From: Björn Töpel Date: Fri, 11 Dec 2020 14:57:12 +0000 (+0100) Subject: i40e, xsk: clear the status bits for the next_to_use descriptor X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=64050b5b8706d304ba647591b06e1eddc55e8bd9;p=linux.git i40e, xsk: clear the status bits for the next_to_use descriptor On the Rx side, the next_to_use index points to the next item in the HW ring to be refilled/allocated, and next_to_clean points to the next item to potentially be processed. When the HW Rx ring is fully refilled, i.e. no packets has been processed, the next_to_use will be next_to_clean - 1. When the ring is fully processed next_to_clean will be equal to next_to_use. The latter case is where a bug is triggered. If the next_to_use bits are not cleared, and the "fully processed" state is entered, a stale descriptor can be processed. The skb-path correctly clear the status bit for the next_to_use descriptor, but the AF_XDP zero-copy path did not do that. This change adds the status bits clearing of the next_to_use descriptor. Fixes: 3b4f0b66c2b3 ("i40e, xsk: Migrate to new MEM_TYPE_XSK_BUFF_POOL") Signed-off-by: Björn Töpel Signed-off-by: Jakub Kicinski --- diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c index bfa84bfb04880..47eb9c584a123 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c +++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c @@ -220,8 +220,11 @@ bool i40e_alloc_rx_buffers_zc(struct i40e_ring *rx_ring, u16 count) } while (count); no_buffers: - if (rx_ring->next_to_use != ntu) + if (rx_ring->next_to_use != ntu) { + /* clear the status bits for the next_to_use descriptor */ + rx_desc->wb.qword1.status_error_len = 0; i40e_release_rx_desc(rx_ring, ntu); + } return ok; }