Revert "use state machine management for exec.Pid()"

This reverts commit bbc2a995f9.

Signed-off-by: Lantao Liu <lantaol@google.com>

runtime/v1/linux/proc/deleted_state.go

@@ -69,7 +69,3 @@ func (s *deletedState) SetExited(status int) {
 func (s *deletedState) Exec(ctx context.Context, path string, r *ExecConfig) (proc.Process, error) {
 	return nil, errors.Errorf("cannot exec in a deleted state")
 }
-
-func (s *deletedState) Pid() int {
-	return -1
-}

runtime/v1/linux/proc/exec.go

@@ -69,10 +69,8 @@ func (e *execProcess) ID() string {
 }
 
 func (e *execProcess) Pid() int {
-	return e.execState.Pid()
+	e.mu.Lock()
-}
+	defer e.mu.Unlock()
-
-func (e *execProcess) pidv() int {
 	return e.pid
 }
 

runtime/v1/linux/proc/exec_state.go

@@ -31,7 +31,6 @@ type execState interface {
 	Delete(context.Context) error
 	Kill(context.Context, uint32, bool) error
 	SetExited(int)
-	Pid() int
 }
 
 type execCreatedState struct {
@@ -83,12 +82,6 @@ func (s *execCreatedState) SetExited(status int) {
 	}
 }
 
-func (s *execCreatedState) Pid() int {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
-	return s.p.pidv()
-}
-
 type execRunningState struct {
 	p *execProcess
 }
@@ -127,12 +120,6 @@ func (s *execRunningState) SetExited(status int) {
 	}
 }
 
-func (s *execRunningState) Pid() int {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
-	return s.p.pidv()
-}
-
 type execStoppedState struct {
 	p *execProcess
 }
@@ -170,7 +157,3 @@ func (s *execStoppedState) Kill(ctx context.Context, sig uint32, all bool) error
 func (s *execStoppedState) SetExited(status int) {
 	// no op
 }
-
-func (s *execStoppedState) Pid() int {
-	return s.p.pidv()
-}