6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jian Shen <shenjian15@xxxxxxxxxx>
[ Upstream commit 61a1deacc3d4fd3d57d7fda4d935f7f7503e8440 ]
Currently, the driver knocks the ring doorbell before updating
the ring->last_to_use in tx flow. if the hardware transmiting
packet and napi poll scheduling are fast enough, it may get
the old ring->last_to_use in drivers' napi poll.
In this case, the driver will think the tx is not completed, and
return directly without clear the flag __QUEUE_STATE_STACK_XOFF,
which may cause tx timeout.
Fixes: 20d06ca2679c ("net: hns3: optimize the tx clean process")
Signed-off-by: Jian Shen <shenjian15@xxxxxxxxxx>
Signed-off-by: Jijie Shao <shaojijie@xxxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
index b7b51e56b0308..71772213b4448 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
@@ -2102,8 +2102,12 @@ static void hns3_tx_doorbell(struct hns3_enet_ring *ring, int num,
*/
if (test_bit(HNS3_NIC_STATE_TX_PUSH_ENABLE, &priv->state) && num &&
!ring->pending_buf && num <= HNS3_MAX_PUSH_BD_NUM && doorbell) {
+ /* This smp_store_release() pairs with smp_load_aquire() in
+ * hns3_nic_reclaim_desc(). Ensure that the BD valid bit
+ * is updated.
+ */
+ smp_store_release(&ring->last_to_use, ring->next_to_use);
hns3_tx_push_bd(ring, num);
- WRITE_ONCE(ring->last_to_use, ring->next_to_use);
return;
}
@@ -2114,6 +2118,11 @@ static void hns3_tx_doorbell(struct hns3_enet_ring *ring, int num,
return;
}
+ /* This smp_store_release() pairs with smp_load_aquire() in
+ * hns3_nic_reclaim_desc(). Ensure that the BD valid bit is updated.
+ */
+ smp_store_release(&ring->last_to_use, ring->next_to_use);
+
if (ring->tqp->mem_base)
hns3_tx_mem_doorbell(ring);
else
@@ -2121,7 +2130,6 @@ static void hns3_tx_doorbell(struct hns3_enet_ring *ring, int num,
ring->tqp->io_base + HNS3_RING_TX_RING_TAIL_REG);
ring->pending_buf = 0;
- WRITE_ONCE(ring->last_to_use, ring->next_to_use);
}
static void hns3_tsyn(struct net_device *netdev, struct sk_buff *skb,
@@ -3562,9 +3570,8 @@ static void hns3_reuse_buffer(struct hns3_enet_ring *ring, int i)
static bool hns3_nic_reclaim_desc(struct hns3_enet_ring *ring,
int *bytes, int *pkts, int budget)
{
- /* pair with ring->last_to_use update in hns3_tx_doorbell(),
- * smp_store_release() is not used in hns3_tx_doorbell() because
- * the doorbell operation already have the needed barrier operation.
+ /* This smp_load_acquire() pairs with smp_store_release() in
+ * hns3_tx_doorbell().
*/
int ltu = smp_load_acquire(&ring->last_to_use);
int ntc = ring->next_to_clean;
--
2.40.1
