Hi, I'm implementing the CAN statistics in Nuttx but I have some doubts about where to increase the drop counter. The data that is not accepted by the application is handled in the `can_datahandler` function. As the function documentation says, this function may be called either from the data receive logic if it cannot buffer the data, or from the CAN event logic if there is no listener in place ready to receive the data. I see it being called from two places, from the execution path can_input->can_in->can_callback->can_data_event->can_datahandler (in `can_data_event` there is a comment saying that the drop counter has to be increased there if can_datahanlder fails to store the frame) and from can_recvfrom_eventhandler->can_newdata->can_datahandler. Should I increase the drop counter in both cases? whenever can_datahandler is called and fails to store the data in the readahead linked list? Even when there is no listener in place?
Also, I see two different paths in can_input function: 1. If the device already has a iobuffer assigned (dev->d_iob != NULL), the first execution path previously described is executed: can_input->can_in->can_callback->can_data_event->can_datahandler (assuming that `devif_conn_event` fails to send data to the listener). As I said, if `can_datahandler` fails to store the frame in the readahead linked list, the drop counter is increased. 2. If the device doesn't have a iobuffer assigned (dev->d_iob == NULL), `can_input` calls `netdev_input` to try to get an iobuffer from the free buffers list (g_iob_freelist). If it succeeds and gets a buffer from the list, it calls `can_in` and the same path as in case 1 is taken but, if there are no more io buffers available in the list, `netdev_input` fails. I think I should also increase the drop counter in this case. Am I right? Thanks Javier Casas Marín Geotab Senior Embedded Systems Developer Direct Toll-free Visit +34 900 535 371 www.geotab.com/es Twitter <https://twitter.com/geotab> | Facebook <https://www.facebook.com/Geotab> | YouTube <https://www.youtube.com/user/MyGeotab> | LinkedIn <https://www.linkedin.com/company/geotab/>
