ice: xsk: Stop Rx processing when ntc catches ntu

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

diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c
index 51427cb..dfbcaf0 100644 (file)
--- 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_ring *rx_ring, int budget)
                 */
                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) &