Re: [PATCHv3 for-next 1/1] RDMA/rxe: Disable ipv6 features when ipv6.disable set in cmdline

[Jason Gunthorpe <jgg@nvidia.com>]

On Thu, Mar 25, 2021 at 09:27:23PM -0400, Zhu Yanjun wrote:
> From: Zhu Yanjun <zyjzyj2000@gmail.com>
> 
> When ipv6.disable=1 is set in cmdline, ipv6 is actually disabled
> in the stack. As such, the operations of ipv6 in RXE will fail.
> So ipv6 features in RXE should also be disabled in RXE.
> 
> Fixes: 8700e3e7c4857 ("Soft RoCE driver")
> Reported-by: Yi Zhang <yi.zhang@redhat.com>
> Signed-off-by: Zhu Yanjun <zyjzyj2000@gmail.com>
> Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
> Tested-by: Yi Zhang <yi.zhang@redhat.com>
> V2->V3: Remove print message
> V1->V2: Modify the pr_info messages
>  drivers/infiniband/sw/rxe/rxe_net.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/infiniband/sw/rxe/rxe_net.c b/drivers/infiniband/sw/rxe/rxe_net.c
> index 01662727dca0..3b8ed007e8af 100644
> +++ b/drivers/infiniband/sw/rxe/rxe_net.c
> @@ -72,6 +72,9 @@ static struct dst_entry *rxe_find_route6(struct net_device *ndev,
>  	struct dst_entry *ndst;
>  	struct flowi6 fl6 = { { 0 } };
>  
> +	if (!ipv6_mod_enabled())
> +		return NULL;
> +
>  	memset(&fl6, 0, sizeof(fl6));
>  	fl6.flowi6_oif = ndev->ifindex;
>  	memcpy(&fl6.saddr, saddr, sizeof(*saddr));

What is this actually fixing?

ndst = ipv6_stub->ipv6_dst_lookup_flow() will return an error if the
ipv6 support is not loaded so why do we need more tests?

> @@ -616,6 +619,8 @@ static int rxe_net_ipv4_init(void)
>  static int rxe_net_ipv6_init(void)
>  {
>  #if IS_ENABLED(CONFIG_IPV6)
> +	if (!ipv6_mod_enabled())
> +		return 0;
>  
>  	recv_sockets.sk6 = rxe_setup_udp_tunnel(&init_net,
>  						htons(ROCE_V2_UDP_DPORT), true);

rxe_setup_udp_tunnel() should already fail naturally because the V6
socket won't be created

What is the actual symptom this patch is trying to address?

Jason