Re: [PATCH] net: gain ipv4 mtu when mtu is not locked

[David Miller]

From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Date: Mon, 24 Aug 2020 07:35:28 -0400

> When mtu is locked, we should not obtain ipv4 mtu as we return immediately
> in this case and leave acquired ipv4 mtu unused.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
> ---
>  net/ipv4/route.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> index 8ca6bcab7b03..f0a0faf58267 100644
> --- a/net/ipv4/route.c
> +++ b/net/ipv4/route.c
> @@ -1013,13 +1013,14 @@ out:	kfree_skb(skb);
>  static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
>  {
>  	struct dst_entry *dst = &rt->dst;
> -	u32 old_mtu = ipv4_mtu(dst);
> +	u32 old_mtu;
>  	struct fib_result res;
>  	bool lock = false;

Please preserve the reverse christmas tree ordering of local variables here.