Messages in this thread | | | Date | Wed, 12 Jan 2022 16:49:12 +0000 | Subject | Re: [PATCH 09/14] ipv6: hand dst refs to cork setup | From | Pavel Begunkov <> |
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On 1/12/22 11:15, Paolo Abeni wrote: > 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.
perfect, thanks
>> @@ -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() -- Pavel Begunkov
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