Subject: Re: [PATCH v3 ipsec-next 3/3] xfrm: wrap xfrmdev_ops with offload config

From: Marcelo Ricardo Leitner <[email-masked]>
Date: Wed, 20 Dec 2017 14:03:01 -0200

On Tue, Dec 19, 2017 at 03:35:49PM -0800, Shannon Nelson wrote:
> There's no reason to define netdev->xfrmdev_ops if
> the offload facility is not CONFIG'd in.
> 
> Signed-off-by: Shannon Nelson <[email-masked]>

This one could use a Fixes tag perhaps:
Fixes: d77e38e612a0 ("xfrm: Add an IPsec hardware offloading API")

as in theory the build was broken since then, as it added:
+#ifdef CONFIG_XFRM_OFFLOAD
+struct xfrmdev_ops {
...
+#ifdef CONFIG_XFRM
+       const struct xfrmdev_ops *xfrmdev_ops;

So the pointer would have an undefined type
  if CONFIG_XFRM && !CONFIG_XFRM_OFFLOAD
Though I couldn't reproduce this, not sure why.

But.. is it buildable with this patch? I mine failed:

obj-$(CONFIG_XFRM) := xfrm_policy.o xfrm_state.o xfrm_hash.o \
                      xfrm_input.o xfrm_output.o \
                      xfrm_sysctl.o xfrm_replay.o xfrm_device.o

so xfrm_device is always in if CONFIG_XFRM is there,
xfrm_dev_init(), via xfrm_dev_notifier -> xfrm_dev_event() ->
  xfrm_dev_register() and then:

static int xfrm_dev_register(struct net_device *dev)
{
        if ((dev->features & NETIF_F_HW_ESP) && !dev->xfrmdev_ops)
                                                 ^^^^^^^^^^^^^^^^

We can't control CONFIG_XFRM_OFFLOAD directly, so unless you
unselected other offloadings such as INET_ESP_OFFLOAD, it is still on.

linux/net/xfrm/xfrm_device.c: In function ‘xfrm_dev_register’:
linux/net/xfrm/xfrm_device.c:147:48: error: ‘struct net_device’ has no member named ‘xfrmdev_ops’; did you mean ‘netdev_ops’?
  if ((dev->features & NETIF_F_HW_ESP) && !dev->xfrmdev_ops)
                                                ^~~~~~~~~~~
                                                netdev_ops

> ---
>  include/linux/netdevice.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 2eaac7d..145d0de 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -1697,7 +1697,7 @@ struct net_device {
>  	const struct ndisc_ops *ndisc_ops;
>  #endif
>  
> -#ifdef CONFIG_XFRM
> +#ifdef CONFIG_XFRM_OFFLOAD
>  	const struct xfrmdev_ops *xfrmdev_ops;
>  #endif
>  
> -- 
> 2.7.4
>