[client] usbredir: gracefully disconnect USB devices

Wait for the usbredir disconnect acknowledgement before closing SPICE.

Block replug while removal is pending and bound the shutdown wait.

client/src/main.c

@@ -224,6 +224,7 @@ static bool tickTimerFn(void * unused)
 #define FRAME_TIMING_RECORD_COUNT       1024
 #define FRAME_TIMING_PUBLISH_BATCH_SIZE 32
 #define FRAME_TIMING_PRESENT_TIMEOUT_NS 500000000ULL
+#define USB_REDIR_DISCONNECT_TIMEOUT_US 500000ULL
 
 enum FrameTimingReady
 {
@@ -1811,6 +1812,7 @@ int spiceThread(void * arg)
   };
 
   bool     connected = false;
+  PSStatus status    = PS_STATUS_SHUTDOWN;
   if (!purespice_connect(&config))
   {
     DEBUG_ERROR("Failed to connect to spice server");
@@ -1818,6 +1820,7 @@ int spiceThread(void * arg)
     goto end;
   }
   connected = true;
+  status    = PS_STATUS_RUN;
 
   int processTimeout = 100;
 #if ENABLE_USB_AUDIO
@@ -1837,7 +1840,6 @@ int spiceThread(void * arg)
       DEBUG_WARN("Failed to process USB audio redirection");
 #endif
 
-    PSStatus status;
     if ((status = purespice_process(processTimeout)) != PS_STATUS_RUN)
     {
       if (status != PS_STATUS_SHUTDOWN)
@@ -1856,8 +1858,27 @@ end:
   lgaSpice_setAvailable(false);
 #endif
 #if ENABLE_USB_AUDIO
-  if (connected && usbRedir && !lgUsbRedir_process(usbRedir))
+  if (connected && status == PS_STATUS_RUN && usbRedir)
+  {
+    if (!lgUsbRedir_process(usbRedir))
       DEBUG_WARN("Failed to disconnect USB audio device");
+    else
+    {
+      const uint64_t deadline =
+        microtime() + USB_REDIR_DISCONNECT_TIMEOUT_US;
+      while (lgUsbRedir_disconnectPending(usbRedir) &&
+          microtime() < deadline)
+      {
+        status = purespice_process(10);
+        if (status != PS_STATUS_RUN)
+          break;
+      }
+
+      if (status == PS_STATUS_RUN &&
+          lgUsbRedir_disconnectPending(usbRedir))
+        DEBUG_WARN("Timed out disconnecting USB audio device");
+    }
+  }
 #endif
   if (connected)
     purespice_disconnect();

client/src/usbredir.c

@@ -48,6 +48,7 @@ struct LG_USBRedir
   atomic_bool desiredPlugged;
   atomic_bool available;
   bool        plugged;
+  bool        disconnectPending;
 };
 
 static void setAvailable(LG_USBRedir * usbredir, bool available)
@@ -118,6 +119,12 @@ static void helloUSBRedir(void * opaque,
   setAvailable(usbredir, true);
 }
 
+static void deviceDisconnectAck(void * opaque)
+{
+  LG_USBRedir * usbredir = opaque;
+  usbredir->disconnectPending = false;
+}
+
 static void unplugDevice(LG_USBRedir * usbredir)
 {
   if (!usbredir->plugged)
@@ -131,6 +138,7 @@ static void destroyParser(LG_USBRedir * usbredir)
 {
   setAvailable(usbredir, false);
   unplugDevice(usbredir);
+  usbredir->disconnectPending = false;
 
   if (!usbredir->parser)
     return;
@@ -192,8 +200,11 @@ static bool createParser(LG_USBRedir * usbredir)
   usbredir->parser->read_func                  = readUSBRedir;
   usbredir->parser->write_func                 = writeUSBRedir;
   usbredir->parser->hello_func                 = helloUSBRedir;
+  usbredir->parser->device_disconnect_ack_func = deviceDisconnectAck;
 
   uint32_t caps[USB_REDIR_CAPS_SIZE] = { 0 };
+  usbredirparser_caps_set_cap(caps,
+      usb_redir_cap_device_disconnect_ack);
   usbredirparser_caps_set_cap(caps,
       usb_redir_cap_connect_device_version);
   usbredirparser_caps_set_cap(caps,
@@ -252,12 +263,20 @@ bool lgUsbRedir_available(const LG_USBRedir * usbredir)
   return atomic_load_explicit(&usbredir->available, memory_order_acquire);
 }
 
+bool lgUsbRedir_disconnectPending(const LG_USBRedir * usbredir)
+{
+  return usbredir->disconnectPending;
+}
+
 bool lgUsbRedir_process(LG_USBRedir * usbredir)
 {
   if (!usbredir->parser ||
       !atomic_load_explicit(&usbredir->available, memory_order_acquire))
     return flushUSBRedir(usbredir);
 
+  if (usbredir->disconnectPending)
+    return flushUSBRedir(usbredir);
+
   const bool desired = atomic_load_explicit(&usbredir->desiredPlugged,
       memory_order_acquire);
   if (desired != usbredir->plugged)
@@ -271,6 +290,8 @@ bool lgUsbRedir_process(LG_USBRedir * usbredir)
     else
     {
       unplugDevice(usbredir);
+      usbredir->disconnectPending = usbredirparser_peer_has_cap(
+          usbredir->parser, usb_redir_cap_device_disconnect_ack);
       usbredirparser_send_device_disconnect(usbredir->parser);
     }
   }

client/src/usbredir.h

@@ -57,6 +57,9 @@ void lgUsbRedir_destroy(LG_USBRedir * usbredir);
  * lgUsbRedir_process on the PureSpice processing thread. */
 void lgUsbRedir_setPlugged(LG_USBRedir * usbredir, bool plugged);
 bool lgUsbRedir_available(const LG_USBRedir * usbredir);
+/* True after a device disconnect has been sent and until the guest has
+ * completed the detach. This must be queried on the processing thread. */
+bool lgUsbRedir_disconnectPending(const LG_USBRedir * usbredir);
 
 /* Apply pending device state and flush parser output. This must be called on
  * the PureSpice processing thread. */