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Date: Sun, 28 Aug 2011 16:09:49 +0200 From: Eric Dumazet <eric.dumazet@...il.com> To: HAYASAKA Mitsuo <mitsuo.hayasaka.hu@...achi.com> Cc: Herbert Xu <herbert@...dor.apana.org.au>, Stephen Hemminger <shemminger@...tta.com>, Patrick McHardy <kaber@...sh.net>, "David S. Miller" <davem@...emloft.net>, MichałMirosław <mirq-linux@...e.qmqm.pl>, Tom Herbert <therbert@...gle.com>, Jesse Gross <jesse@...ira.com>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, yrl.pp-manager.tt@...achi.com Subject: Re: [PATCH net-next ] Fix time-lag of IFF_RUNNING flag consistency between vlan and real devices Le dimanche 28 août 2011 à 22:20 +0900, HAYASAKA Mitsuo a écrit : > Hi Stephen and Herbert > > Thank you for your comments. > > (2011/08/26 15:08), Stephen Hemminger wrote: > > I don't think this is the right way to solve the problem. > > > > The flags are supposed to propagate back from real device to vlan > > via network notifications. > > > > Just doing this for ioctl is not enough, API's other than user space depend on this. > > Also the user may have manually set different flags on vlan than on > > the real device. > > I agreed. > I will try another way to solve this problem, as you said. > > > (2011/08/26 15:45), Herbert Xu wrote: > > On Thu, Aug 25, 2011 at 11:08:59PM -0700, Stephen Hemminger wrote: > >> Just doing this for ioctl is not enough, API's other than user space depend on this. > >> Also the user may have manually set different flags on vlan than on > >> the real device. > > Right, anything that tests netif_carrier_ok directly on the VLAN > > device will still be delayed. > > > > Now I remember discussing this issue in Japan. However, I can't > > recall the exact scenario in which the delay occured. > > > > Is the issue with the link status going down on the real device, > > or the real device coming up? > > > > IIRC we already have mechanisms in place to ensure that down events > > are not delayed by linkwatch. Of course it is possible that this > > isn't working for some reason, or some other part of the system is > > causing the delay. > > > > So please clarify the scenario for us Hayasaka-san. Also please > > let us know how you measured the delay. > > > > Thanks, > > This issue happens when the link status is going down on the real > device. > > ex) A cable is broken, or is unplugged from a NIC. > > I measured the delay using ioctl with SIOCGIFFLAGS from userspace > in order to check if there is a time-lag of the flag between vlan > and real devices. > > Also, you can check it using a script below. > > ------------------------- > #!/bin/sh > t=0 > while : > do > echo $t; t=$((t+1)) > echo -n real; ifconfig RealDev | grep UP > echo -n vlan; ifconfig VlanDev | grep UP > sleep 0.2 > done > ------------------------- > > The result is shown as follows. > It is observed that there is a time-lag of RUNNING status between > real and vlan devices. > > Hi ! This reminds me some work done in linkwatch Please take a look at commit e014debecd3ee3832e647 (linkwatch: linkwatch_forget_dev() to speedup device dismantle) And more generally, code in net/core/link_watch.c -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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