Commit 37916974 authored by Maxim Mikityanskiy's avatar Maxim Mikityanskiy Committed by Saeed Mahameed
Browse files

net/mlx5e: Wrap mlx5e_trap_napi_poll into rcu_read_lock 



The body of mlx5e_napi_poll is wrapped into rcu_read_lock to be able to
read the XDP program pointer using rcu_dereference. However, the trap RQ
NAPI doesn't use rcu_read_lock, because the trap RQ works only in the
non-linear mode, and mlx5e_skb_from_cqe_nonlinear, until recently,
didn't support XDP and didn't call rcu_dereference.

Starting from the cited commit, mlx5e_skb_from_cqe_nonlinear supports
XDP and calls rcu_dereference, but mlx5e_trap_napi_poll doesn't wrap it
into rcu_read_lock. It leads to RCU-lockdep warnings like this:

    WARNING: suspicious RCU usage

This commit fixes the issue by adding an rcu_read_lock to
mlx5e_trap_napi_poll, similarly to mlx5e_napi_poll.

Fixes: ea5d49bd ("net/mlx5e: Add XDP multi buffer support to the non-linear legacy RQ")
Signed-off-by: default avatarMaxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: default avatarTariq Toukan <tariqt@nvidia.com>
Signed-off-by: default avatarSaeed Mahameed <saeedm@nvidia.com>
parent 785d7ed2

drivers/net/ethernet/mellanox/mlx5/core/en/trap.c

+10 −3
Original line number Diff line number Diff line
@@ -14,19 +14,26 @@ static int mlx5e_trap_napi_poll(struct napi_struct *napi, int budget) 
	bool busy = false;

	int work_done = 0;



	rcu_read_lock();



	ch_stats->poll++;



	work_done = mlx5e_poll_rx_cq(&rq->cq, budget);

	busy |= work_done == budget;

	busy |= rq->post_wqes(rq);



	if (busy)

		return budget;

	if (busy) {

		work_done = budget;

		goto out;

	}



	if (unlikely(!napi_complete_done(napi, work_done)))

		return work_done;

		goto out;



	mlx5e_cq_arm(&rq->cq);



out:

	rcu_read_unlock();

	return work_done;

}