vendor: bump runc to v1.2.1

For one thing, this release decouples device management from
libcontainer/cgroups. You can see the result of this in a dropped
cilium/ebpf dependency (which is only needed for device management).

NOTE that due to an issue with go mod / go list,
github.com/opencontainers/runc had to be added to
hack/unwanted-dependencies.json under x/exp. This is bogus because
opencontainers/runc does not use x/exp directly, only via cilium/ebpf
dependency (which is not vendored here).

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

vendor/github.com/opencontainers/runc/libcontainer/cgroups/utils.go

@@ -12,7 +12,7 @@ import (
 	"sync"
 	"time"
 
-	"github.com/opencontainers/runc/libcontainer/userns"
+	"github.com/moby/sys/userns"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/sys/unix"
 )
@@ -36,13 +36,13 @@ func IsCgroup2UnifiedMode() bool {
 		var st unix.Statfs_t
 		err := unix.Statfs(unifiedMountpoint, &st)
 		if err != nil {
+			level := logrus.WarnLevel
 			if os.IsNotExist(err) && userns.RunningInUserNS() {
-				// ignore the "not found" error if running in userns
-				logrus.WithError(err).Debugf("%s missing, assuming cgroup v1", unifiedMountpoint)
-				isUnified = false
-				return
+				// For rootless containers, sweep it under the rug.
+				level = logrus.DebugLevel
 			}
-			panic(fmt.Sprintf("cannot statfs cgroup root: %s", err))
+			logrus.StandardLogger().Logf(level,
+				"statfs %s: %v; assuming cgroup v1", unifiedMountpoint, err)
 		}
 		isUnified = st.Type == unix.CGROUP2_SUPER_MAGIC
 	})
@@ -136,18 +136,18 @@ func GetAllSubsystems() ([]string, error) {
 	return subsystems, nil
 }
 
-func readProcsFile(dir string) ([]int, error) {
-	f, err := OpenFile(dir, CgroupProcesses, os.O_RDONLY)
+func readProcsFile(dir string) (out []int, _ error) {
+	file := CgroupProcesses
+	retry := true
+
+again:
+	f, err := OpenFile(dir, file, os.O_RDONLY)
 	if err != nil {
 		return nil, err
 	}
 	defer f.Close()
 
-	var (
-		s   = bufio.NewScanner(f)
-		out = []int{}
-	)
-
+	s := bufio.NewScanner(f)
 	for s.Scan() {
 		if t := s.Text(); t != "" {
 			pid, err := strconv.Atoi(t)
@@ -157,6 +157,13 @@ func readProcsFile(dir string) ([]int, error) {
 			out = append(out, pid)
 		}
 	}
+	if errors.Is(s.Err(), unix.ENOTSUP) && retry {
+		// For a threaded cgroup, read returns ENOTSUP, and we should
+		// read from cgroup.threads instead.
+		file = "cgroup.threads"
+		retry = false
+		goto again
+	}
 	return out, s.Err()
 }
 
@@ -217,21 +224,26 @@ func PathExists(path string) bool {
 	return true
 }
 
-func EnterPid(cgroupPaths map[string]string, pid int) error {
-	for _, path := range cgroupPaths {
-		if PathExists(path) {
-			if err := WriteCgroupProc(path, pid); err != nil {
-				return err
-			}
-		}
-	}
-	return nil
-}
+// rmdir tries to remove a directory, optionally retrying on EBUSY.
+func rmdir(path string, retry bool) error {
+	delay := time.Millisecond
+	tries := 10
 
-func rmdir(path string) error {
+again:
 	err := unix.Rmdir(path)
-	if err == nil || err == unix.ENOENT { //nolint:errorlint // unix errors are bare
+	switch err { // nolint:errorlint // unix errors are bare
+	case nil, unix.ENOENT:
 		return nil
+	case unix.EINTR:
+		goto again
+	case unix.EBUSY:
+		if retry && tries > 0 {
+			time.Sleep(delay)
+			delay *= 2
+			tries--
+			goto again
+
+		}
 	}
 	return &os.PathError{Op: "rmdir", Path: path, Err: err}
 }
@@ -239,68 +251,40 @@ func rmdir(path string) error {
 // RemovePath aims to remove cgroup path. It does so recursively,
 // by removing any subdirectories (sub-cgroups) first.
 func RemovePath(path string) error {
-	// try the fast path first
-	if err := rmdir(path); err == nil {
+	// Try the fast path first.
+	if err := rmdir(path, false); err == nil {
 		return nil
 	}
 
