Re: [PATCH net-next 8/9] sit: convert configuration to RCU protection

On Mon, Sep 7, 2026 at 4:33 PM Lorenzo Bianconi
[off-list ref] wrote:

quoted

Now that SIT parameters are dynamically allocated, convert
tunnel->sit_parms to an RCU-protected pointer.

Updates in ipip6_tunnel_update() allocate a new parameter block,
publish it using rcu_assign_pointer(), and free the old one
via kfree_rcu().

We only need to unlink and re-link the tunnel in the hash table
if either saddr or daddr changed. When neither address changes,
the unhash/re-hash and synchronize_net() can be completely skipped.

Readers in ipip6_tunnel_lookup(), ipip6_tunnel_xmit(), ipip6_err(),
and ipip6_rcv() now safely dereference tunnel->sit_parms under RCU.

I think this patch is fine, I am just wondering if we can use more generic name
with respect to 'sit_parms' since I guess we have the same issue for IPIP and
IP6IP6 tunnels. Do you prefer to have dedicated pointers for them?

Name could be more generic indeed.

I was thinking of using a union for future tunnel conversions.

Acked-by: Lorenzo Bianconi <redacted>

Regards,
Lorenzo