On Sat, 7 Jul 2012 20:38:23 +0000 Bjoern A. Zeeb wrote: BAZ> On 6. Jul 2012, at 05:53 , Mikolaj Golub wrote:
>> >> On Thu, 5 Jul 2012 20:21:53 +0000 Bjoern A. Zeeb wrote: >> >> BAZ> On 5. Jul 2012, at 19:53 , Mikolaj Golub wrote: >> >>>> >>>> On Thu, 05 Jul 2012 12:18:20 -0700 Xin Li wrote: >>>> >>>> XL> Hi, Mikolaj, >>>> >>>> XL> On 07/04/12 00:00, Mikolaj Golub wrote: >>>>>> Is this observed after destroying epair? There is an issue with >>>>>> epair: on destroy, when epair_clone_destroy() calls >>>>>> ether_ifdetach() for its second half it does not switch to its vnet >>>>>> and if_detach_internal() can't find the interface and just returns. >>>>>> As a result V_ifnet list is left with dead reference. >>>> >>>> XL> Yes. >>>> >>>>>> http://lists.freebsd.org/pipermail/freebsd-virtualization/2011-January/000628.html >>>>>> >>>>>> Here is an updated patch against CURRENT: >>>>>> >>>>>> http://people.freebsd.org/~trociny/if_epair.c.epair_clone_destroy.1.patch >>>> >>>> XL> Your >>>>>> >>>> XL> patch did fixed the problem, thanks! Are you going to commit it >>>> XL> against -HEAD and then MFC after a while? >>>> >>>> I would like Bjoern review it before me committing, or at least tell he >>>> does >>>> not mind, if he does not have time to review -) >> >> BAZ> To me the patch looks wrong; I am wondering if someone broke some >> other central >> BAZ> assumptions but given I cannot currently spend time on this and if it >> fixes things >> BAZ> feel free to go ahead. >> >> If you told what looks wrong I could try to dig at that direction and might >> be >> back with a better solution, instead of committing a presumably wrong fix. BAZ> sorry; vnet.c:vnet_destroy() should dtrt already wrt to interfaces moving to parents BAZ> and being detached. But this is not the issue with vnet_destroy() not moving interfaces to parents. It does move them. It is with destroying epair. When epair that has its ends in different vnets is destroyed, and ether_ifdetach() is called for the second end without switching to its vnet it fails to find the iface in the wrong vnet and just silently returns (which I think is also wrong: if_detach_internal() should panic here). As a result the pointer is not removed from vnet ifnet list. And later, when someone is traversing this list and tries to access the pointer (this is often vnet_destroy(), which is usually called after removing interfaces, but might be e.g. ifconfig) dead pointer dereference occurs. My patch just makes epair_clone_destroy() switch to the proper vnet before calling ether_ifdetach(). Or have I missed your point? -- Mikolaj Golub _______________________________________________ freebsd-virtualization@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-virtualization To unsubscribe, send any mail to "freebsd-virtualization-unsubscr...@freebsd.org"