 	infos, err := os.ReadDir(path)
-	if err != nil {
-		if os.IsNotExist(err) {
-			err = nil
-		}
+	if err != nil && !os.IsNotExist(err) {
 		return err
 	}
 	for _, info := range infos {
 		if info.IsDir() {
-			// We should remove subcgroups dir first
+			// We should remove subcgroup first.
 			if err = RemovePath(filepath.Join(path, info.Name())); err != nil {
 				break
 			}
 		}
 	}
 	if err == nil {
-		err = rmdir(path)
+		err = rmdir(path, true)
 	}
 	return err
 }
 
 // RemovePaths iterates over the provided paths removing them.
-// We trying to remove all paths five times with increasing delay between tries.
-// If after all there are not removed cgroups - appropriate error will be
-// returned.
 func RemovePaths(paths map[string]string) (err error) {
-	const retries = 5
-	delay := 10 * time.Millisecond
-	for i := 0; i < retries; i++ {
-		if i != 0 {
-			time.Sleep(delay)
-			delay *= 2
-		}
-		for s, p := range paths {
-			if err := RemovePath(p); err != nil {
-				// do not log intermediate iterations
-				switch i {
-				case 0:
-					logrus.WithError(err).Warnf("Failed to remove cgroup (will retry)")
-				case retries - 1:
-					logrus.WithError(err).Error("Failed to remove cgroup")
-				}
-			}
-			_, err := os.Stat(p)
-			// We need this strange way of checking cgroups existence because
-			// RemoveAll almost always returns error, even on already removed
-			// cgroups
-			if os.IsNotExist(err) {
-				delete(paths, s)
-			}
-		}
-		if len(paths) == 0 {
-			//nolint:ineffassign,staticcheck // done to help garbage collecting: opencontainers/runc#2506
-			paths = make(map[string]string)
-			return nil
+	for s, p := range paths {
+		if err := RemovePath(p); err == nil {
+			delete(paths, s)
 		}
 	}
+	if len(paths) == 0 {
+		clear(paths)
+		return nil
+	}
 	return fmt.Errorf("Failed to remove paths: %v", paths)
 }
 
@@ -431,26 +415,29 @@ func ConvertCPUSharesToCgroupV2Value(cpuShares uint64) uint64 {
 
 // ConvertMemorySwapToCgroupV2Value converts MemorySwap value from OCI spec
 // for use by cgroup v2 drivers. A conversion is needed since Resources.MemorySwap
-// is defined as memory+swap combined, while in cgroup v2 swap is a separate value.
+// is defined as memory+swap combined, while in cgroup v2 swap is a separate value,
+// so we need to subtract memory from it where it makes sense.
 func ConvertMemorySwapToCgroupV2Value(memorySwap, memory int64) (int64, error) {
-	// for compatibility with cgroup1 controller, set swap to unlimited in
-	// case the memory is set to unlimited, and swap is not explicitly set,
-	// treating the request as "set both memory and swap to unlimited".
-	if memory == -1 && memorySwap == 0 {
+	switch {
+	case memory == -1 && memorySwap == 0:
+		// For compatibility with cgroup1 controller, set swap to unlimited in
+		// case the memory is set to unlimited and the swap is not explicitly set,
+		// treating the request as "set both memory and swap to unlimited".
 		return -1, nil
-	}
-	if memorySwap == -1 || memorySwap == 0 {
-		// -1 is "max", 0 is "unset", so treat as is
+	case memorySwap == -1, memorySwap == 0:
+		// Treat -1 ("max") and 0 ("unset") swap as is.
 		return memorySwap, nil
-	}
-	// sanity checks
-	if memory == 0 || memory == -1 {
+	case memory == -1:
+		// Unlimited memory, so treat swap as is.
+		return memorySwap, nil
+	case memory == 0:
+		// Unset or unknown memory, can't calculate swap.
 		return 0, errors.New("unable to set swap limit without memory limit")
-	}
-	if memory < 0 {
+	case memory < 0:
+		// Does not make sense to subtract a negative value.
 		return 0, fmt.Errorf("invalid memory value: %d", memory)
-	}
-	if memorySwap < memory {
+	case memorySwap < memory:
+		// Sanity check.
 		return 0, errors.New("memory+swap limit should be >= memory limit")
 	}