Re: [PATCH net-next 3/6] net: mvneta: update mb bit before passing the xdp buffer to eBPF layer
From: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Date: 2020-08-20 19:43:58
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bpf
On Wed, Aug 19, 2020 at 03:13:48PM +0200, Lorenzo Bianconi wrote:
quoted hunk ↗ jump to hunk
Update multi-buffer bit (mb) in xdp_buff to notify XDP/eBPF layer and XDP remote drivers if this is a "non-linear" XDP buffer Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org> --- drivers/net/ethernet/marvell/mvneta.c | 3 +++ 1 file changed, 3 insertions(+)diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c index 832bbb8b05c8..36a3defa63fa 100644 --- a/drivers/net/ethernet/marvell/mvneta.c +++ b/drivers/net/ethernet/marvell/mvneta.c@@ -2170,11 +2170,14 @@ mvneta_run_xdp(struct mvneta_port *pp, struct mvneta_rx_queue *rxq, struct bpf_prog *prog, struct xdp_buff *xdp, u32 frame_sz, struct mvneta_stats *stats) { + struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp); unsigned int len, data_len, sync; u32 ret, act; len = xdp->data_end - xdp->data_hard_start - pp->rx_offset_correction; data_len = xdp->data_end - xdp->data; + + xdp->mb = !!sinfo->nr_frags;
But this set is not utilizing it from BPF side in any way. Personally I would like to see this as a part of work where BPF program would actually be taught how to rely on xdp->mb. Especially after John's comment in other patch.
act = bpf_prog_run_xdp(prog, xdp); /* Due xdp_adjust_tail: DMA sync for_device cover max len CPU touch */ -- 2.26.2