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[195.231.47.232]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c29660d49b5sm562688066b.46.2026.09.15.02.20.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 15 Sep 2026 02:20:16 -0700 (PDT) Message-ID: Date: Tue, 15 Sep 2026 11:20:15 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net v5 1/1] ip6_tunnel: snapshot encap in xmit To: Ren Wei , netdev@vger.kernel.org Cc: dsahern@kernel.org, idosch@nvidia.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, horms@kernel.org, tom@herbertland.com, vega@nebusec.ai, petalzu987@gmail.com References: Content-Language: en-US From: Paolo Abeni In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/9/26 9:01 PM, Ren Wei wrote: > diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h > index 7c9aadfe8fe3..ab217ddbeb20 100644 > --- a/include/net/ip_tunnels.h > +++ b/include/net/ip_tunnels.h > @@ -522,6 +522,16 @@ skb_vlan_inet_prepare(struct sk_buff *skb, bool inner_proto_inherit) > return SKB_NOT_DROPPED_YET; > } > > +static inline void > +ip_tunnel_encap_snapshot(struct ip_tunnel_encap *dst, > + const struct ip_tunnel_encap *src) > +{ > + dst->type = READ_ONCE(src->type); > + dst->flags = READ_ONCE(src->flags); > + dst->sport = READ_ONCE(src->sport); > + dst->dport = READ_ONCE(src->dport); The above can still race with ip6_tnl_encap_setup() giving inconsistent results. As noted by Eric in v4 the solution would be convering the encap to RCU. I think that the additional dereference would be actually faster than the extra memory copy. /P