On Wed, Jul 1, 2026 at 5:50 AM Eric Dumazet [off-list ref] wrote:

Update amt_fill_info() to run under RCU read lock instead of RTNL.

The AMT device configuration fields (mode, relay_port, gw_port, local_ip,
discovery_ip, max_tunnels) and stream_dev pointer are initialized during
device creation (amt_newlink) and are immutable. Accessing them locklessly
is safe. The stream_dev net_device structure is protected from being freed
by RCU.

The only field that can change concurrently is amt->remote_ip, which is
updated in the packet receive path (amt_advertisement_handler) and
workqueue (amt_req_work). Add READ_ONCE()/WRITE_ONCE() annotations
around amt->remote_ip to prevent data races.

Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>