From 379169740b0a955972cebb4994b2607b264a4b41 Mon Sep 17 00:00:00 2001 From: Maxim Mikityanskiy Date: Mon, 4 Apr 2022 21:51:15 +0300 Subject: [PATCH] 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: ea5d49bdae8b ("net/mlx5e: Add XDP multi buffer support to the non-linear legacy RQ") Signed-off-by: Maxim Mikityanskiy Reviewed-by: Tariq Toukan Signed-off-by: Saeed Mahameed --- drivers/net/ethernet/mellanox/mlx5/core/en/trap.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/trap.c b/drivers/net/ethernet/mellanox/mlx5/core/en/trap.c index a55b066746cb..857840ab1e91 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en/trap.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/trap.c @@ -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; }