Since XDP programs are called from a NAPI poll context, the RCU
reference liveness is ensured by local_bh_disable().
Commit aeea1b86f9 ("bpf, devmap: Exclude XDP broadcast to master
device") started to call netdev_upper_get_next_dev_rcu() from this
context, but missed adding rcu_read_lock_bh_held() as a condition to the
RCU checks.
While both bh_disabled and rcu_read_lock() provide RCU protection,
lockdep complains since the check condition is insufficient [1].
Add rcu_read_lock_bh_held() as condition to help lockdep to understand
the dereference is safe, in the same way as commit 694cea395f ("bpf:
Allow RCU-protected lookups to happen from bh context").
[1]
WARNING: net/core/dev.c:8099 at netdev_upper_get_next_dev_rcu+0x96/0xd0, CPU#0: swapper/0/0
...
RIP: 0010:netdev_upper_get_next_dev_rcu+0x96/0xd0
...
<IRQ>
dev_map_enqueue_multi+0x411/0x970
xdp_do_redirect+0xdf2/0x1030
__igc_xdp_run_prog+0x6a0/0xc80
igc_poll+0x34b0/0x70b0
__napi_poll.constprop.0+0x98/0x490
net_rx_action+0x8f2/0xfa0
handle_softirqs+0x1c7/0x710
__irq_exit_rcu+0xb1/0xf0
irq_exit_rcu+0x9/0x20
common_interrupt+0x7f/0x90
</IRQ>
Signed-off-by: Kohei Enju <kohei@enjuk.jp>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20260220110922.94781-1-kohei@enjuk.jp
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
39feb171f3