From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: followup: what's responsible for setting netdev->operstate to IF_OPER_DOWN? Date: Sun, 26 Aug 2018 13:50:06 -0700 Message-ID: <20180826135006.157d1bc2@xeon-e3> References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Linux kernel netdev mailing list To: "Robert P. J. Day" Return-path: Received: from mail-pf1-f196.google.com ([209.85.210.196]:34372 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726714AbeH0Adt (ORCPT ); Sun, 26 Aug 2018 20:33:49 -0400 Received: by mail-pf1-f196.google.com with SMTP id k19-v6so6755088pfi.1 for ; Sun, 26 Aug 2018 13:50:09 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Sun, 26 Aug 2018 11:14:33 -0400 (EDT) "Robert P. J. Day" 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