[PATCH] net/kni: reset rte_kni_conf struct before initialization

[PATCH] net/kni: reset rte_kni_conf struct before initialization

[Harold Huang]

When kni driver calls eth_kni_start to start device, some fields such
as min_mtu and max_mtu of rte_kni_conf are not initialized. It will
cause kni_ioctl_create create a kni netdevice with a random min_mtu
and max_mtu value. This is unexpected and in some time we could not
change the kni device mtu with ip link command.

Fixes: ff1e35fb5f8 ("kni: calculate MTU from mbuf size")
Signed-off-by: Harold Huang <baymaxhuang@gmail.com>
---
 drivers/net/kni/rte_eth_kni.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/kni/rte_eth_kni.c b/drivers/net/kni/rte_eth_kni.c
index c428caf441..23b15edfac 100644
--- a/drivers/net/kni/rte_eth_kni.c
+++ b/drivers/net/kni/rte_eth_kni.c
@@ -128,6 +128,7 @@ eth_kni_start(struct rte_eth_dev *dev)
  const char *name = dev->device->name + 4; /* remove net_ */

  mb_pool = internals->rx_queues[0].mb_pool;
+ memset(&conf, 0, sizeof(conf));
  strlcpy(conf.name, name, RTE_KNI_NAMESIZE);
  conf.force_bind = 0;
  conf.group_id = port_id;
--
2.18.2

[PATCH v4] net/kni: reset rte_kni_conf struct before initialization

[Harold Huang]

When kni driver calls eth_kni_start to start device, some fields such as
min_mtu and max_mtu of rte_kni_conf are not initialized. It will cause
kni_ioctl_create create a kni netdevice with a random min_mtu and max_mtu
value. This isunexpected and in some time we could not change the kni
device mtu with ip link command.

Fixes: ff1e35fb5f8 ("kni: calculate MTU from mbuf size")
Signed-off-by: Harold Huang <baymaxhuang@gmail.com>
---
 drivers/net/kni/rte_eth_kni.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/kni/rte_eth_kni.c b/drivers/net/kni/rte_eth_kni.c
index c428caf441..23b15edfac 100644
--- a/drivers/net/kni/rte_eth_kni.c
+++ b/drivers/net/kni/rte_eth_kni.c
@@ -128,6 +128,7 @@ eth_kni_start(struct rte_eth_dev *dev)
 	const char *name = dev->device->name + 4; /* remove net_ */
 
 	mb_pool = internals->rx_queues[0].mb_pool;
+	memset(&conf, 0, sizeof(conf));
 	strlcpy(conf.name, name, RTE_KNI_NAMESIZE);
 	conf.force_bind = 0;
 	conf.group_id = port_id;
-- 
2.27.0

Re: [PATCH v4] net/kni: reset rte_kni_conf struct before initialization

[Thomas Monjalon]

+Cc Ferruh

05/12/2021 07:21, Harold Huang:
> When kni driver calls eth_kni_start to start device, some fields such as
> min_mtu and max_mtu of rte_kni_conf are not initialized. It will cause
> kni_ioctl_create create a kni netdevice with a random min_mtu and max_mtu
> value. This isunexpected and in some time we could not change the kni
> device mtu with ip link command.
> 
> Fixes: ff1e35fb5f8 ("kni: calculate MTU from mbuf size")
> Signed-off-by: Harold Huang <baymaxhuang@gmail.com>
> ---
>  drivers/net/kni/rte_eth_kni.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/kni/rte_eth_kni.c b/drivers/net/kni/rte_eth_kni.c
> index c428caf441..23b15edfac 100644
> --- a/drivers/net/kni/rte_eth_kni.c
> +++ b/drivers/net/kni/rte_eth_kni.c
> @@ -128,6 +128,7 @@ eth_kni_start(struct rte_eth_dev *dev)
>  	const char *name = dev->device->name + 4; /* remove net_ */
>  
>  	mb_pool = internals->rx_queues[0].mb_pool;
> +	memset(&conf, 0, sizeof(conf));
>  	strlcpy(conf.name, name, RTE_KNI_NAMESIZE);
>  	conf.force_bind = 0;
>  	conf.group_id = port_id;

Re: [PATCH v4] net/kni: reset rte_kni_conf struct before initialization

[Harold Huang]

The problem this patch wants to solve can be reproduced by ovs-dpdk:

1. create a kni  port in ovs:
ovs-vsctl add-port ovs-br0 kni0 -- set Interface kni0 type=dpdk
options:dpdk-devargs=net_kni0

2. change the mtu of the kni device in kernel:
ip link set kni0  mtu 1500

If we do not set rte_kni_conf to 0, the min_mtu and max_mtu are random
and change mtu could be failed.