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Subject[PATCH net] net: hns3: fix for not calculating tx bd num correctly
Date
From: Yunsheng Lin <linyunsheng@huawei.com>

When there is only one byte in a frag, the current calculation
using "(size + HNS3_MAX_BD_SIZE - 1) >> HNS3_MAX_BD_SIZE_OFFSET"
will return zero, because HNS3_MAX_BD_SIZE is 65535 and
HNS3_MAX_BD_SIZE_OFFSET is 16. So it will cause tx error when
a frag's size is one byte.

This patch fixes it by using DIV_ROUND_UP.

Fixes: 3fe13ed95dd3 ("net: hns3: avoid mult + div op in critical data path")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
---
drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 13 ++++++-------
drivers/net/ethernet/hisilicon/hns3/hns3_enet.h | 1 -
2 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
index 1c1f17e..162cb9a 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
@@ -22,6 +22,7 @@
#include "hns3_enet.h"

#define hns3_set_field(origin, shift, val) ((origin) |= ((val) << (shift)))
+#define hns3_tx_bd_count(S) DIV_ROUND_UP(S, HNS3_MAX_BD_SIZE)

static void hns3_clear_all_ring(struct hnae3_handle *h);
static void hns3_force_clear_all_rx_ring(struct hnae3_handle *h);
@@ -1079,7 +1080,7 @@ static int hns3_fill_desc(struct hns3_enet_ring *ring, void *priv,

desc_cb->length = size;

- frag_buf_num = (size + HNS3_MAX_BD_SIZE - 1) >> HNS3_MAX_BD_SIZE_OFFSET;
+ frag_buf_num = hns3_tx_bd_count(size);
sizeoflast = size & HNS3_TX_LAST_SIZE_M;
sizeoflast = sizeoflast ? sizeoflast : HNS3_MAX_BD_SIZE;

@@ -1124,14 +1125,13 @@ static int hns3_nic_maybe_stop_tso(struct sk_buff **out_skb, int *bnum,
int i;

size = skb_headlen(skb);
- buf_num = (size + HNS3_MAX_BD_SIZE - 1) >> HNS3_MAX_BD_SIZE_OFFSET;
+ buf_num = hns3_tx_bd_count(size);

frag_num = skb_shinfo(skb)->nr_frags;
for (i = 0; i < frag_num; i++) {
frag = &skb_shinfo(skb)->frags[i];
size = skb_frag_size(frag);
- bdnum_for_frag = (size + HNS3_MAX_BD_SIZE - 1) >>
- HNS3_MAX_BD_SIZE_OFFSET;
+ bdnum_for_frag = hns3_tx_bd_count(size);
if (unlikely(bdnum_for_frag > HNS3_MAX_BD_PER_FRAG))
return -ENOMEM;

@@ -1139,8 +1139,7 @@ static int hns3_nic_maybe_stop_tso(struct sk_buff **out_skb, int *bnum,
}

if (unlikely(buf_num > HNS3_MAX_BD_PER_FRAG)) {
- buf_num = (skb->len + HNS3_MAX_BD_SIZE - 1) >>
- HNS3_MAX_BD_SIZE_OFFSET;
+ buf_num = hns3_tx_bd_count(skb->len);
if (ring_space(ring) < buf_num)
return -EBUSY;
/* manual split the send packet */
@@ -1169,7 +1168,7 @@ static int hns3_nic_maybe_stop_tx(struct sk_buff **out_skb, int *bnum,
buf_num = skb_shinfo(skb)->nr_frags + 1;

if (unlikely(buf_num > HNS3_MAX_BD_PER_FRAG)) {
- buf_num = (skb->len + HNS3_MAX_BD_SIZE - 1) / HNS3_MAX_BD_SIZE;
+ buf_num = hns3_tx_bd_count(skb->len);
if (ring_space(ring) < buf_num)
return -EBUSY;
/* manual split the send packet */
diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h
index 1db0bd4..75669cd 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h
@@ -193,7 +193,6 @@ enum hns3_nic_state {
#define HNS3_VECTOR_INITED 1

#define HNS3_MAX_BD_SIZE 65535
-#define HNS3_MAX_BD_SIZE_OFFSET 16
#define HNS3_MAX_BD_PER_FRAG 8
#define HNS3_MAX_BD_PER_PKT MAX_SKB_FRAGS

--
2.8.1
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