From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Robert P. J. Day" Subject: followup: what's responsible for setting netdev->operstate to IF_OPER_DOWN? Date: Sun, 26 Aug 2018 11:14:33 -0400 (EDT) Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII To: Linux kernel netdev mailing list Return-path: Received: from cpanel4.indieserve.net ([199.212.143.9]:53264 "EHLO cpanel4.indieserve.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726779AbeHZS7v (ORCPT ); Sun, 26 Aug 2018 14:59:51 -0400 Received: from cpef81d0f814063-cmf81d0f814060.cpe.net.cable.rogers.com ([174.114.57.56]:57720 helo=localhost.localdomain) by cpanel4.indieserve.net with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91) (envelope-from ) id 1ftwmg-008hGk-Df for netdev@vger.kernel.org; Sun, 26 Aug 2018 11:16:59 -0400 Sender: netdev-owner@vger.kernel.org List-ID: 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 -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca/dokuwiki Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================