[PATCH 1/6] net/i40e: remove incorrect 16B descriptor read block

[Bruce Richardson]

By default, the driver works with 32B descriptors, but has a separate
descriptor read block for reading two descriptors at a time when using
16B descriptors. However, the 32B reads used are not guaranteed to be
atomic, which will cause issues if that is not the case on a system,
since the descriptors may be read in an undefined order.  Remove the
block, to avoid issues, and just use the regular descriptor reading path
for 16B descriptors, if that support is enabled at build time.

Fixes: dafadd73762e ("net/i40e: add AVX2 Rx function")
Cc: stable at dpdk.org

Signed-off-by: Bruce Richardson <bruce.richardson at intel.com>
---
 drivers/net/i40e/i40e_rxtx_vec_avx2.c | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/drivers/net/i40e/i40e_rxtx_vec_avx2.c b/drivers/net/i40e/i40e_rxtx_vec_avx2.c
index f468c1fd90..ce87e185f0 100644
--- a/drivers/net/i40e/i40e_rxtx_vec_avx2.c
+++ b/drivers/net/i40e/i40e_rxtx_vec_avx2.c
@@ -277,19 +277,6 @@ _recv_raw_pkts_vec_avx2(struct i40e_rx_queue *rxq, struct rte_mbuf **rx_pkts,
 #endif
 
 		__m256i raw_desc0_1, raw_desc2_3, raw_desc4_5, raw_desc6_7;
-#ifdef RTE_LIBRTE_I40E_16BYTE_RX_DESC
-		/* for AVX we need alignment otherwise loads are not atomic */
-		if (avx_aligned) {
-			/* load in descriptors, 2 at a time, in reverse order */
-			raw_desc6_7 = _mm256_load_si256((void *)(rxdp + 6));
-			rte_compiler_barrier();
-			raw_desc4_5 = _mm256_load_si256((void *)(rxdp + 4));
-			rte_compiler_barrier();
-			raw_desc2_3 = _mm256_load_si256((void *)(rxdp + 2));
-			rte_compiler_barrier();
-			raw_desc0_1 = _mm256_load_si256((void *)(rxdp + 0));
-		} else
-#endif
 		do {
 			const __m128i raw_desc7 = _mm_load_si128((void *)(rxdp + 7));
 			rte_compiler_barrier();
-- 
2.40.1