On 3/5/2021 10:22 AM, Lijun Ou wrote:
From: Huisong Li <lihuis...@huawei.com>

The "fwd_config_setup()" function does release and apply for
memory of forwarding flows, and re-establish these streams when
rxq/txq or rxd/txd is changed. The function is also called by
"start_packet_forwarding()" when user executes "start" cmd.
All changes for rxq/txq or rxd/txd can be updated uniformly
when this command is executed. Therefore, it is a little
redundant in the "cmd_config_rx_tx_parsed" function.

In addition, the forwarding stream under one TC is configured
based on number of queues allocated to TC. And number of queues
allocated to TC is updated after calling  "rte_eth_dev_configure"
again. If the number of queues is reduced after configuring the
DCB, and then, release and apply for stream memory, and reinitialize
the forwarding stream under the DCB mode based on the old TC
information. As a result, null pointer may be accessed.

Like:
set nbcore 4
port stop all
port config 0 dcb vt off 4 pfc on
port start all
port stop all
port config all rxq 8
port config all txq 8

At the moment, a segmentation fault occurs.


Hi Lijun, Xiaoyun,

I read the thread and checked the code, but still I am not completely clear with the dcp implementation in testpmd.

But the "dcb_config = 0" in the 'stop_port()' that has been removed in the patch 1/3 seems preventing these kind of config combination, with implicitly resetting the dcb feature with port stop.

What do you think just have the number of forwarding cores adjustment change in the patch 1/3, and keep the 'stop_port()' as it is, will it solve this problem, and how acceptable it will be do you think?

Fixes: ce8d561418d4 ("app/testpmd: add port configuration settings")
Cc: sta...@dpdk.org

Signed-off-by: Huisong Li <lihuis...@huawei.com>
Signed-off-by: Lijun Ou <ouli...@huawei.com>
---
V1->V2:
- use stream instead of flow
---
  app/test-pmd/cmdline.c | 2 --
  1 file changed, 2 deletions(-)

diff --git a/app/test-pmd/cmdline.c b/app/test-pmd/cmdline.c
index 4df0c32..e316f5c 100644
--- a/app/test-pmd/cmdline.c
+++ b/app/test-pmd/cmdline.c
@@ -1837,8 +1837,6 @@ cmd_config_rx_tx_parsed(void *parsed_result,
                return;
        }
- fwd_config_setup();
-
        init_port_config();
cmd_reconfig_device_queue(RTE_PORT_ALL, 1, 1);


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