From: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Date: Mon, 28 Mar 2022 16:21:22 +0200
Subject: ice: xsk: Stop Rx processing when ntc catches ntu
Patch-mainline: v5.18-rc1
Git-commit: 0ec1713009c5cc24244c918def1cd14080be27e3
References: jsc#PED-376

This can happen with big budget values and some breakage of re-filling
descriptors as we do not clear the entry that ntu is pointing at the end
of ice_alloc_rx_bufs_zc. So if ntc is at ntu then it might be the case
that status_error0 has an old, uncleared value and ntc would go over
with processing which would result in false results.

Break Rx loop when ntc == ntu to avoid broken behavior.

Fixes: 3876ff525de7 ("ice: xsk: Handle SW XDP ring wrap and bump tail more often")
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220328142123.170157-4-maciej.fijalkowski@intel.com
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/intel/ice/ice_xsk.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/net/ethernet/intel/ice/ice_xsk.c
+++ b/drivers/net/ethernet/intel/ice/ice_xsk.c
@@ -608,6 +608,9 @@ int ice_clean_rx_irq_zc(struct ice_rx_ri
 		 */
 		dma_rmb();
 
+		if (unlikely(rx_ring->next_to_clean == rx_ring->next_to_use))
+			break;
+
 		xdp = *ice_xdp_buf(rx_ring, rx_ring->next_to_clean);
 
 		size = le16_to_cpu(rx_desc->wb.pkt_len) &