece855aac
author Android Culprit Assistant <boq-android-culprit-assistant@system.gserviceaccount.com> Fri Dec 08 01:48:25 2023 +0000
committer Gerrit Code Review <noreply-gerritcodereview@google.com> Fri Dec 08 01:48:30 2023 +0000
tree a9106b19c38587656ca2f92361cf0ed35d8d2405
parent 38b8bb1e4a245de240f0761975e1d156030501fb

Revert "libprocessgroup: Use cgroup.kill"

This revert was created by Android Culprit Assistant. The culprit was identified in the following culprit search session (http://go/aca-get/91da3c52-9b76-498b-bdbd-a9de7d7ff53b).

Change-Id: I459265b9c9117d6006c1223947a202505d24c08f

libprocessgroup/processgroup.cpp

diff --git a/libprocessgroup/processgroup.cpp b/libprocessgroup/processgroup.cpp
index 4b49d09..7e27d75 100644
--- a/libprocessgroup/processgroup.cpp
+++ b/libprocessgroup/processgroup.cpp
@@ -56,7 +56,6 @@
 using namespace std::chrono_literals;
 
 #define PROCESSGROUP_CGROUP_PROCS_FILE "cgroup.procs"
-#define PROCESSGROUP_CGROUP_KILL_FILE "cgroup.kill"
 #define PROCESSGROUP_CGROUP_EVENTS_FILE "cgroup.events"
 
 bool CgroupsAvailable() {
@@ -78,29 +77,6 @@
     return true;
 }
 
-static std::string ConvertUidToPath(const char* cgroup, uid_t uid) {
-    return StringPrintf("%s/uid_%u", cgroup, uid);
-}
-
-static std::string ConvertUidPidToPath(const char* cgroup, uid_t uid, int pid) {
-    return StringPrintf("%s/uid_%u/pid_%d", cgroup, uid, pid);
-}
-
-static bool CgroupKillAvailable() {
-    static std::once_flag f;
-    static bool cgroup_kill_available = false;
-    std::call_once(f, []() {
-        std::string cg_kill;
-        CgroupGetControllerPath(CGROUPV2_HIERARCHY_NAME, &cg_kill);
-        // cgroup.kill is not on the root cgroup, so check a non-root cgroup that should always
-        // exist
-        cg_kill = ConvertUidToPath(cg_kill.c_str(), AID_ROOT) + '/' + PROCESSGROUP_CGROUP_KILL_FILE;
-        cgroup_kill_available = access(cg_kill.c_str(), F_OK) == 0;
-    });
-
-    return cgroup_kill_available;
-}
-
 static bool CgroupGetMemcgAppsPath(std::string* path) {
     CgroupController controller = CgroupMap::GetInstance().FindController("memory");
 
@@ -232,6 +208,14 @@
                                                        false);
 }
 
+static std::string ConvertUidToPath(const char* cgroup, uid_t uid) {
+    return StringPrintf("%s/uid_%u", cgroup, uid);
+}
+
+static std::string ConvertUidPidToPath(const char* cgroup, uid_t uid, int pid) {
+    return StringPrintf("%s/uid_%u/pid_%d", cgroup, uid, pid);
+}
+
 static int RemoveCgroup(const char* cgroup, uid_t uid, int pid) {
     auto path = ConvertUidPidToPath(cgroup, uid, pid);
     int ret = TEMP_FAILURE_RETRY(rmdir(path.c_str()));
@@ -378,20 +362,6 @@
         CgroupGetControllerPath(CGROUPV2_HIERARCHY_NAME, &hierarchy_root_path);
         cgroup_v2_path = ConvertUidPidToPath(hierarchy_root_path.c_str(), uid, initialPid);
 
-        if (signal == SIGKILL && CgroupKillAvailable()) {
-            LOG(VERBOSE) << "Using " << PROCESSGROUP_CGROUP_KILL_FILE << " to SIGKILL "
-                         << cgroup_v2_path;
-            const std::string killfilepath = cgroup_v2_path + '/' + PROCESSGROUP_CGROUP_KILL_FILE;
-            if (WriteStringToFile("1", killfilepath)) {
-                return true;
-            } else {
-                PLOG(ERROR) << "Failed to write 1 to " << killfilepath;
-                // Fallback to cgroup.procs below
-            }
-        }
-
-        // Since cgroup.kill only sends SIGKILLs, we read cgroup.procs to find each process to
-        // signal individually. This is more costly than using cgroup.kill for SIGKILLs.
         LOG(VERBOSE) << "Using " << PROCESSGROUP_CGROUP_PROCS_FILE << " to signal (" << signal
                      << ") " << cgroup_v2_path;