Commit 61a1deac authored by Jian Shen's avatar Jian Shen Committed by Paolo Abeni
Browse files

net: hns3: fix tx timeout issue 



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: 20d06ca2 ("net: hns3: optimize the tx clean process")
Signed-off-by: default avatarJian Shen <shenjian15@huawei.com>
Signed-off-by: default avatarJijie Shao <shaojijie@huawei.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 08c6d8ba

drivers/net/ethernet/hisilicon/hns3/hns3_enet.c

+12 −5
Original line number Diff line number Diff line
@@ -2103,8 +2103,12 @@ 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;

	}
@@ -2115,6 +2119,11 @@ 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
@@ -2122,7 +2131,6 @@ 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,
@@ -3563,9 +3571,8 @@ 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;