Messages in this thread Patch in this message | | | Subject | Re: [PATCH 09/14] ipv6: hand dst refs to cork setup | From | Paolo Abeni <> | Date | Wed, 12 Jan 2022 12:15:01 +0100 |
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On Tue, 2022-01-11 at 20:39 +0000, Pavel Begunkov wrote: > On 1/11/22 17:11, Paolo Abeni wrote: > > On Tue, 2022-01-11 at 01:21 +0000, Pavel Begunkov wrote: > > > During cork->dst setup, ip6_make_skb() gets an additional reference to > > > a passed in dst. However, udpv6_sendmsg() doesn't need dst after calling > > > ip6_make_skb(), and so we can save two additional atomics by passing > > > dst references to ip6_make_skb(). udpv6_sendmsg() is the only caller, so > > > it's enough to make sure it doesn't use dst afterwards. > > > > What about the corked path in udp6_sendmsg()? I mean: > > It doesn't change it for callers, so the ref stays with udp6_sendmsg() when > corking. To compensate for ip6_setup_cork() there is an explicit dst_hold() > in ip6_append_data, should be fine.
Whoops, I underlooked that chunk, thanks for pointing it out!
Yes, it looks fine.
> @@ -1784,6 +1784,7 @@ int ip6_append_data(struct sock *sk, > /* > * setup for corking > */ > + dst_hold(&rt->dst); > err = ip6_setup_cork(sk, &inet->cork, &np->cork, > ipc6, rt); > > > I don't care much about corking perf, but might be better to implement > this "handing away" for ip6_append_data() as well to be more consistent > with ip6_make_skb().
I'm personally fine with the the added dst_hold() in ip6_append_data()
Thanks!
Paolo
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