Re: [PATCH] arp: Remove the arp_hh_ops structure

From: Eric Dumazet
Date: Mon Feb 22 2021 - 03:39:21 EST




On 2/22/21 4:15 AM, Yejune Deng wrote:
> The arp_hh_ops structure is similar to the arp_generic_ops structure.
> but the latter is more general,so remove the arp_hh_ops structure.
>
> Fix when took out the neigh->ops assignment:
> 8.973653] #PF: supervisor read access in kernel mode
> [ 8.975027] #PF: error_code(0x0000) - not-present page
> [ 8.976310] PGD 0 P4D 0
> [ 8.977036] Oops: 0000 [#1] SMP PTI
> [ 8.977973] CPU: 1 PID: 210 Comm: sd-resolve Not tainted 5.11.0-rc7-02046-g4591591ab715 #1
> [ 8.979998] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
> [ 8.981996] RIP: 0010:neigh_probe (kbuild/src/consumer/net/core/neighbour.c:1009)
>

I have a hard time understanding this patch submission.

This seems a mix of a net-next and net material ?



> Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>

If this is a bug fix, we want a Fixes: tag

This will really help us. Please don't let us guess what is going on.


Also, if this is not a bug fix, this should target net-next tree,
please take a look at Documentation/networking/netdev-FAQ.rst

In short, the stack trace in this changelog seems to be not
related to this patch, maybe a prior version ? We do not want
to keep artifacts of some buggy version that was never merged
into official tree.

Thanks.

> Signed-off-by: Yejune Deng <yejune.deng@xxxxxxxxx>
> ---
> net/ipv4/arp.c | 15 ++-------------
> 1 file changed, 2 insertions(+), 13 deletions(-)
>
> diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
> index 922dd73e5740..9ee59c2e419a 100644
> --- a/net/ipv4/arp.c
> +++ b/net/ipv4/arp.c
> @@ -135,14 +135,6 @@ static const struct neigh_ops arp_generic_ops = {
> .connected_output = neigh_connected_output,
> };
>
> -static const struct neigh_ops arp_hh_ops = {
> - .family = AF_INET,
> - .solicit = arp_solicit,
> - .error_report = arp_error_report,
> - .output = neigh_resolve_output,
> - .connected_output = neigh_resolve_output,
> -};
> -
> static const struct neigh_ops arp_direct_ops = {
> .family = AF_INET,
> .output = neigh_direct_output,
> @@ -277,12 +269,9 @@ static int arp_constructor(struct neighbour *neigh)
> memcpy(neigh->ha, dev->broadcast, dev->addr_len);
> }
>
> - if (dev->header_ops->cache)
> - neigh->ops = &arp_hh_ops;
> - else
> - neigh->ops = &arp_generic_ops;
> + neigh->ops = &arp_generic_ops;
>
> - if (neigh->nud_state & NUD_VALID)
> + if (!dev->header_ops->cache && (neigh->nud_state & NUD_VALID))
> neigh->output = neigh->ops->connected_output;
> else
> neigh->output = neigh->ops->output;
>