Hi freebsd-net, We've encountered an issue with unloading the iavf(4) driver on FreeBSD 12.1 (and stable). On a VM with two iavf(4) interfaces, if we send heavy traffic to iavf1 and try to kldunload the driver, the kldunload process hangs on iavf0 until iavf1 stops receiving traffic.
After some debugging, it looks like epoch_drain_callbacks() [via if_detach_internal()] tries to switch CPUs to run on one that iavf1 is using for RX processing, but since iavf1 is busy, it can't make the switch, so cpu_switch() just hangs and nothing happens until iavf1's RX thread stops being busy. I can work around this by inserting a kern_yield(PRI_USER) somewhere in one of the iavf txrx functions that iflib calls into (e.g. iavf_isc_rxd_available), but that's not a proper fix. Does anyone know what to do to prevent this from happening? Wildly guessing, does maybe epoch_drain_callbacks() need a higher priority than the PI_SOFT used in the group taskqueues used in iflib's RX processing? - Eric _______________________________________________ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
