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Date: Fri, 15 May 2009 12:33:39 -0400 From: Chase Douglas <chasedouglas.lists@...il.com> To: netdev@...r.kernel.org Subject: neigh_params_release() usage in net/ipv6/addrconf.c I'm debugging an issue I'm seeing when I use vlan with IPv6 support. After bringing up the device, I'm unable to bring it down and unregister it. I put some debug statements around dev_hold() and dev_put() to see what was going on: dev_hold() called on lo.2, new refcnt: 1 (net/core/dev.c:4162) dev_hold() called on lo.2, new refcnt: 2 (net/core/neighbour.c:1357) dev_hold() called on lo.2, new refcnt: 3 (net/ipv4/devinet.c:178) dev_hold() called on lo.2, new refcnt: 4 (net/core/neighbour.c:1357) dev_hold() called on lo.2, new refcnt: 5 (net/8021q/vlan.c:266) dev_hold() called on lo.2, new refcnt: 6 (net/core/link_watch.c:219) dev_put() called on lo.2, new refcnt: 5 (net/core/link_watch.c:191) dev_hold() called on lo.2, new refcnt: 6 (net/core/dev.c:684) dev_put() called on lo.2, new refcnt: 5 (net/ipv4/fib_semantics.c:149) dev_hold() called on lo.2, new refcnt: 6 (net/core/dev.c:684) dev_hold() called on lo.2, new refcnt: 7 (net/ipv4/fib_frontend.c:173) dev_put() called on lo.2, new refcnt: 6 (net/ipv4/route.c:2453) dev_put() called on lo.2, new refcnt: 5 (net/ipv4/fib_semantics.c:149) dev_put() called on lo.2, new refcnt: 4 (net/core/neighbour.c:1393) dev_put() called on lo.2, new refcnt: 3 (net/ipv4/devinet.c:151) dev_put() called on lo.2, new refcnt: 2 (net/core/dev.c:4010) dev_put() called on lo.2, new refcnt: 1 (net/8021q/vlan.c:182) unregister_netdevice: waiting for lo.2 to become free. Usage count = 2 The fourth dev_hold() is in neigh_parms_alloc(), called by ipv6_add_dev(). The only place I see neigh_parms_release() called in addrconf.c is if ipv6_add_dev() fails later on, or when taking the device down in addrconf_ifdown(). Unfortunately, when I bring the vlan dev down I never see addrconf_ifdown() called with the how parameter set to 1, which is the only instance where neigh_parms_release() would be called. Why is neigh_parms_release() called in addrconf_ifdown() instead of in6_dev_finish_destroy(), which looks to me to be the complement of ipv6_add_dev()? If neigh_parms_release() really should be called in addrconf_ifdown(), does anyone know why it's not being called properly in this instance? PS: I am running my tests using a slightly modified SLES 11 kernel. I haven't been able to find anything in the git trees that would indicate to me that the problem has been fixed upstream. -- 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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