Re: [PATCH net-next 0/3] vxlan: RCU protect vxlan_config and enable RTNL-less fill_info

[Paolo Abeni <pabeni@redhat.com>]

On 7/10/26 4:20 PM, Paolo Abeni wrote:
> On 7/8/26 6:04 PM, Eric Dumazet wrote:
>> This patch series converts VXLAN configuration (`struct vxlan_config`)
>> to be RCU-protected, allowing lockless readers and enabling RTNL-less
>> `vxlan_fill_info()` netlink link info dumping.
>>
>> Work has been split into three distinct parts:
>>
>> 1. Refactor helper functions in RX, TX, MDB, VNIFILTER, and OVS paths to
>>    accept a `const struct vxlan_config *cfg` pointer (or pass specific
>>    fields such as `flags`/`saddr_family`) rather than accessing
>>    `vxlan->cfg` directly.
>>
>> 2. Convert `vxlan->cfg` from an embedded struct into an RCU-protected
>>    pointer (`struct vxlan_config __rcu *cfg`), dynamically allocated on
>>    device creation or changelink, and freed via `kfree_rcu()`. Update
>>    offload drivers (`mlxsw`) and OVS (`vport-vxlan.c`) accordingly.
>>
>> 3. Update `vxlan_fill_info()` to run under `rcu_read_lock()` instead of
>>    relying on RTNL lock, completing the transition to lockless link info
>>    dumping for VXLAN devices.
>
> I *suspect* this is triggering RCU splat in forwarding self-tests:
> 
> [ 1955.481960][T11074] =============================
oops, sashiko already spotted it:

https://sashiko.dev/#/patchset/20260708160411.1355008-1-edumazet%40google.com

/P