From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: therbert@google.com, alexander.h.duyck@intel.com, netdev@vger.kernel.org
Subject: Re: [PATCH v2 net-next] tcp: remove dst refcount false sharing for prequeue mode
Date: Mon, 08 Sep 2014 14:21:43 -0700 (PDT) [thread overview]
Message-ID: <20140908.142143.807176983873922125.davem@davemloft.net> (raw)
In-Reply-To: <1410188767.11872.110.camel@edumazet-glaptop2.roam.corp.google.com>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Mon, 08 Sep 2014 08:06:07 -0700
> @@ -1559,7 +1559,17 @@ bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
> skb_queue_len(&tp->ucopy.prequeue) == 0)
> return false;
>
> - skb_dst_force(skb);
> + /* Before escaping RCU protected region, we need to take care of skb
> + * dst. Prequeue is only enabled for established sockets.
> + * For such sockets, we might need the skb dst only to set sk->sk_rx_dst
> + * Instead of doing full sk_rx_dst validity here, let's perform
> + * an optimistic check.
> + */
> + if (likely(sk->sk_rx_dst))
> + skb_dst_drop(skb);
> + else
> + skb_dst_force(skb);
> +
This might not be a strong enough test.
We have to also make all of the checks that would cause the input
path to invalidate sk->sk_rx_dst too.
Otherwise, if it does, we'll crash when we try to do a dst_hold()
on skb_dst(skb) in sk->sk_rx_dst_set().
next prev parent reply other threads:[~2014-09-08 21:21 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-14 18:19 Performance regression on kernels 3.10 and newer Alexander Duyck
2014-08-14 18:46 ` Eric Dumazet
2014-08-14 19:50 ` Eric Dumazet
2014-08-14 19:59 ` Rick Jones
2014-08-14 20:31 ` Alexander Duyck
2014-08-14 20:51 ` Eric Dumazet
2014-08-14 20:46 ` Eric Dumazet
2014-08-14 23:16 ` Alexander Duyck
2014-08-14 23:20 ` David Miller
2014-08-14 23:25 ` Tom Herbert
2014-08-21 23:24 ` David Miller
2014-09-06 14:45 ` Eric Dumazet
2014-09-06 15:27 ` Eric Dumazet
2014-09-06 15:46 ` Eric Dumazet
2014-09-06 16:38 ` Eric Dumazet
2014-09-06 18:21 ` Eric Dumazet
2014-09-07 19:05 ` [PATCH net] ipv6: refresh rt6i_genid in ip6_pol_route() Eric Dumazet
2014-09-07 22:54 ` David Miller
2014-09-08 4:18 ` Eric Dumazet
2014-09-08 4:27 ` David Miller
2014-09-08 4:43 ` Eric Dumazet
2014-09-08 4:59 ` David Miller
2014-09-08 5:07 ` Eric Dumazet
2014-09-08 8:11 ` Nicolas Dichtel
2014-09-08 10:28 ` Eric Dumazet
2014-09-08 12:16 ` Nicolas Dichtel
2014-09-08 18:48 ` Vlad Yasevich
2014-09-09 12:58 ` Hannes Frederic Sowa
2014-09-10 9:31 ` [PATCH net-next] ipv6: implement rt_genid_bump_ipv6 with fn_sernum and remove rt6i_genid Hannes Frederic Sowa
2014-09-10 13:26 ` Vlad Yasevich
2014-09-10 13:42 ` Hannes Frederic Sowa
2014-09-10 20:09 ` David Miller
2014-09-11 8:30 ` Hannes Frederic Sowa
2014-09-11 12:22 ` Vlad Yasevich
2014-09-11 12:40 ` Hannes Frederic Sowa
2014-09-11 12:05 ` Hannes Frederic Sowa
2014-09-11 14:19 ` Vlad Yasevich
2014-09-11 14:32 ` Hannes Frederic Sowa
2014-09-11 14:44 ` Vlad Yasevich
2014-09-11 14:47 ` Hannes Frederic Sowa
2014-09-08 15:06 ` [PATCH v2 net-next] tcp: remove dst refcount false sharing for prequeue mode Eric Dumazet
2014-09-08 21:21 ` David Miller [this message]
2014-09-08 21:30 ` Eric Dumazet
2014-09-08 22:41 ` David Miller
2014-09-09 23:56 ` David Miller
2014-08-15 17:15 ` Performance regression on kernels 3.10 and newer Alexander Duyck
2014-08-15 17:59 ` Eric Dumazet
2014-08-15 18:49 ` Tom Herbert
2014-08-15 19:10 ` Alexander Duyck
2014-08-15 22:16 ` Tom Herbert
2014-08-15 23:23 ` Alexander Duyck
2014-08-18 9:03 ` David Laight
2014-08-18 15:22 ` Alexander Duyck
2014-08-18 15:29 ` Rick Jones
2014-08-21 23:51 ` David Miller
2014-08-14 23:48 ` Eric Dumazet
2014-08-15 0:33 ` Rick Jones
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20140908.142143.807176983873922125.davem@davemloft.net \
--to=davem@davemloft.net \
--cc=alexander.h.duyck@intel.com \
--cc=eric.dumazet@gmail.com \
--cc=netdev@vger.kernel.org \
--cc=therbert@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).