libprocessgroup: fall back to cpuset in get_sched_policy

Since vendor has a way to override the group cpu/schedtune setup, we
cannot assume the group will always return valid data. This CL let
get_sched_policy to fallback to cpuset if no valid data found in
cpu/schedtune cgroup. In longer term, we should find a way to cache the
group or app's process state in framework other than relying on reading
cgroup back.

Test: /data/nativetest64/libcutils_test/libcutils_test
Bug: 210066228
Signed-off-by: Wei Wang <wvw@google.com>
Change-Id: I8b4396365a7fc2d93e3a22746195585c140eef3c

1 files changed, 30 insertions, 21 deletions

diff --git a/libprocessgroup/sched_policy.cpp b/libprocessgroup/sched_policy.cpp
index 1a4196a4d..169b1d3e0 100644
--- a/libprocessgroup/sched_policy.cpp
+++ b/libprocessgroup/sched_policy.cpp
@@ -165,27 +165,7 @@ static int getCGroupSubsys(int tid, const char* subsys, std::string& subgroup) {
     return 0;
 }
 
-int get_sched_policy(int tid, SchedPolicy* policy) {
-    if (tid == 0) {
-        tid = GetThreadId();
-    }
-
-    std::string group;
-    if (schedboost_enabled()) {
-        if ((getCGroupSubsys(tid, "schedtune", group) < 0) &&
-            (getCGroupSubsys(tid, "cpu", group) < 0)) {
-                LOG(ERROR) << "Failed to find cpu cgroup for tid " << tid;
-                return -1;
-        }
-    }
-    if (group.empty() && cpusets_enabled()) {
-        if (getCGroupSubsys(tid, "cpuset", group) < 0) {
-            LOG(ERROR) << "Failed to find cpuset cgroup for tid " << tid;
-            return -1;
-        }
-    }
-
-    // TODO: replace hardcoded directories
+static int get_sched_policy_from_group(const std::string& group, SchedPolicy* policy) {
     if (group.empty()) {
         *policy = SP_FOREGROUND;
     } else if (group == "foreground") {
@@ -205,6 +185,35 @@ int get_sched_policy(int tid, SchedPolicy* policy) {
     return 0;
 }
 
+int get_sched_policy(int tid, SchedPolicy* policy) {
+    if (tid == 0) {
+        tid = GetThreadId();
+    }
+
+    std::string group;
+    if (schedboost_enabled()) {
+        if ((getCGroupSubsys(tid, "schedtune", group) < 0) &&
+            (getCGroupSubsys(tid, "cpu", group) < 0)) {
+            LOG(ERROR) << "Failed to find cpu cgroup for tid " << tid;
+            return -1;
+        }
+        // Wipe invalid group to fallback to cpuset
+        if (!group.empty()) {
+            if (get_sched_policy_from_group(group, policy) < 0) {
+                group.clear();
+            } else {
+                return 0;
+            }
+        }
+    }
+
+    if (cpusets_enabled() && getCGroupSubsys(tid, "cpuset", group) < 0) {
+        LOG(ERROR) << "Failed to find cpuset cgroup for tid " << tid;
+        return -1;
+    }
+    return get_sched_policy_from_group(group, policy);
+}
+
 #else
 
 /* Stubs for non-Android targets. */