Re: [PATCH 2/2] app/testpmd: fix incorrect MTU verification

[Singh, Aman Deep]

On 4/6/2022 2:15 PM, Min Hu (Connor) wrote:
From: Huisong Li <lihuis...@huawei.com>

The macro RTE_ETHER_MIN_LEN isn't the minimum value of MTU. But testpmd
used it when execute 'port config mtu 0 xx' cmd. This patch fix it.

Fixes: 1bb4a528c41f ("ethdev: fix max Rx packet length")
Cc: sta...@dpdk.org

Signed-off-by: Huisong Li <lihuis...@huawei.com>
Signed-off-by: Min Hu (Connor) <humi...@huawei.com>
---
  app/test-pmd/cmdline.c |  4 ---
  app/test-pmd/config.c  | 55 ++++++++++++++++++++++++++++++++++++++++++
  2 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/app/test-pmd/cmdline.c b/app/test-pmd/cmdline.c
index 6ffea8e21a..91e4090582 100644
--- a/app/test-pmd/cmdline.c
+++ b/app/test-pmd/cmdline.c
@@ -2050,10 +2050,6 @@ cmd_config_mtu_parsed(void *parsed_result,
  {
        struct cmd_config_mtu_result *res = parsed_result;
  
-	if (res->value < RTE_ETHER_MIN_LEN) {
-               fprintf(stderr, "mtu cannot be less than %d\n", 
RTE_ETHER_MIN_LEN);
-               return;
-       }
        port_mtu_set(res->port_id, res->value);
  }
  
diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c
index bd689f9f86..1b1e738f83 100644
--- a/app/test-pmd/config.c
+++ b/app/test-pmd/config.c
@@ -1254,6 +1254,57 @@ port_reg_set(portid_t port_id, uint32_t reg_off, 
uint32_t reg_v)
        display_port_reg_value(port_id, reg_off, reg_v);
  }
  
+static uint32_t
+eth_dev_get_overhead_len(uint32_t max_rx_pktlen, uint16_t max_mtu)
+{
+       uint32_t overhead_len;
+
+       if (max_mtu != UINT16_MAX && max_rx_pktlen > max_mtu)
+               overhead_len = max_rx_pktlen - max_mtu;
+       else
+               overhead_len = RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN;
+
+       return overhead_len;
+}
+
+static int
+eth_dev_validate_mtu(uint16_t port_id, uint16_t mtu)
+{
+       struct rte_eth_dev_info dev_info;
+       uint32_t overhead_len;
+       uint32_t frame_size;
+       int ret;
+
+       ret = rte_eth_dev_info_get(port_id, &dev_info);
+       if (ret != 0)
+               return ret;
+
+       if (mtu < dev_info.min_mtu) {
+               fprintf(stderr,
+                       "MTU (%u) < device min MTU (%u) for port_id %u\n",
+                       mtu, dev_info.min_mtu, port_id);
+               return -EINVAL;
+       }
+       if (mtu > dev_info.max_mtu) {
+               fprintf(stderr,
+                       "MTU (%u) > device max MTU (%u) for port_id %u\n",
+                       mtu, dev_info.max_mtu, port_id);
+               return -EINVAL;
+       }
+
+       overhead_len = eth_dev_get_overhead_len(dev_info.max_rx_pktlen,
+                       dev_info.max_mtu);
+       frame_size = mtu + overhead_len;
+       if (frame_size > dev_info.max_rx_pktlen) {
+               fprintf(stderr,
+                       "Frame size (%u) > device max frame size (%u) for port_id 
%u\n",
+                       frame_size, dev_info.max_rx_pktlen, port_id);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
  void
  port_mtu_set(portid_t port_id, uint16_t mtu)
  {
@@ -1263,6 +1314,10 @@ port_mtu_set(portid_t port_id, uint16_t mtu)
        if (port_id_is_invalid(port_id, ENABLED_WARN))
                return;
  
+	diag = eth_dev_validate_mtu(port_id, mtu);
+       if (diag != 0)
+               return;
+
        if (port->need_reconfig == 0) {
                diag = rte_eth_dev_set_mtu(port_id, mtu);
                if (diag != 0) {
I just wanted to know if these added functions eth_dev_validate_mtu() &  
eth_dev_get_overhead_len()
are copy of ethdev library API's in file "rte_ethdev.c", which get 
called by rte_eth_dev_set_mtu.
Is our intent, is to call these twice ?