[PATCH V2 for-next 1/8] net: hns: fix port unavailable after hnae_reserve_buffer_map fail

[Salil Mehta]

From: lipeng <lipeng...@huawei.com>

When hnae_reserve_buffer_map fail, it will break cycle and some
buffer description has no available memory, therefore the port will
be unavailable.

Signed-off-by: Peng Li <lipeng...@huawei.com>
Reviewed-by: Yisen Zhuang <yisen.zhu...@huawei.com>
Signed-off-by: Salil Mehta <salil.me...@huawei.com>
---
 drivers/net/ethernet/hisilicon/hns/hns_enet.c |   23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/hisilicon/hns/hns_enet.c 
b/drivers/net/ethernet/hisilicon/hns/hns_enet.c
index d7e1f8c..32ff270 100644
--- a/drivers/net/ethernet/hisilicon/hns/hns_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns/hns_enet.c
@@ -747,6 +747,14 @@ static void hns_nic_rx_up_pro(struct hns_nic_ring_data 
*ring_data,
        ndev->last_rx = jiffies;
 }
 
+static int hns_desc_unused(struct hnae_ring *ring)
+{
+       int ntc = ring->next_to_clean;
+       int ntu = ring->next_to_use;
+
+       return ((ntc >= ntu) ? 0 : ring->desc_num) + ntc - ntu;
+}
+
 static int hns_nic_rx_poll_one(struct hns_nic_ring_data *ring_data,
                               int budget, void *v)
 {
@@ -755,17 +763,21 @@ static int hns_nic_rx_poll_one(struct hns_nic_ring_data 
*ring_data,
        int num, bnum, ex_num;
 #define RCB_NOF_ALLOC_RX_BUFF_ONCE 16
        int recv_pkts, recv_bds, clean_count, err;
+       int unused_count = hns_desc_unused(ring);
 
        num = readl_relaxed(ring->io_base + RCB_REG_FBDNUM);
        rmb(); /* make sure num taken effect before the other data is touched */
 
        recv_pkts = 0, recv_bds = 0, clean_count = 0;
+       num -= unused_count;
 recv:
        while (recv_pkts < budget && recv_bds < num) {
                /* reuse or realloc buffers */
-               if (clean_count >= RCB_NOF_ALLOC_RX_BUFF_ONCE) {
-                       hns_nic_alloc_rx_buffers(ring_data, clean_count);
+               if (clean_count + unused_count >= RCB_NOF_ALLOC_RX_BUFF_ONCE) {
+                       hns_nic_alloc_rx_buffers(ring_data,
+                                                clean_count + unused_count);
                        clean_count = 0;
+                       unused_count = hns_desc_unused(ring);
                }
 
                /* poll one pkt */
@@ -789,7 +801,7 @@ recv:
        /* make all data has been write before submit */
        if (recv_pkts < budget) {
                ex_num = readl_relaxed(ring->io_base + RCB_REG_FBDNUM);
-
+               ex_num -= unused_count;
                if (ex_num > clean_count) {
                        num += ex_num - clean_count;
                        rmb(); /*complete read rx ring bd number*/
@@ -799,8 +811,9 @@ recv:
 
 out:
        /* make all data has been write before submit */
-       if (clean_count > 0)
-               hns_nic_alloc_rx_buffers(ring_data, clean_count);
+       if (clean_count + unused_count > 0)
+               hns_nic_alloc_rx_buffers(ring_data,
+                                        clean_count + unused_count);
 
        return recv_pkts;
 }
-- 
1.7.9.5