egis_etu905: Decouple SSM and command data from device

While most of commands should run separated, others such as cancellation
can run concurrently so we cannot share command data in the device
structure, but it has to be rather per command.

Move it there

libfprint/drivers/egismoc/egis_etu905.c

@@ -31,8 +31,6 @@ struct _FpiDeviceEgisEtu905
 {
   FpDevice   parent;
   FpiSsm    *task_ssm;
-  FpiSsm         *cmd_ssm;
-  FpiUsbTransfer *cmd_transfer;
   GPtrArray *enrolled_ids;
   gint       max_enroll_stages;
 };
@@ -53,6 +51,7 @@ typedef void (*SynCmdMsgCallback) (FpDevice *device,
 typedef struct egis_etu905_command_data
 {
   SynCmdMsgCallback callback;
+  FpiUsbTransfer   *cmd_transfer;
   guchar           *buffer_in;
   gsize             length_in;
 } CommandData;
@@ -60,6 +59,7 @@ typedef struct egis_etu905_command_data
 static void
 egis_etu905_command_data_free (CommandData *data)
 {
+  g_clear_pointer (&data->cmd_transfer, fpi_usb_transfer_unref);
   g_free (data->buffer_in);
   g_free (data);
 }
@@ -248,15 +248,16 @@ egis_etu905_cmd_run_state (FpiSsm   *ssm,
                            FpDevice *device)
 {
   g_autoptr(FpiUsbTransfer) transfer = NULL;
-  FpiDeviceEgisEtu905 *self = FPI_DEVICE_EGIS_ETU905 (device);
+  CommandData *data = fpi_ssm_get_data (ssm);
 
   switch (fpi_ssm_get_cur_state (ssm))
     {
     case CMD_SEND:
-      if (self->cmd_transfer)
+      if (data->cmd_transfer)
         {
-          self->cmd_transfer->ssm = ssm;
+          transfer = g_steal_pointer (&data->cmd_transfer);
-          fpi_usb_transfer_submit (g_steal_pointer (&self->cmd_transfer),
+          transfer->ssm = ssm;
+          fpi_usb_transfer_submit (g_steal_pointer (&transfer),
                                    EGIS_ETU905_USB_SEND_TIMEOUT,
                                    fpi_device_get_cancellable (device),
                                    fpi_ssm_usb_transfer_cb,
@@ -291,15 +292,8 @@ egis_etu905_cmd_ssm_done (FpiSsm   *ssm,
                           GError   *error)
 {
   g_autoptr(GError) local_error = error;
-  FpiDeviceEgisEtu905 *self = FPI_DEVICE_EGIS_ETU905 (device);
   CommandData *data = fpi_ssm_get_data (ssm);
 
-  g_assert (self->cmd_ssm == ssm);
-  g_assert (!self->cmd_transfer || self->cmd_transfer->ssm == ssm);
-
-  self->cmd_ssm = NULL;
-  self->cmd_transfer = NULL;
-
   if (data && data->callback)
     {
       data->callback (device,
@@ -338,8 +332,8 @@ egis_etu905_exec_cmd (FpDevice         *device,
 {
   g_auto(FpiByteWriter) writer = {0};
   g_autoptr(FpiUsbTransfer) transfer = NULL;
-  FpiDeviceEgisEtu905 *self = FPI_DEVICE_EGIS_ETU905 (device);
   g_autofree CommandData *data = NULL;
+  FpiSsm *ssm = NULL;
   gsize buffer_out_length = 0;
   gboolean written = TRUE;
   guint16 check_value;
@@ -382,27 +376,17 @@ egis_etu905_exec_cmd (FpDevice         *device,
   if (cmd_destroy)
     g_clear_pointer (&cmd, cmd_destroy);
 
-  g_assert (self->cmd_ssm == NULL);
+  /* The command runs on its own dedicated SSM, carrying all its state (the
-  self->cmd_ssm = fpi_ssm_new (device,
+   * outgoing transfer and the response buffer) via the SSM data. Nothing is
-                               egis_etu905_cmd_run_state,
+   * shared on the device instance, so commands issued from different contexts
-                               CMD_STATES);
+   * (e.g. an in-progress operation and a cancellation) cannot collide. */
-
   data = g_new0 (CommandData, 1);
   data->callback = callback;
-  fpi_ssm_set_data (self->cmd_ssm, g_steal_pointer (&data),
-                    (GDestroyNotify) egis_etu905_command_data_free);
 
-  if (!written)
+  if (written)
     {
-      fpi_ssm_start (self->cmd_ssm, egis_etu905_cmd_ssm_done);
-      fpi_ssm_mark_failed (self->cmd_ssm,
-                           fpi_device_error_new (FP_DEVICE_ERROR_PROTO));
-      return;
-    }
-
       transfer = fpi_usb_transfer_new (device);
       fpi_usb_transfer_set_short_error (transfer, TRUE);
-  transfer->ssm = self->cmd_ssm;
 
       fpi_usb_transfer_fill_bulk_full (transfer,
                                        EGIS_ETU905_EP_CMD_OUT,
@@ -410,9 +394,17 @@ egis_etu905_exec_cmd (FpDevice         *device,
                                        buffer_out_length,
                                        g_free);
 
-  g_assert (self->cmd_transfer == NULL);
+      data->cmd_transfer = g_steal_pointer (&transfer);
-  self->cmd_transfer = g_steal_pointer (&transfer);
+    }
-  fpi_ssm_start (self->cmd_ssm, egis_etu905_cmd_ssm_done);
+
+  ssm = fpi_ssm_new (device, egis_etu905_cmd_run_state, CMD_STATES);
+  fpi_ssm_set_data (ssm, g_steal_pointer (&data),
+                    (GDestroyNotify) egis_etu905_command_data_free);
+
+  fpi_ssm_start (ssm, egis_etu905_cmd_ssm_done);
+
+  if (!written)
+    fpi_ssm_mark_failed (ssm, fpi_device_error_new (FP_DEVICE_ERROR_PROTO));
 }
 
 static void