vm_control: clarify that USB attach only uses dev_path

The bus/address and vendor/product IDs are unused internally; only the
usbdevfs device path matters. Update the internal API parameters and
documentation to match.

The crosvm_control `crosvm_client_usb_attach()` function must keep the
extra parameters to maintain API compatibility, but its documentation is
updated to note that they are unused.

BUG=None
TEST=Attach USB device to Crostini on trogdor

Change-Id: I7086f61a420be1dbf3dd1877fa86a5e82c0c5c77
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3708640
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Dennis Kempin <denniskempin@google.com>
Commit-Queue: Daniel Verkamp <dverkamp@chromium.org>

crosvm_control/src/lib.rs

@@ -174,10 +174,10 @@ pub extern "C" fn crosvm_client_usb_list(
 /// # Arguments
 ///
 /// * `socket_path` - Path to the crosvm control socket
-/// * `bus` - USB device bus ID
-/// * `addr` - USB device address
-/// * `vid` - USB device vendor ID
-/// * `pid` - USB device product ID
+/// * `bus` - USB device bus ID (unused)
+/// * `addr` - USB device address (unused)
+/// * `vid` - USB device vendor ID (unused)
+/// * `pid` - USB device product ID (unused)
 /// * `dev_path` - Path to the USB device (Most likely `/dev/bus/usb/<bus>/<addr>`).
 /// * `out_port` - (optional) internal port will be written here if provided.
 ///
@@ -185,10 +185,10 @@ pub extern "C" fn crosvm_client_usb_list(
 #[no_mangle]
 pub extern "C" fn crosvm_client_usb_attach(
     socket_path: *const c_char,
-    bus: u8,
-    addr: u8,
-    vid: u16,
-    pid: u16,
+    _bus: u8,
+    _addr: u8,
+    _vid: u16,
+    _pid: u16,
     dev_path: *const c_char,
     out_port: *mut u8,
 ) -> bool {
@@ -199,9 +199,7 @@ pub extern "C" fn crosvm_client_usb_attach(
             }
             let dev_path = Path::new(unsafe { CStr::from_ptr(dev_path) }.to_str().unwrap_or(""));
 
-            if let Ok(UsbControlResult::Ok { port }) =
-                do_usb_attach(&socket_path, bus, addr, vid, pid, dev_path)
-            {
+            if let Ok(UsbControlResult::Ok { port }) = do_usb_attach(&socket_path, dev_path) {
                 if !out_port.is_null() {
                     unsafe { *out_port = port };
                 }

devices/src/usb/host_backend/host_backend_device_provider.rs

@@ -263,7 +263,7 @@ impl ProviderInner {
         let tube = self.control_tube.lock();
         let cmd = tube.recv().map_err(Error::ReadControlTube)?;
         let result = match cmd {
-            UsbControlCommand::AttachDevice { file, .. } => self.handle_attach_device(file),
+            UsbControlCommand::AttachDevice { file } => self.handle_attach_device(file),
             UsbControlCommand::DetachDevice { port } => self.handle_detach_device(port),
             UsbControlCommand::ListDevice { ports } => self.handle_list_devices(ports),
         };

src/main.rs

@@ -366,10 +366,9 @@ fn make_rt(cmd: cmdline::MakeRTCommand) -> std::result::Result<(), ()> {
 }
 
 fn usb_attach(cmd: cmdline::UsbAttachCommand) -> ModifyUsbResult<UsbControlResult> {
-    let (bus, addr, vid, pid) = cmd.addr;
     let dev_path = Path::new(&cmd.dev_path);
 
-    do_usb_attach(cmd.socket_path, bus, addr, vid, pid, dev_path)
+    do_usb_attach(cmd.socket_path, dev_path)
 }
 
 fn usb_detach(cmd: cmdline::UsbDetachCommand) -> ModifyUsbResult<UsbControlResult> {

vm_control/src/client.rs

@@ -46,22 +46,12 @@ pub fn vms_request<T: AsRef<Path> + std::fmt::Debug>(
 
 pub fn do_usb_attach<T: AsRef<Path> + std::fmt::Debug>(
     socket_path: T,
-    bus: u8,
-    addr: u8,
-    vid: u16,
-    pid: u16,
     dev_path: &Path,
 ) -> ModifyUsbResult<UsbControlResult> {
     let usb_file = open_file(dev_path, OpenOptions::new().read(true).write(true))
         .map_err(|e| ModifyUsbError::FailedToOpenDevice(dev_path.into(), e))?;
 
-    let request = VmRequest::UsbCommand(UsbControlCommand::AttachDevice {
-        bus,
-        addr,
-        vid,
-        pid,
-        file: usb_file,
-    });
+    let request = VmRequest::UsbCommand(UsbControlCommand::AttachDevice { file: usb_file });
     let response =
         handle_request(&request, socket_path).map_err(|_| ModifyUsbError::SocketFailed)?;
     match response {

vm_control/src/lib.rs

@@ -186,10 +186,6 @@ pub enum DiskControlResult {
 #[derive(Serialize, Deserialize, Debug)]
 pub enum UsbControlCommand {
     AttachDevice {
-        bus: u8,
-        addr: u8,
-        vid: u16,
-        pid: u16,
         #[serde(with = "with_as_descriptor")]
         file: File,
     },