From 64050b5b8706d304ba647591b06e1eddc55e8bd9 Mon Sep 17 00:00:00 2001 From: Björn Töpel Date: Fri, 11 Dec 2020 15:57:12 +0100 Subject: i40e, xsk: clear the status bits for the next_to_use descriptor MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 --- drivers/net/ethernet/intel/i40e/i40e_xsk.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'drivers/net') diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c index bfa84bfb0488..47eb9c584a12 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; } -- cgit v1.2.3