From 858f3e53430207daea8eb3ccf6b3b9df40eaa5b6 Mon Sep 17 00:00:00 2001
From: Wei Wang <wvw@google.com>
Date: Thu, 21 Feb 2019 11:25:16 -0800
Subject: [PATCH] Reduce log spam from libprocessgroup

EBUSY is expected when removing process group path if process is still
active. ESRCH is expected when kill if process died already. ENOENT is
also expected when opening cgroup path if process died already.
This CL also skip removing parent path if child failed when remove
process group.

Bug: 125340804
Test: Build and boot
Change-Id: Ief3b9cb913035a4050f6cf79c8b1e2f098e18244
---
 libprocessgroup/processgroup.cpp | 28 ++++++++++++++++++++++------
 1 file changed, 22 insertions(+), 6 deletions(-)

diff --git a/libprocessgroup/processgroup.cpp b/libprocessgroup/processgroup.cpp
index e9dec1261..c6710d088 100644
--- a/libprocessgroup/processgroup.cpp
+++ b/libprocessgroup/processgroup.cpp
@@ -170,8 +170,9 @@ static int RemoveProcessGroup(const char* cgroup, uid_t uid, int pid) {
     return ret;
 }
 
-static void RemoveUidProcessGroups(const std::string& uid_path) {
+static bool RemoveUidProcessGroups(const std::string& uid_path) {
     std::unique_ptr<DIR, decltype(&closedir)> uid(opendir(uid_path.c_str()), closedir);
+    bool empty = true;
     if (uid != NULL) {
         dirent* dir;
         while ((dir = readdir(uid.get())) != nullptr) {
@@ -185,9 +186,15 @@ static void RemoveUidProcessGroups(const std::string& uid_path) {
 
             auto path = StringPrintf("%s/%s", uid_path.c_str(), dir->d_name);
             LOG(VERBOSE) << "Removing " << path;
-            if (rmdir(path.c_str()) == -1) PLOG(WARNING) << "Failed to remove " << path;
+            if (rmdir(path.c_str()) == -1) {
+                if (errno != EBUSY) {
+                    PLOG(WARNING) << "Failed to remove " << path;
+                }
+                empty = false;
+            }
         }
     }
+    return empty;
 }
 
 void removeAllProcessGroups() {
@@ -219,9 +226,14 @@ void removeAllProcessGroups() {
                 }
 
                 auto path = StringPrintf("%s/%s", cgroup_root_path.c_str(), dir->d_name);
-                RemoveUidProcessGroups(path);
+                if (!RemoveUidProcessGroups(path)) {
+                    LOG(VERBOSE) << "Skip removing " << path;
+                    continue;
+                }
                 LOG(VERBOSE) << "Removing " << path;
-                if (rmdir(path.c_str()) == -1) PLOG(WARNING) << "Failed to remove " << path;
+                if (rmdir(path.c_str()) == -1 && errno != EBUSY) {
+                    PLOG(WARNING) << "Failed to remove " << path;
+                }
             }
         }
     }
@@ -249,6 +261,10 @@ static int DoKillProcessGroupOnce(const char* cgroup, uid_t uid, int initialPid,
     auto path = ConvertUidPidToPath(cgroup, uid, initialPid) + PROCESSGROUP_CGROUP_PROCS_FILE;
     std::unique_ptr<FILE, decltype(&fclose)> fd(fopen(path.c_str(), "re"), fclose);
     if (!fd) {
+        if (errno == ENOENT) {
+            // This happens when process is already dead
+            return 0;
+        }
         PLOG(WARNING) << "Failed to open process cgroup uid " << uid << " pid " << initialPid;
         return -1;
     }
@@ -293,7 +309,7 @@ static int DoKillProcessGroupOnce(const char* cgroup, uid_t uid, int initialPid,
         LOG(VERBOSE) << "Killing process group " << -pgid << " in uid " << uid
                      << " as part of process cgroup " << initialPid;
 
-        if (kill(-pgid, signal) == -1) {
+        if (kill(-pgid, signal) == -1 && errno != ESRCH) {
             PLOG(WARNING) << "kill(" << -pgid << ", " << signal << ") failed";
         }
     }
@@ -303,7 +319,7 @@ static int DoKillProcessGroupOnce(const char* cgroup, uid_t uid, int initialPid,
         LOG(VERBOSE) << "Killing pid " << pid << " in uid " << uid << " as part of process cgroup "
                      << initialPid;
 
-        if (kill(pid, signal) == -1) {
+        if (kill(pid, signal) == -1 && errno != ESRCH) {
             PLOG(WARNING) << "kill(" << pid << ", " << signal << ") failed";
         }
     }