From: "Guilherme G. Piccoli" <gpicc...@canonical.com> Date: Thu, 27 Jun 2019 13:31:33 -0300
> Currently bnx2x ptp worker tries to read a register with timestamp > information in case of TX packet timestamping and in case it fails, > the routine reschedules itself indefinitely. This was reported as a > kworker always at 100% of CPU usage, which was narrowed down to be > bnx2x ptp_task. > > By following the ioctl handler, we could narrow down the problem to > an NTP tool (chrony) requesting HW timestamping from bnx2x NIC with > RX filter zeroed; this isn't reproducible for example with ptp4l > (from linuxptp) since this tool requests a supported RX filter. > It seems NIC FW timestamp mechanism cannot work well with > RX_FILTER_NONE - driver's PTP filter init routine skips a register > write to the adapter if there's not a supported filter request. > > This patch addresses the problem of bnx2x ptp thread's everlasting > reschedule by retrying the register read 10 times; between the read > attempts the thread sleeps for an increasing amount of time starting > in 1ms to give FW some time to perform the timestamping. If it still > fails after all retries, we bail out in order to prevent an unbound > resource consumption from bnx2x. > > The patch also adds an ethtool statistic for accounting the skipped > TX timestamp packets and it reduces the priority of timestamping > error messages to prevent log flooding. The code was tested using > both linuxptp and chrony. > > Reported-and-tested-by: Przemyslaw Hausman <przemyslaw.haus...@canonical.com> > Suggested-by: Sudarsana Reddy Kalluru <skall...@marvell.com> > Signed-off-by: Guilherme G. Piccoli <gpicc...@canonical.com> Applied and queued up for -stable.
