Hi Peter, Thanks for answering. You are right, moving the timestamp generation back up fixes the issue and it makes more sense to have the code there, before branching the code flow, than having it duplicated in both paths.
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/> On Wed, Mar 5, 2025 at 7:11 PM Peter van der Perk <peter.vanderp...@nxp.com> wrote: > Hi Javier, > > I think it's a regression from the IOB rewrite. > > The original implementation added the timestamp before calling either > devif_conn_event or can_data_event. > > https://github.com/apache/nuttx/blob/55d9e5f7af05e75ca62f57863b880d723aa83c56/net/can/can_callback.c#L123-136 > > I think moving the code up would fix it. > > Yours sincerely, > > Peter van der Perk > > -----Original Message----- > From: Javier Casas Marin <javierca...@geotab.com.INVALID> > Sent: Wednesday, March 5, 2025 2:27 PM > To: dev@nuttx.apache.org > Subject: socket CAN timestamp missing > > Hi Nuttxaddicts, > > After configuring the CAN socket with SO_TIMESTAMP, the application > reading the socket is sometimes getting an empty timestamp in some > situations. I've been debugging this issue and I this is what I found: > > There are two paths when receiving a CAN frame from the interrupt, if > there is someone waiting for a frame, the can_recvfrom_eventhandler > callback is called to deliver the frame to the application, otherwise the > frame is stored in the read-ahead list. > > When there is no listener available the timestamp is generated in the > can_callback function just before calling can_data_event to store the CAN > frame in the read-ahead list. But, if there is a listener waiting, the > can_recvfrom_eventhandler is called and the timestamp is not generated at > all, so the recvmsg call in the application side returns an empty timestamp. > > I think this is a bug. Why is the timestant not added in the explained > case? Adding it in the can_recvfrom_newdata function solves the issue. > > Javier Casas Marín > Geotab > > Senior Embedded Systems Developer > > Direct > Toll-free > > Visit > > > +34 900 535 371 > http://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/> >
