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Message-ID: <f9dadb5e-172a-4c39-c564-38be672ef0eb@stressinduktion.org> Date: Mon, 19 Dec 2016 17:36:46 +0100 From: Hannes Frederic Sowa <hannes@...essinduktion.org> To: Eric Dumazet <eric.dumazet@...il.com>, Julian Anastasov <ja@....bg> Cc: netdev@...r.kernel.org, linux-sctp@...r.kernel.org, YueHaibing <yuehaibing@...wei.com> Subject: Re: [PATCH RFC net-next 2/7] net: add dst_pending_confirm flag to skbuff On 19.12.2016 17:17, Eric Dumazet wrote: > On Sun, 2016-12-18 at 22:56 +0200, Julian Anastasov wrote: > >> >> +static inline void sock_confirm_neigh(struct sk_buff *skb, struct neighbour *n) >> +{ >> + if (unlikely(skb->dst_pending_confirm)) { >> + struct sock *sk = skb->sk; >> + unsigned long now = jiffies; >> + >> + /* avoid dirtying neighbour */ >> + if (n->confirmed != now) >> + n->confirmed = now; >> + if (sk && sk->sk_dst_pending_confirm) >> + sk->sk_dst_pending_confirm = 0; >> + } >> +} >> + > > I am still digesting this awesome patch series ;) > > Not sure why you used an unlikely() here. TCP for example would hit this > path quite often. > > So considering sk_dst_pending_confirm might be dirtied quite often, > > I am not sure why you placed it in the cache line that contains > sk_rx_dst (in 1st patch) Because they have to stay synchronized? If we modify sk_rx_dst, we automatically also must clear pending_confirm, otherwise we might end up confirming a wrong neighbor. Bye, Hannes
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