From: Saeed Mahameed <sae...@dev.mellanox.co.il> Date: Wed, 24 Feb 2016 22:27:16 +0200
>>> Netdev features can be changed dynamically to off after vlan_vid_add >>> was called, thus vlan_vid_del will skip ndo_vlan_rx_kill_vid and will >>> leave the device driver with un-freed resources. >> >> Are you sure the fix isn't to make vlan_vid_add() check ->features instead >> of ->hw_features. > > This is exactly what this fix suggests, "->features" is not consistent > and can be turned ON/OFF between vlan_add/del which can leave the NIC > driver in inconsistent state ! But the user changes the setting _exactly_ to control whether these VLAN offloads occur or not. >> Should we really be trying to add VLAN filters when the user has >> turned it off? > > Well, I think it is debatable, but the current implementation is not > consistent, especially for adding vlan 0 by default and then the user > disables the vlan filter, this will cause the stack to never call the > nic ndo_vlan_rx_kill_vid for the pre added vlan 0 and vise versa call > kill_vid without add_vid, BUG ? > > So i think we have two options, use this patch, and always trust to > delegate vlan_vid_add/del to the NIC when it's HW supports it, and the > nic will be smart enough to know what to do with it (in case vlan > filter is enabled/disabled). Or, for each vlan we can remember if it > was added to the NIC or not so the stack will know whether to clean it > up or not. If automatically added VLANs are the issue, then we should specially mark it such that it will get forcefully removed regardless of feature settings. The whole point of the separation of ->hw_features and ->features is to separate what the card can do from what the user wants enabled or not. Therefore offload operations should be triggered by ->features not ->hw_features. Any test on ->hw_features that is not a validation of a ->features change request is a BIG RED FLAG and almost always a bug.
