linux-kernel - Re: [PATCH] Net:cache didn't flush when ipv6 rule changed

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Date: Wed, 28 Feb 2024 07:28:35 +0000
From: Lena Wang (王娜) <Lena.Wang@...iatek.com>
To: "davem@...emloft.net" <davem@...emloft.net>, "kuba@...nel.org"
	<kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>,
	"dsahern@...nel.org" <dsahern@...nel.org>, "edumazet@...gle.com"
	<edumazet@...gle.com>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Shiming Cheng (成诗明) <Shiming.Cheng@...iatek.com>
Subject: Re: [PATCH] Net:cache didn't flush when ipv6 rule changed

On Tue, 2024-02-27 at 08:06 -0700, David Ahern wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  On 2/26/24 6:11 AM, Lena Wang (王娜) wrote:
> 
> > diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
> > index 7523c4baef35..bec2cf4436e1 100644
> > --- a/net/ipv6/fib6_rules.c
> > +++ b/net/ipv6/fib6_rules.c
> > @@ -449,6 +449,15 @@ static size_t fib6_rule_nlmsg_payload(struct
> > fib_rule *rule)
> >                + nla_total_size(16); /* src */
> >  }
> > 
> > +static void fib6_rule_flush_cache(struct fib_rules_ops *ops)
> > +{
> > +       struct net *net = ops->fro_net;
> > +       if (!net)
> > +               return;
> > +       rt_genid_bump_ipv6(net);
> > +       return;
> > +}
> 
> This can be written as a 1-liner - the same way as the IPv4 flush
> cache:
> 
> static void fib6_rule_flush_cache(struct fib_rules_ops *ops)
> {
> rt_genid_bump_ipv6(ops->fro_net);
> }
> 
> 
> > +
> >  static const struct fib_rules_ops __net_initconst
> > fib6_rules_ops_template = {
> >         .family                 = AF_INET6,
> >         .rule_size              = sizeof(struct fib6_rule),
> > @@ -461,6 +470,7 @@ static const struct fib_rules_ops
> __net_initconst
> > fib6_rules_ops_template = {
> >         .compare                = fib6_rule_compare,
> >         .fill                   = fib6_rule_fill,
> >         .nlmsg_payload          = fib6_rule_nlmsg_payload,
> > +       .flush_cache    = fib6_rule_flush_cache,
> 
> this should be tabs and the columns should align with existing code.
> 
> 
> 
> >         .nlgroup                = RTNLGRP_IPV6_RULE,
> >         .owner                  = THIS_MODULE,
> >         .fro_net                = &init_net,
> > --
> > 2.18.0
> 

Dear David,
Update the patch as below, thanks.


From db01a40e45f51d00cb19e45a41507c97363d6ed8 Mon Sep 17 00:00:00 2001
From: shiming cheng <shiming.cheng@...iatek.com>
Date: Mon, 26 Feb 2024 20:17:58 +0800
Subject: [PATCH] Net:cache didn't flush when ipv6 rule changed

When changed from old rule&route configure to new one as below,
ipv6 cache dst_entry did not change to new route table as no
cache flush callback function, then forward to wrong out interface.
When fib6_check dst_entry, the fib6_node version[fn_sernm] is
always the same with socket dst_cookie, old cache dst_entry is
always used and no chance to update.

So we need to update fib6_node version when rule changed and
flush cache to avoid dispatching a wrong interface.

Signed-off-by: shiming cheng <shiming.cheng@...iatek.com>
---
 net/ipv6/fib6_rules.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
index 7523c4baef35..31d6183221a2 100644
--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -449,6 +449,11 @@ static size_t fib6_rule_nlmsg_payload(struct
fib_rule *rule)
               + nla_total_size(16); /* src */
 }

+static void fib6_rule_flush_cache(struct fib_rules_ops *ops)
+{
+       rt_genid_bump_ipv6(net);
+}
+
 static const struct fib_rules_ops __net_initconst
fib6_rules_ops_template = {
        .family                 = AF_INET6,
        .rule_size              = sizeof(struct fib6_rule),
@@ -461,6 +466,7 @@ static const struct fib_rules_ops __net_initconst
fib6_rules_ops_template = {
        .compare                = fib6_rule_compare,
        .fill                   = fib6_rule_fill,
        .nlmsg_payload          = fib6_rule_nlmsg_payload,
+       .flush_cache            = fib6_rule_flush_cache,
        .nlgroup                = RTNLGRP_IPV6_RULE,
        .owner                  = THIS_MODULE,
        .fro_net                = &init_net,
--
2.18.0