runtime: Properly handle ESRCH error when signaling container

Currently kata shim v2 doesn't translate ESRCH signal, causing container
fail to stop and shim leak.

Fixes: #3874

Signed-off-by: Feng Wang <feng.wang@databricks.com>

src/runtime/virtcontainers/container.go

@@ -12,6 +12,7 @@ import (
 	"os"
 	"path/filepath"
 	"strconv"
+	"strings"
 	"syscall"
 	"time"
 
@@ -1060,7 +1061,18 @@ func (c *Container) signalProcess(ctx context.Context, processID string, signal
 		return fmt.Errorf("Container not ready, running or paused, impossible to signal the container")
 	}
 
-	return c.sandbox.agent.signalProcess(ctx, c, processID, signal, all)
+	// kill(2) method can return ESRCH in certain cases, which is not handled by containerd cri server in container_stop.go.
+	// CRIO server also doesn't handle ESRCH. So kata runtime will swallow it here.
+	var err error
+	if err = c.sandbox.agent.signalProcess(ctx, c, processID, signal, all); err != nil &&
+		strings.Contains(err.Error(), "ESRCH: No such process") {
+		c.Logger().WithFields(logrus.Fields{
+			"container":  c.id,
+			"process-id": processID,
+		}).Warn("signal encounters ESRCH, process already finished")
+		return nil
+	}
+	return err
 }
 
 func (c *Container) winsizeProcess(ctx context.Context, processID string, height, width uint32) error {

src/runtime/virtcontainers/utils/utils.go

@@ -321,6 +321,7 @@ func WaitLocalProcess(pid int, timeoutSecs uint, initialSignal syscall.Signal, l
 	if initialSignal != syscall.Signal(0) {
 		if err = syscall.Kill(pid, initialSignal); err != nil {
 			if err == syscall.ESRCH {
+				logger.WithField("pid", pid).Warnf("kill encounters ESRCH, process already finished")
 				return nil
 			}