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Subject[PATCH V3 net-next 01/11] net: hns3: fix data race between ring->next_to_clean
Date
From: Yunsheng Lin <linyunsheng@huawei.com>

hns3_clean_tx_ring calls hns3_nic_reclaim_one_desc to clean
buffers and set ring->next_to_clean, then hns3_nic_net_xmit
reuses the cleaned buffers. But there are no memory barriers
when buffers gets recycled, so the recycled buffers can be
corrupted.

This patch uses smp_store_release to update ring->next_to_clean
and smp_load_acquire to read ring->next_to_clean to properly
hand off buffers from hns3_clean_tx_ring to hns3_nic_net_xmit.

Fixes: 76ad4f0ee747 ("net: hns3: Add support of HNS3 Ethernet Driver for hip08 SoC")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
---
drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 14 +++++++++++---
drivers/net/ethernet/hisilicon/hns3/hns3_enet.h | 7 +++++--
2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
index 176d4b9..9fdc87e 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
@@ -2214,14 +2214,22 @@ static void hns3_reuse_buffer(struct hns3_enet_ring *ring, int i)
static void hns3_nic_reclaim_one_desc(struct hns3_enet_ring *ring, int *bytes,
int *pkts)
{
- struct hns3_desc_cb *desc_cb = &ring->desc_cb[ring->next_to_clean];
+ int ntc = ring->next_to_clean;
+ struct hns3_desc_cb *desc_cb;

+ desc_cb = &ring->desc_cb[ntc];
(*pkts) += (desc_cb->type == DESC_TYPE_SKB);
(*bytes) += desc_cb->length;
/* desc_cb will be cleaned, after hnae3_free_buffer_detach*/
- hns3_free_buffer_detach(ring, ring->next_to_clean);
+ hns3_free_buffer_detach(ring, ntc);

- ring_ptr_move_fw(ring, next_to_clean);
+ if (++ntc == ring->desc_num)
+ ntc = 0;
+
+ /* This smp_store_release() pairs with smp_load_acquire() in
+ * ring_space called by hns3_nic_net_xmit.
+ */
+ smp_store_release(&ring->next_to_clean, ntc);
}

static int is_valid_clean_head(struct hns3_enet_ring *ring, int h)
diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h
index cec56a5..2b4f5ea 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h
@@ -581,8 +581,11 @@ union l4_hdr_info {

static inline int ring_space(struct hns3_enet_ring *ring)
{
- int begin = ring->next_to_clean;
- int end = ring->next_to_use;
+ /* This smp_load_acquire() pairs with smp_store_release() in
+ * hns3_nic_reclaim_one_desc called by hns3_clean_tx_ring.
+ */
+ int begin = smp_load_acquire(&ring->next_to_clean);
+ int end = READ_ONCE(ring->next_to_use);

return ((end >= begin) ? (ring->desc_num - end + begin) :
(begin - end)) - 1;
--
2.7.4
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