On Tue, Mar 05, 2019 at 11:15:06PM -0800, si-wei liu wrote: > > > On 3/5/2019 10:43 PM, Michael S. Tsirkin wrote: > > On Tue, Mar 05, 2019 at 04:51:00PM -0800, si-wei liu wrote: > > > > > > On 3/5/2019 4:36 PM, Michael S. Tsirkin wrote: > > > > On Tue, Mar 05, 2019 at 04:20:50PM -0800, si-wei liu wrote: > > > > > On 3/5/2019 4:06 PM, Michael S. Tsirkin wrote: > > > > > > On Tue, Mar 05, 2019 at 11:35:50AM -0800, si-wei liu wrote: > > > > > > > On 3/5/2019 11:24 AM, Stephen Hemminger wrote: > > > > > > > > On Tue, 5 Mar 2019 11:19:32 -0800 > > > > > > > > si-wei liu <si-wei.liu@xxxxxxxxxx> wrote: > > > > > > > > > > > > > > > > > > I have a vague idea: would it work to *not* set > > > > > > > > > > IFF_UP on slave devices at all? > > > > > > > > > Hmm, I ever thought about this option, and it appears this solution is > > > > > > > > > more invasive than required to convert existing scripts, despite the > > > > > > > > > controversy of introducing internal netdev state to differentiate user > > > > > > > > > visible state. Either we disallow slave to be brought up by user, or to > > > > > > > > > not set IFF_UP flag but instead use the internal one, could end up with > > > > > > > > > substantial behavioral change that breaks scripts. Consider any admin > > > > > > > > > script that does `ip link set dev ... up' successfully just assumes the > > > > > > > > > link is up and subsequent operation can be done as usual. > > > > > > How would it work when carrier is off? > > > > > > > > > > > > > While it *may* > > > > > > > > > work for dracut (yet to be verified), I'm a bit concerned that there are > > > > > > > > > more scripts to be converted than those that don't follow volatile > > > > > > > > > failover slave names. It's technically doable, but may not worth the > > > > > > > > > effort (in terms of porting existing scripts/apps). > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > -Siwei > > > > > > > > Won't work for most devices. Many devices turn off PHY and link layer > > > > > > > > if not IFF_UP > > > > > > > True, that's what I said about introducing internal state for those driver > > > > > > > and other kernel component. Very invasive change indeed. > > > > > > > > > > > > > > -Siwei > > > > > > Well I did say it's vague. > > > > > > How about hiding IFF_UP from dev_get_flags (and probably > > > > > > __dev_change_flags)? > > > > > > > > > > > Any different? This has small footprint for the kernel change for sure, > > > > > while the discrepancy is still there. Anyone who writes code for IFF_UP will > > > > > not notice IFF_FAILOVER_SLAVE. > > > > > > > > > > Not to mention more userspace "fixup" work has to be done due to this > > > > > change. > > > > > > > > > > -Siwei > > > > > > > > > > > > > > Point is it's ok since most userspace should just ignore slaves > > > > - hopefully it will just ignore it since it already > > > > ignores interfaces that are down. > > > Admin script thought the interface could be bright up and do further > > > operations without checking the UP flag. > > These scripts then would be broken on any box with multiple interfaces > > since not all of these would have carrier. > Consider a script executing `ifconfig ... up' and once succeeds runs tcpdump > or some other command relying on UP interface. It's quite common that those > scripts don't check the UP flag but instead just rely on the well-known fact > that the command exits with 0 meaning the interface should be UP. This > change might well break scripts of that kind. I am sorry I don't get it. Could you give an example of a script that works now but would be broken? > > > > > > > It doesn't look to be a reliable > > > way of prohibit userspace from operating against slaves. > > > > > > -Siwei > > > > > > > > This does not mean we shouldn't make an effort to disable broken > > configurations. > > > > I am not arguing against your patch. Not at all. I see better > > hiding of slaves as a separate enhancement. > I understand, but my point is we should try to minimize unnecessary side > impact to the current usage for whatever "hiding" effort we can make. It's > hard to find a tradeoff sometimes. Yes if some userspace made an assumption and it worked, we should keep it working I think. I don't necessarily agree we should worry too much about theoretical issues. In half a year since the feature got merged it's unlikely there are millions of slightly different scripts using it. > > > > > > Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > > > > > Thank you. > > -Siwei _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
