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Merge pull request #1678 from sboeuf/sboeuf/subreaper 

libcontainer: Do not wait for signalled processes if subreaper is set
This commit is contained in:
Mrunal Patel 2017-12-15 08:47:07 -08:00 committed by GitHub
parent 7f24b40cc5 bb912eb00c
commit e6516b3d5d
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 31 additions and 3 deletions
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23
libcontainer/init_linux.go
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@ -494,6 +494,16 @@ func signalAllProcesses(m cgroups.Manager, s os.Signal) error {
logrus.Warn(err)
}
subreaper, err := system.GetSubreaper()
if err != nil {
// The error here means that PR_GET_CHILD_SUBREAPER is not
// supported because this code might run on a kernel older
// than 3.4. We don't want to throw an error in that case,
// and we simplify things, considering there is no subreaper
// set.
subreaper = 0
}
for _, p := range procs {
if s != unix.SIGKILL {
if ok, err := isWaitable(p.Pid); err != nil {
@ -507,9 +517,16 @@ func signalAllProcesses(m cgroups.Manager, s os.Signal) error {
}
}
if _, err := p.Wait(); err != nil {
if !isNoChildren(err) {
logrus.Warn("wait: ", err)
// In case a subreaper has been setup, this code must not
// wait for the process. Otherwise, we cannot be sure the
// current process will be reaped by the subreaper, while
// the subreaper might be waiting for this process in order
// to retrieve its exit code.
if subreaper == 0 {
if _, err := p.Wait(); err != nil {
if !isNoChildren(err) {
logrus.Warn("wait: ", err)
}
}
}
}

11
libcontainer/system/linux.go
View File

@ -134,3 +134,14 @@ func RunningInUserNS() bool {
func SetSubreaper(i int) error {
return unix.Prctl(PR_SET_CHILD_SUBREAPER, uintptr(i), 0, 0, 0)
}
// GetSubreaper returns the subreaper setting for the calling process
func GetSubreaper() (int, error) {
var i uintptr
if err := unix.Prctl(unix.PR_GET_CHILD_SUBREAPER, uintptr(unsafe.Pointer(&i)), 0, 0, 0); err != nil {
return -1, err
}
return int(i), nil
}