On Tue, Aug 11, 2020 at 10:24 AM Cong Wang <xiyou.wangcong@xxxxxxxxx> wrote: > > On Mon, Aug 10, 2020 at 6:16 PM Tonghao Zhang <xiangxia.m.yue@xxxxxxxxx> wrote: > > Hi all, I send a patch to fix this. The rcu warnings disappear. I > > don't reproduce the double free issue. > > But I guess this patch may address this issue. > > > > http://patchwork.ozlabs.org/project/netdev/patch/20200811011001.75690-1-xiangxia.m.yue@xxxxxxxxx/ > > I don't see how your patch address the double-free, as we still > free mask array twice after your patch: once in tbl_mask_array_realloc() > and once in ovs_flow_tbl_destroy(). Hi Cong. Before my patch, we use the ovsl_dereference (rcu_dereference_protected) in the rcu callback. ovs_flow_tbl_destroy ->table_instance_destroy ->table_instance_flow_free ->flow_mask_remove ASSERT_OVSL(will print warning) ->tbl_mask_array_del_mask ovsl_dereference(rcu usage warning) so we should invoke the table_instance_destroy or others under ovs_lock to avoid (ASSERT_OVSL and rcu usage warning). with this patch, we reallocate the mask_array under ovs_lock, and free it in the rcu callback. Without it, we reallocate and free it in the rcu callback. I think we may fix it with this patch. > Have you tried my patch which is supposed to address this double-free? I don't reproduce it. but your patch does not avoid ruc usage warning and ASSERT_OVSL. > It simply skips the reallocation as it makes no sense to trigger reallocation > when destroying it. > > Thanks. -- Best regards, Tonghao
