On Sun, 26 Aug 2018, Stephen Hemminger wrote: > On Sun, 26 Aug 2018 11:14:33 -0400 (EDT) > "Robert P. J. Day" <rpj...@crashcourse.ca> wrote: > > > apologies for the constant pleas for assistance, but i think i'm > > zeroing in on the problem that started all this. recap: custom > > FPGA-based linux box with multiple ports, where the current symptom is > > that there is no userspace notification when someone simply unplugs > > one of the ports ("ifconfig" shows that interface still RUNNING). > > > > as i read it, an active ethernet interface should be both UP (the > > administrative state) and RUNNING (the RFC 2863-defined operational > > state). if i unplug, i've verified on a standard net port on my laptop > > that the interface is still UP, but no longer RUNNING, which makes > > perfect sense. i plug back in, interface starts RUNNING again. so > > where's the problem? > > > > i can see that whether ifconfig shows an interface RUNNING is > > defined in net/core/dev.c: > > > > unsigned int dev_get_flags(const struct net_device *dev) > > { > > unsigned int flags; > > > > flags = (dev->flags & ~(IFF_PROMISC | > > IFF_ALLMULTI | > > IFF_RUNNING | > > IFF_LOWER_UP | > > IFF_DORMANT)) | > > (dev->gflags & (IFF_PROMISC | > > IFF_ALLMULTI)); > > > > if (netif_running(dev)) { > > if (netif_oper_up(dev)) > > flags |= IFF_RUNNING; <---- THERE > > if (netif_carrier_ok(dev)) > > flags |= IFF_LOWER_UP; > > if (netif_dormant(dev)) > > flags |= IFF_DORMANT; > > } > > > > return flags; > > } > > > > where netif_oper_up() is defined as: > > > > static inline bool netif_oper_up(const struct net_device *dev) > > { > > return (dev->operstate == IF_OPER_UP || > > dev->operstate == IF_OPER_UNKNOWN /* backward compat */); > > } > > > > so i am simply assuming that the underlying problem is that, > > somewhere down below, the unplugging of a port is somehow not setting > > dev->operstate to its proper value of IF_OPER_DOWN. > > > > that would clearly explain everything, and i'm about to dig even > > further to see where the event of unplugging a port *should* be > > recognized, but does this sound like a reasonable diagnosis? there > > have been other problems with the programming of the FPGA, so it would > > surprise absolutely no one to learn that this aspect was > > misprogrammed. > > > > rday > > > > There is no reason drivers should ever muck with flags directly. > You probably are looking for netif_detach
i assume you mean netif_device_detach; i'll check into that. rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca/dokuwiki Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================