net: hns3: schedule the polling again when allocation fails

Currently when there is a rx page allocation failure, it is
possible that polling may be stopped if there is no more packet
to be reveiced, which may cause queue stall problem under memory
pressure.

This patch makes sure polling is scheduled again when there is
any rx page allocation failure, and polling will try to allocate
receive buffers until it succeeds.

Now the allocation retry is added, it is unnecessary to do the rx
page allocation at the end of rx cleaning, so remove it. And reset
the unused_count to zero after calling hns3_nic_alloc_rx_buffers()
to avoid calling hns3_nic_alloc_rx_buffers() repeatedly under
memory pressure.

Fixes: 76ad4f0ee747 ("net: hns3: Add support of HNS3 Ethernet Driver for hip08 SoC")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
index 2ecc9ab..4b886a1 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
@@ -3486,7 +3486,8 @@
 	return ((ntc >= ntu) ? 0 : ring->desc_num) + ntc - ntu;
 }
 
-static void hns3_nic_alloc_rx_buffers(struct hns3_enet_ring *ring,
+/* Return true if there is any allocation failure */
+static bool hns3_nic_alloc_rx_buffers(struct hns3_enet_ring *ring,
 				      int cleand_count)
 {
 	struct hns3_desc_cb *desc_cb;
@@ -3511,7 +3512,10 @@
 				hns3_rl_err(ring_to_netdev(ring),
 					    "alloc rx buffer failed: %d\n",
 					    ret);
-				break;
+
+				writel(i, ring->tqp->io_base +
+				       HNS3_RING_RX_RING_HEAD_REG);
+				return true;
 			}
 			hns3_replace_buffer(ring, ring->next_to_use, &res_cbs);
 
@@ -3524,6 +3528,7 @@
 	}
 
 	writel(i, ring->tqp->io_base + HNS3_RING_RX_RING_HEAD_REG);
+	return false;
 }
 
 static bool hns3_can_reuse_page(struct hns3_desc_cb *cb)
@@ -4175,6 +4180,7 @@
 {
 #define RCB_NOF_ALLOC_RX_BUFF_ONCE 16
 	int unused_count = hns3_desc_unused(ring);
+	bool failure = false;
 	int recv_pkts = 0;
 	int err;
 
@@ -4183,9 +4189,9 @@
 	while (recv_pkts < budget) {
 		/* Reuse or realloc buffers */
 		if (unused_count >= RCB_NOF_ALLOC_RX_BUFF_ONCE) {
-			hns3_nic_alloc_rx_buffers(ring, unused_count);
-			unused_count = hns3_desc_unused(ring) -
-					ring->pending_buf;
+			failure = failure ||
+				hns3_nic_alloc_rx_buffers(ring, unused_count);
+			unused_count = 0;
 		}
 
 		/* Poll one pkt */
@@ -4204,11 +4210,7 @@
 	}
 
 out:
-	/* Make all data has been write before submit */
-	if (unused_count > 0)
-		hns3_nic_alloc_rx_buffers(ring, unused_count);
-
-	return recv_pkts;
+	return failure ? budget : recv_pkts;
 }
 
 static void hns3_update_rx_int_coalesce(struct hns3_enet_tqp_vector *tqp_vector)