device: rescan pci bus before waiting for new devices

So that we make sure the device pci kobject shows up.

Signed-off-by: Peng Tao <bergwolf@gmail.com>

device.go

@@ -30,7 +30,11 @@ const (
 	driverEphemeralType = "ephemeral"
 )
 
-const rootBusPath = "/devices/pci0000:00"
+const (
+	rootBusPath      = "/devices/pci0000:00"
+	pciBusRescanFile = "/sys/bus/pci/rescan"
+	pciBusMode       = 0220
+)
 
 var (
 	sysBusPrefix     = "/sys/bus/pci/devices"
@@ -58,6 +62,10 @@ var deviceHandlerList = map[string]deviceHandler{
 	driverSCSIType: virtioSCSIDeviceHandler,
 }
 
+func rescanPciBus() error {
+	return ioutil.WriteFile(pciBusRescanFile, []byte{'1'}, pciBusMode)
+}
+
 // getDevicePCIAddress fetches the complete PCI address in sysfs, based on the PCI
 // identifier provided. This should be in the format: "bridgeAddr/deviceAddr".
 // Here, bridgeAddr is the address at which the brige is attached on the root bus,
@@ -122,6 +130,13 @@ func getPCIDeviceName(s *sandbox, pciID string) (string, error) {
 		}
 	}
 
+	// Rescan pci bus if we need to wait for a new pci device
+	if err = rescanPciBus(); err != nil {
+		fieldLogger.WithError(err).Error("Failed to scan pci bus")
+		s.Unlock()
+		return "", err
+	}
+
 	// If device is not found in the device map, hotplug event has not
 	// been received yet, create and add channel to the watchers map.
 	// The key of the watchers map is the device we are interested in.

device_test.go

@@ -443,3 +443,12 @@ func TestUpdateSpecDeviceList(t *testing.T) {
 	err = updateSpecDeviceList(device, spec)
 	assert.NoError(err)
 }
+
+func TestRescanPciBus(t *testing.T) {
+	skipUnlessRoot(t)
+
+	assert := assert.New(t)
+
+	err := rescanPciBus()
+	assert.Nil(err)
+}

grpc.go

@@ -39,12 +39,6 @@ type agentGRPC struct {
 	version string
 }
 
-// PCI scanning
-const (
-	pciBusRescanFile = "/sys/bus/pci/rescan"
-	pciBusMode       = 0220
-)
-
 // CPU and Memory hotplug
 const (
 	cpuRegexpPattern = "cpu[0-9]*"
@@ -530,7 +524,7 @@ func (a *agentGRPC) CreateContainer(ctx context.Context, req *pb.CreateContainer
 
 	// re-scan PCI bus
 	// looking for hidden devices
-	if err = ioutil.WriteFile(pciBusRescanFile, []byte("1"), pciBusMode); err != nil {
+	if err = rescanPciBus(); err != nil {
 		agentLog.WithError(err).Warn("Could not rescan PCI bus")
 	}