From 366cbf2f46048d70005c6c33dc289330f24b54b0 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 30 Nov 2016 22:16:06 +0100 Subject: bpf, xdp: drop rcu_read_lock from bpf_prog_run_xdp and move to caller After 326fe02d1ed6 ("net/mlx4_en: protect ring->xdp_prog with rcu_read_lock"), the rcu_read_lock() in bpf_prog_run_xdp() is superfluous, since callers need to hold rcu_read_lock() already to make sure BPF program doesn't get released in the background. Thus, drop it from bpf_prog_run_xdp(), as it can otherwise be misleading. Still keeping the bpf_prog_run_xdp() is useful as it allows for grepping in XDP supported drivers and to keep the typecheck on the context intact. For mlx4, this means we don't have a double rcu_read_lock() anymore. nfp can just make use of bpf_prog_run_xdp(), too. For qede, just move rcu_read_lock() out of the helper. When the driver gets atomic replace support, this will move to call-sites eventually. mlx5 needs actual fixing as it has the same issue as described already in 326fe02d1ed6 ("net/mlx4_en: protect ring->xdp_prog with rcu_read_lock"), that is, we're under RCU bh at this time, BPF programs are released via call_rcu(), and call_rcu() != call_rcu_bh(), so we need to properly mark read side as programs can get xchg()'ed in mlx5e_xdp_set() without queue reset. Fixes: 86994156c736 ("net/mlx5e: XDP fast RX drop bpf programs support") Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Acked-by: Jakub Kicinski Signed-off-by: David S. Miller --- drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'drivers/net/ethernet/mellanox/mlx5') diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c index b036710ba52c..42cd687e6608 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c @@ -737,10 +737,10 @@ static inline struct sk_buff *skb_from_cqe(struct mlx5e_rq *rq, struct mlx5_cqe64 *cqe, u16 wqe_counter, u32 cqe_bcnt) { - struct bpf_prog *xdp_prog = READ_ONCE(rq->xdp_prog); struct mlx5e_dma_info *di; struct sk_buff *skb; void *va, *data; + bool consumed; di = &rq->dma_info[wqe_counter]; va = page_address(di->page); @@ -759,7 +759,11 @@ struct sk_buff *skb_from_cqe(struct mlx5e_rq *rq, struct mlx5_cqe64 *cqe, return NULL; } - if (mlx5e_xdp_handle(rq, xdp_prog, di, data, cqe_bcnt)) + rcu_read_lock(); + consumed = mlx5e_xdp_handle(rq, READ_ONCE(rq->xdp_prog), di, data, + cqe_bcnt); + rcu_read_unlock(); + if (consumed) return NULL; /* page/packet was consumed by XDP */ skb = build_skb(va, RQ_PAGE_SIZE(rq)); -- cgit v1.2.3