From 0ac92aab3f619d38d9162a904aec2cd704f47829 Mon Sep 17 00:00:00 2001
From: Kir Kolyshkin <kolyshkin@gmail.com>
Date: Thu, 28 May 2020 07:49:44 -0700
Subject: [PATCH 1/2] cgroups/fs2: make removeCgroupPath faster

1. In cases there are no sub-cgroups, a single rmdir should be faster
than iterating through the list of files.

2. Use unix.Rmdir() to save one more syscall since os.Remove() tries
unlink(2) first which fails on a directory, and only then tries
rmdir(2).

3. Re-use rmdir.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
---
 libcontainer/cgroups/fs2/fs2.go | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/libcontainer/cgroups/fs2/fs2.go b/libcontainer/cgroups/fs2/fs2.go
index 55668470377..69b9948a4da 100644
--- a/libcontainer/cgroups/fs2/fs2.go
+++ b/libcontainer/cgroups/fs2/fs2.go
@@ -11,6 +11,7 @@ import (
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/configs"
 	"github.com/pkg/errors"
+	"golang.org/x/sys/unix"
 )
 
 type manager struct {
@@ -156,9 +157,22 @@ func (m *manager) Freeze(state configs.FreezerState) error {
 	return nil
 }
 
+func rmdir(path string) error {
+	err := unix.Rmdir(path)
+	if err == nil || err == unix.ENOENT {
+		return nil
+	}
+	return &os.PathError{Op: "rmdir", Path: path, Err: err}
+}
+
 // removeCgroupPath aims to remove cgroup path recursively
 // Because there may be subcgroups in it.
 func removeCgroupPath(path string) error {
+	// try the fast path first
+	if err := rmdir(path); err == nil {
+		return nil
+	}
+
 	infos, err := ioutil.ReadDir(path)
 	if err != nil {
 		if os.IsNotExist(err) {
@@ -175,10 +189,7 @@ func removeCgroupPath(path string) error {
 		}
 	}
 	if err == nil {
-		err = os.Remove(path)
-		if os.IsNotExist(err) {
-			err = nil
-		}
+		err = rmdir(path)
 	}
 	return err
 }

From a78e21b5001dbe0d2cc6de630fc3e0d62b023ca5 Mon Sep 17 00:00:00 2001
From: Kir Kolyshkin <kolyshkin@gmail.com>
Date: Thu, 28 May 2020 11:45:14 -0700
Subject: [PATCH 2/2] tests/int/delete.bats: fixups

1. __runc does not set $status, so the check is misleading.

2. Add set +eux to the nest.sh script so we can error out early, and see
   what is going on.

3. Doing "echo +io" > cgroup.controllers is giving an error on my
   machine ("sh: write error: Operation not supported"). It is probably
   fine to just enable pids controller.

4. Add status check for runc exec nest.sh

5. Remove the second check for cgroup.threads contents -- it was already
   checked earlier (the output of nest.sh script).

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
---
 tests/integration/delete.bats | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/tests/integration/delete.bats b/tests/integration/delete.bats
index 44a76fc9635..9c80909dc1e 100644
--- a/tests/integration/delete.bats
+++ b/tests/integration/delete.bats
@@ -71,7 +71,6 @@ function teardown() {
 
   # create a sub process
   __runc exec -d test_busybox sleep 1d
-  [ "$status" -eq 0 ]
 
   # find the pid of sleep
   pid=$(__runc exec test_busybox ps -a | grep 1d | awk '{print $1}')
@@ -79,8 +78,9 @@ function teardown() {
 
   # create subcgroups
   cat <<EOF > nest.sh
+  set -e -u -x
   cd /sys/fs/cgroup
-  for f in \$(cat cgroup.controllers); do echo +\$f > cgroup.subtree_control; done
+  echo +pids > cgroup.subtree_control
   mkdir foo
   cd foo
   echo threaded > cgroup.type
@@ -88,15 +88,12 @@ function teardown() {
   cat cgroup.threads
 EOF
   cat nest.sh | runc exec test_busybox sh
-  [[ ${output} =~ [0-9]+ ]]
+  [ "$status" -eq 0 ]
+  [[ "$output" =~ [0-9]+ ]]
 
   # check create subcgroups success
   [ -d $CGROUP_PATH/foo ]
 
-  # check cgroup.threads' value
-  runc exec test_busybox cat /sys/fs/cgroup/foo/cgroup.threads
-  [[ ${output} =~ [0-9]+ ]]
-
   # force delete test_busybox
   runc delete --force test_busybox