liblmkd_utils: Use libprocessgroup to create cgroups am: 911f106a4a

Original change: https://android-review.googlesource.com/c/platform/system/memory/lmkd/+/2034587

Change-Id: I682dfc8e3b463bd5203d5102ec37c2af5422e64f

Android.bp

@@ -64,6 +64,7 @@ cc_library_static {
     recovery_available: true,
     shared_libs: [
         "libcutils",
+        "libprocessgroup",
     ],
     export_include_dirs: ["include"],
     cppflags: [

liblmkd_utils.cpp

@@ -22,8 +22,9 @@
 #include <stdio.h>
 #include <unistd.h>
 
-#include <liblmkd_utils.h>
 #include <cutils/sockets.h>
+#include <liblmkd_utils.h>
+#include <processgroup/processgroup.h>
 
 int lmkd_connect() {
     return socket_local_client("lmkd",
@@ -78,34 +79,6 @@ enum update_props_result lmkd_update_props(int sock) {
 }
 
 int create_memcg(uid_t uid, pid_t pid) {
-    char buf[256];
-    int tasks_file;
-    int written;
-
-    snprintf(buf, sizeof(buf), "/dev/memcg/apps/uid_%u", uid);
-    if (mkdir(buf, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH) < 0 &&
-        errno != EEXIST) {
-        return -1;
-    }
-
-    snprintf(buf, sizeof(buf), "/dev/memcg/apps/uid_%u/pid_%u", uid, pid);
-    if (mkdir(buf, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH) < 0 &&
-        errno != EEXIST) {
-        return -1;
-    }
-
-    snprintf(buf, sizeof(buf), "/dev/memcg/apps/uid_%u/pid_%u/tasks", uid, pid);
-    tasks_file = open(buf, O_WRONLY);
-    if (tasks_file < 0) {
-        return -2;
-    }
-    written = snprintf(buf, sizeof(buf), "%u", pid);
-    if (__predict_false(written >= (int)sizeof(buf))) {
-        written = sizeof(buf) - 1;
-    }
-    written = TEMP_FAILURE_RETRY(write(tasks_file, buf, written));
-    close(tasks_file);
-
-    return (written < 0) ? -3 : 0;
+    return createProcessGroup(uid, pid, true) == 0 ? 0 : -1;
 }
 

tests/Android.bp

@@ -23,6 +23,7 @@ cc_test {
         "libbase",
         "liblog",
         "libcutils",
+        "libprocessgroup",
     ],
 
     static_libs: [
@@ -53,6 +54,7 @@ cc_test {
         "libbase",
         "liblog",
         "libcutils",
+        "libprocessgroup",
     ],
 
     static_libs: [