[dpdk-dev] [PATCH] net/thunderx: fix Tx desc corruption in scatter-gather mode

[Nithin Dabilpuram <nithin.dabilpuram@caviumnetworks.com>]

From: Subrahmanyam Nilla <snilla@caviumnetworks.com>

For performance reasons, word1 of send_hdr_s
sub descriptor was not cleared assuming it is always
having default value of zero since it comes from fixed
offsets of SQ buffer.
This is causing issues in case of SG mode because,
the size of send command might change and hence the word1
of send_hdr_s is not always at fixed offsets of the SQ buffer
and hence not having default value of zero.

This fixes the issue by clearing the word1 in case of SG mode
for every packet.

Fixes: 1c421f18e0 ("net/thunderx: add single and multi-segment Tx")
Cc: stable@dpdk.org

Signed-off-by: Subrahmanyam Nilla <snilla@caviumnetworks.com>
Signed-off-by: Nithin Dabilpuram <ndabilpuram@caviumnetworks.com>
---
 drivers/net/thunderx/nicvf_rxtx.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/net/thunderx/nicvf_rxtx.c b/drivers/net/thunderx/nicvf_rxtx.c
index 247c356..1c42874 100644
--- a/drivers/net/thunderx/nicvf_rxtx.c
+++ b/drivers/net/thunderx/nicvf_rxtx.c
@@ -61,6 +61,14 @@
 	entry->buff[0] = sqe.buff[0];
 }
 
+static inline void __hot
+fill_sq_desc_header_zero_w1(union sq_entry_t *entry,
+				struct rte_mbuf *pkt)
+{
+	fill_sq_desc_header(entry, pkt);
+	entry->buff[1] = 0ULL;
+}
+
 void __hot
 nicvf_single_pool_free_xmited_buffers(struct nicvf_txq *sq)
 {
@@ -204,7 +212,7 @@
 		used_bufs += nb_segs;
 
 		txbuffs[tail] = NULL;
-		fill_sq_desc_header(desc_ptr + tail, pkt);
+		fill_sq_desc_header_zero_w1(desc_ptr + tail, pkt);
 		tail = (tail + 1) & qlen_mask;
 
 		txbuffs[tail] = pkt;
-- 
1.8.3.1