Fix process locking and state management

There were races with the way process states.  This displayed in ways,
especially around pausing the container for atomic operations.  Users
would get errors like, cannnot delete container in paused state and
such.

This can be eaisly reproduced with `docker` and the following command:

```bash
> (for i in `seq 1 25`; do id=$(docker create  alpine usleep 50000);docker start $id;docker commit $id;docker wait $id;docker rm $id; done)
```

This two issues that this fixes are:

* locks must be held by the owning process, not the state operations.
* If a container ends up being paused but before the operation
completes, the process exists, make sure we resume the container before
setting the the process as exited.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

runtime/v1/linux/proc/exec_state.go

@@ -25,6 +25,14 @@ import (
 	"github.com/pkg/errors"
 )
 
+type execState interface {
+	Resize(console.WinSize) error
+	Start(context.Context) error
+	Delete(context.Context) error
+	Kill(context.Context, uint32, bool) error
+	SetExited(int)
+}
+
 type execCreatedState struct {
 	p *execProcess
 }
@@ -32,11 +40,11 @@ type execCreatedState struct {
 func (s *execCreatedState) transition(name string) error {
 	switch name {
 	case "running":
-		s.p.State = &execRunningState{p: s.p}
+		s.p.execState = &execRunningState{p: s.p}
 	case "stopped":
-		s.p.State = &execStoppedState{p: s.p}
+		s.p.execState = &execStoppedState{p: s.p}
 	case "deleted":
-		s.p.State = &deletedState{}
+		s.p.execState = &deletedState{}
 	default:
 		return errors.Errorf("invalid state transition %q to %q", stateName(s), name)
 	}
@@ -44,15 +52,10 @@ func (s *execCreatedState) transition(name string) error {
 }
 
 func (s *execCreatedState) Resize(ws console.WinSize) error {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
-
 	return s.p.resize(ws)
 }
 
 func (s *execCreatedState) Start(ctx context.Context) error {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
 	if err := s.p.start(ctx); err != nil {
 		return err
 	}
@@ -63,22 +66,15 @@ func (s *execCreatedState) Delete(ctx context.Context) error {
 	if err := s.p.delete(ctx); err != nil {
 		return err
 	}
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
+
 	return s.transition("deleted")
 }
 
 func (s *execCreatedState) Kill(ctx context.Context, sig uint32, all bool) error {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
-
 	return s.p.kill(ctx, sig, all)
 }
 
 func (s *execCreatedState) SetExited(status int) {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
-
 	s.p.setExited(status)
 
 	if err := s.transition("stopped"); err != nil {
@@ -93,7 +89,7 @@ type execRunningState struct {
 func (s *execRunningState) transition(name string) error {
 	switch name {
 	case "stopped":
-		s.p.State = &execStoppedState{p: s.p}
+		s.p.execState = &execStoppedState{p: s.p}
 	default:
 		return errors.Errorf("invalid state transition %q to %q", stateName(s), name)
 	}
@@ -101,37 +97,22 @@ func (s *execRunningState) transition(name string) error {
 }
 
 func (s *execRunningState) Resize(ws console.WinSize) error {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
-
 	return s.p.resize(ws)
 }
 
 func (s *execRunningState) Start(ctx context.Context) error {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
-
 	return errors.Errorf("cannot start a running process")
 }
 
 func (s *execRunningState) Delete(ctx context.Context) error {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
-
 	return errors.Errorf("cannot delete a running process")
 }
 
 func (s *execRunningState) Kill(ctx context.Context, sig uint32, all bool) error {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
-
 	return s.p.kill(ctx, sig, all)
 }
 
 func (s *execRunningState) SetExited(status int) {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
-
 	s.p.setExited(status)
 
 	if err := s.transition("stopped"); err != nil {
@@ -146,7 +127,7 @@ type execStoppedState struct {
 func (s *execStoppedState) transition(name string) error {
 	switch name {
 	case "deleted":
-		s.p.State = &deletedState{}
+		s.p.execState = &deletedState{}
 	default:
 		return errors.Errorf("invalid state transition %q to %q", stateName(s), name)
 	}
@@ -154,16 +135,10 @@ func (s *execStoppedState) transition(name string) error {
 }
 
 func (s *execStoppedState) Resize(ws console.WinSize) error {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
-
 	return errors.Errorf("cannot resize a stopped container")
 }
 
 func (s *execStoppedState) Start(ctx context.Context) error {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
-
 	return errors.Errorf("cannot start a stopped process")
 }
 
@@ -171,15 +146,11 @@ func (s *execStoppedState) Delete(ctx context.Context) error {
 	if err := s.p.delete(ctx); err != nil {
 		return err
 	}
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
+
 	return s.transition("deleted")
 }
 
 func (s *execStoppedState) Kill(ctx context.Context, sig uint32, all bool) error {
-	s.p.mu.Lock()
-	defer s.p.mu.Unlock()
-
 	return s.p.kill(ctx, sig, all)
 }