Message ID | 1344546593.2593.24.camel@bwh-desktop.uk.solarflarecom.com |
---|---|
State | RFC, archived |
Delegated to: | David Miller |
Headers | show |
Ben Hutchings <bhutchings@solarflare.com> wrote: >On Thu, 2012-08-09 at 21:55 +0200, Jiri Pirko wrote: [...] >> How about other devices who do not use "->master" like vlan, macvlan? > >And they shouldn't use master, because they allow multiple upper devices >may be stacked on a single lower device. Instead they use iflink, but >that's an ifindex and not a net_device pointer. > >So I think we can catch simple loops with: > >--- a/net/core/dev.c >+++ b/net/core/dev.c >@@ -4445,8 +4445,22 @@ int netdev_set_master(struct net_device *slave, struct net_device *master) > ASSERT_RTNL(); > > if (master) { >+ struct net_device *bottom, *top; >+ > if (old) > return -EBUSY; >+ >+ /* Prevent loops */ >+ bottom = slave; >+ while (bottom->iflink != bottom->ifindex) >+ bottom = __dev_get_by_index(dev_net(bottom), >+ bottom->iflink); >+ top = master; >+ while (top->master) >+ top = top->master; >+ if (top == bottom) >+ return -EBUSY; >+ > dev_hold(master); > } > >--- END --- > >But then there can be quite silly device relationships like: > > +-------+ > | bond0 | > ++-----++ > / \ >+-------+ +---+---+ +---+---+ +-------+ >| vlan0 | | vlan1 | | vlan2 | | vlan3 | >+---+---+ +---+---+ +---+---+ +---+---+ > \ / \ / > ++-----++ ++--+--++ > | bond1 | | bond2 | > +-------+ +-------+ > : : : : > >Suppose the user tries to make bond0 a slave of bond1; we need to go to >somewhat more effort to detect the loop. If that's hard to do (and it might be; I'm not aware of a standard way to run up and down those stacks of interfaces, which might not always be vlans in the middle), there's still the priv_flags & IFF_BONDING test that bonding could (and probably should) do itself as well. The team driver could presumably have a similar test, although I seem to recall that team was allowed to nest. FWIW, I've seen both the top and bottom halves of that picture in use (i.e., bonds consisting of vlans as slaves or bonds with vlans configured above them), but not combined as in your diagram. -J --- -Jay Vosburgh, IBM Linux Technology Center, fubar@us.ibm.com -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Jay Vosburgh <fubar@us.ibm.com> Date: Thu, 09 Aug 2012 14:27:08 -0700 > If that's hard to do (and it might be; I'm not aware of a > standard way to run up and down those stacks of interfaces, which might > not always be vlans in the middle), there's still the priv_flags & > IFF_BONDING test that bonding could (and probably should) do itself as > well. The team driver could presumably have a similar test, although I > seem to recall that team was allowed to nest. > > FWIW, I've seen both the top and bottom halves of that picture > in use (i.e., bonds consisting of vlans as slaves or bonds with vlans > configured above them), but not combined as in your diagram. We're basically looking for cycles in a complex graph. Some combination of Jay and Ben's most recent patches, with some minor modifications, ought to do it. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Fri, Aug 10, 2012 at 01:43:31AM CEST, davem@davemloft.net wrote: >From: Jay Vosburgh <fubar@us.ibm.com> >Date: Thu, 09 Aug 2012 14:27:08 -0700 > >> If that's hard to do (and it might be; I'm not aware of a >> standard way to run up and down those stacks of interfaces, which might >> not always be vlans in the middle), there's still the priv_flags & >> IFF_BONDING test that bonding could (and probably should) do itself as >> well. The team driver could presumably have a similar test, although I >> seem to recall that team was allowed to nest. >> >> FWIW, I've seen both the top and bottom halves of that picture >> in use (i.e., bonds consisting of vlans as slaves or bonds with vlans >> configured above them), but not combined as in your diagram. > >We're basically looking for cycles in a complex graph. > >Some combination of Jay and Ben's most recent patches, with some minor >modifications, ought to do it. Hmm. Would be probably good to have list/table of related devices, possibly with information about the relation. After that, every relation add would check for loops. I will dive in the code over the weekend to see if this is doable in some nice way. >-- >To unsubscribe from this list: send the line "unsubscribe netdev" in >the body of a message to majordomo@vger.kernel.org >More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- a/net/core/dev.c +++ b/net/core/dev.c @@ -4445,8 +4445,22 @@ int netdev_set_master(struct net_device *slave, struct net_device *master) ASSERT_RTNL(); if (master) { + struct net_device *bottom, *top; + if (old) return -EBUSY; + + /* Prevent loops */ + bottom = slave; + while (bottom->iflink != bottom->ifindex) + bottom = __dev_get_by_index(dev_net(bottom), + bottom->iflink); + top = master; + while (top->master) + top = top->master; + if (top == bottom) + return -EBUSY; + dev_hold(master); } --- END ---