2018-09-26 10:29:48

by Yue Haibing

[permalink] [raw]
Subject: [PATCH net-next] hv_netvsc: fix return type of ndo_start_xmit function

The method ndo_start_xmit() is defined as returning an 'netdev_tx_t',
which is a typedef for an enum type, so make sure the implementation in
this driver has returns 'netdev_tx_t' value, and change the function
return type to netdev_tx_t.

As suggestion from Haiyang Zhang <[email protected]>, if netvsc_vf_xmit
fails, We are not sure if the error can go away after retrying, returning
NETDEV_TX_BUSY may cause infinite retry from the upper layer.
so just return NETDEV_TX_OK at there.

Found by coccinelle.

Signed-off-by: YueHaibing <[email protected]>
---
drivers/net/hyperv/netvsc_drv.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index ec69974..a1d44b4 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -511,7 +511,8 @@ static int netvsc_vf_xmit(struct net_device *net, struct net_device *vf_netdev,
return rc;
}

-static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
+static netdev_tx_t
+netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
{
struct net_device_context *net_device_ctx = netdev_priv(net);
struct hv_netvsc_packet *packet = NULL;
@@ -528,8 +529,10 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
*/
vf_netdev = rcu_dereference_bh(net_device_ctx->vf_netdev);
if (vf_netdev && netif_running(vf_netdev) &&
- !netpoll_tx_running(net))
- return netvsc_vf_xmit(net, vf_netdev, skb);
+ !netpoll_tx_running(net)) {
+ netvsc_vf_xmit(net, vf_netdev, skb);
+ return NETDEV_TX_OK;
+ }

/* We will atmost need two pages to describe the rndis
* header. We can only transmit MAX_PAGE_BUFFER_COUNT number
--
1.8.3.1




2018-09-26 12:00:39

by Stephen Hemminger

[permalink] [raw]
Subject: Re: [PATCH net-next] hv_netvsc: fix return type of ndo_start_xmit function

On Wed, 26 Sep 2018 18:25:10 +0800
YueHaibing <[email protected]> wrote:

> The method ndo_start_xmit() is defined as returning an 'netdev_tx_t',
> which is a typedef for an enum type, so make sure the implementation in
> this driver has returns 'netdev_tx_t' value, and change the function
> return type to netdev_tx_t.
>
> As suggestion from Haiyang Zhang <[email protected]>, if netvsc_vf_xmit
> fails, We are not sure if the error can go away after retrying, returning
> NETDEV_TX_BUSY may cause infinite retry from the upper layer.
> so just return NETDEV_TX_OK at there.
>
> Found by coccinelle.
>
> Signed-off-by: YueHaibing <[email protected]>
> ---
> drivers/net/hyperv/netvsc_drv.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
> index ec69974..a1d44b4 100644
> --- a/drivers/net/hyperv/netvsc_drv.c
> +++ b/drivers/net/hyperv/netvsc_drv.c
> @@ -511,7 +511,8 @@ static int netvsc_vf_xmit(struct net_device *net, struct net_device *vf_netdev,
> return rc;
> }
>
> -static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
> +static netdev_tx_t
> +netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
> {
> struct net_device_context *net_device_ctx = netdev_priv(net);
> struct hv_netvsc_packet *packet = NULL;
> @@ -528,8 +529,10 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
> */
> vf_netdev = rcu_dereference_bh(net_device_ctx->vf_netdev);
> if (vf_netdev && netif_running(vf_netdev) &&
> - !netpoll_tx_running(net))
> - return netvsc_vf_xmit(net, vf_netdev, skb);
> + !netpoll_tx_running(net)) {
> + netvsc_vf_xmit(net, vf_netdev, skb);
> + return NETDEV_TX_OK;
> + }
>
> /* We will atmost need two pages to describe the rndis
> * header. We can only transmit MAX_PAGE_BUFFER_COUNT number

Your patch loses the possible return values of netvsc_vf_xmit.
A suggested better fix would be to make netvsc_vf_xmit return netdev_tx_t type.
And this means the return value of dev_queue_xmit needs to be netdev_tx_t.

Please don't merge this as is.