lxd/device: Add support for discovering multiple unix-hotplug devices

lxd/device/unix_hotplug.go

@@ -16,16 +16,25 @@ import (
 	"github.com/canonical/lxd/shared/validate"
 )
 
-// unixHotplugIsOurDevice indicates whether the unixHotplug device event qualifies as part of our device.
-// This function is not defined against the unixHotplug struct type so that it can be used in event
-// callbacks without needing to keep a reference to the unixHotplug device struct.
-func unixHotplugIsOurDevice(config deviceConfig.Device, unixHotplug *UnixHotplugEvent) bool {
-	// Check if event matches criteria for this device, if not return.
-	if (config["vendorid"] != "" && config["vendorid"] != unixHotplug.Vendor) || (config["productid"] != "" && config["productid"] != unixHotplug.Product) {
+// unixHotplugDeviceMatch matches a unix-hotplug device based on vendorid and productid. USB bus and devices with a major number of 0 are ignored. This function is used to indicate whether a unix hotplug event qualifies as part of our registered devices, and to load matching devices.
+func unixHotplugDeviceMatch(config deviceConfig.Device, vendorid string, productid string, subsystem string, major uint32) bool {
+	match := false
+	vendorIDMatch := vendorid == config["vendorid"]
+	productIDMatch := productid == config["productid"]
+
+	if strings.HasPrefix(subsystem, "usb") || major == 0 {
 		return false
 	}
 
-	return true
+	if config["vendorid"] != "" && config["productid"] != "" {
+		match = vendorIDMatch && productIDMatch
+	} else if config["vendorid"] != "" {
+		match = vendorIDMatch
+	} else if config["productid"] != "" {
+		match = productIDMatch
+	}
+
+	return match
 }
 
 type unixHotplug struct {
@@ -89,8 +98,7 @@ func (d *unixHotplug) validateConfig(instConf instance.ConfigReader) error {
 
 // Register is run after the device is started or when LXD starts.
 func (d *unixHotplug) Register() error {
-	// Extract variables needed to run the event hook so that the reference to this device
-	// struct is not needed to be kept in memory.
+	// Extract variables needed to run the event hook so that the reference to this device struct is not required to be stored in memory.
 	devicesPath := d.inst.DevicesPath()
 	devConfig := d.config
 	deviceName := d.name
@@ -101,7 +109,7 @@ func (d *unixHotplug) Register() error {
 		runConf := deviceConfig.RunConfig{}
 
 		if e.Action == "add" {
-			if !unixHotplugIsOurDevice(devConfig, &e) {
+			if !unixHotplugDeviceMatch(devConfig, e.Vendor, e.Product, e.Subsystem, e.Major) {
 				return nil, nil
 			}
 
@@ -149,29 +157,36 @@ func (d *unixHotplug) Start() (*deviceConfig.RunConfig, error) {
 	runConf := deviceConfig.RunConfig{}
 	runConf.PostHooks = []func() error{d.Register}
 
-	device := d.loadUnixDevice()
-	if d.isRequired() && device == nil {
+	devices := d.loadUnixDevices()
+	if d.isRequired() && devices == nil {
 		return nil, fmt.Errorf("Required Unix Hotplug device not found")
 	}
 
-	if device == nil {
+	if devices == nil {
 		return &runConf, nil
 	}
 
-	devnum := device.Devnum()
-	major := uint32(devnum.Major())
-	minor := uint32(devnum.Minor())
+	for _, device := range devices {
+		devnum := device.Devnum()
+		major := uint32(devnum.Major())
+		minor := uint32(devnum.Minor())
+
+		// Setup device.
+		var err error
+		if device.Subsystem() == "block" {
+			err = unixDeviceSetupBlockNum(d.state, d.inst.DevicesPath(), "unix", d.name, d.config, major, minor, device.Devnode(), false, &runConf)
+		} else {
+			err = unixDeviceSetupCharNum(d.state, d.inst.DevicesPath(), "unix", d.name, d.config, major, minor, device.Devnode(), false, &runConf)
+		}
 
-	// setup device
-	var err error
-	if device.Subsystem() == "block" {
-		err = unixDeviceSetupBlockNum(d.state, d.inst.DevicesPath(), "unix", d.name, d.config, major, minor, device.Devnode(), false, &runConf)
-	} else {
-		err = unixDeviceSetupCharNum(d.state, d.inst.DevicesPath(), "unix", d.name, d.config, major, minor, device.Devnode(), false, &runConf)
-	}
+		if err != nil {
+			err := unixDeviceRemove(d.inst.DevicesPath(), "unix", d.name, "", &runConf)
+			if err != nil {
+				return nil, err
+			}
 
-	if err != nil {
-		return nil, err
+			return nil, err
+		}
 	}
 
 	return &runConf, nil
@@ -203,9 +218,9 @@ func (d *unixHotplug) postStop() error {
 	return nil
 }
 
-// loadUnixDevice scans the host machine for unix devices with matching product/vendor ids
-// and returns the first matching device with the subsystem type char or block.
-func (d *unixHotplug) loadUnixDevice() *udev.Device {
+// loadUnixDevices scans the host machine for unix devices with matching product/vendor ids
+// and returns the matching devices with subsystem types of char or block.
+func (d *unixHotplug) loadUnixDevices() []*udev.Device {
 	// Find device if exists
 	u := udev.Udev{}
 	e := u.NewEnumerate()
@@ -230,27 +245,22 @@ func (d *unixHotplug) loadUnixDevice() *udev.Device {
 	}
 
 	devices, _ := e.Devices()
-	var device *udev.Device
+	var matchingDevices []*udev.Device
 	for i := range devices {
-		device = devices[i]
+		device := devices[i]
 
-		if device == nil {
+		if device == nil || device.Devnode() == "" {
 			continue
 		}
 
-		devnum := device.Devnum()
-		if devnum.Major() == 0 || devnum.Minor() == 0 {
-			continue
-		}
+		match := unixHotplugDeviceMatch(d.config, device.PropertyValue("ID_VENDOR_ID"), device.PropertyValue("ID_MODEL_ID"), device.Subsystem(), uint32(device.Devnum().Major()))
 
-		if device.Devnode() == "" {
+		if !match {
 			continue
 		}
 
-		if !strings.HasPrefix(device.Subsystem(), "usb") {
-			return device
-		}
+		matchingDevices = append(matchingDevices, device)
 	}
 
-	return nil
+	return matchingDevices
 }