From: David Ahern <dsahern@gmail.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>
Subject: Re: [PATCH net-next] tcp: Check daddr_cache before use in tracepoint
Date: Mon, 16 Oct 2017 15:55:00 -0600 [thread overview]
Message-ID: <cfd6b39a-41a6-ccf6-80a7-07089a2d6fea@gmail.com> (raw)
In-Reply-To: <CAM_iQpUgWJwjaRYw3vX4t20foheOrebU3U2ACZqrAbTYqYc-5A@mail.gmail.com>
On 10/16/17 3:46 PM, Cong Wang wrote:
> Well, for NULL case, the entry->saddr_v6 will not be filled with
> your patch.
I think you meant daddr_v6 and yes it will not get filled in, but 0 is
better than a panic ;-)
>
> How about using sk->sk_v6_daddr?
>
That works, but then both addresses should come from sk and not np:
diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index 1ffab6d96e94..7989c2dcedf1 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -46,9 +46,9 @@ TRACE_EVENT(tcp_retransmit_skb,
if (np) {
pin6 = (struct in6_addr *)__entry->saddr_v6;
- *pin6 = np->saddr;
+ *pin6 = sk->sk_v6_rcv_saddr;
pin6 = (struct in6_addr *)__entry->daddr_v6;
- *pin6 = *(np->daddr_cache);
+ *pin6 = sk->sk_v6_daddr;
} else {
pin6 = (struct in6_addr *)__entry->saddr_v6;
ipv6_addr_set_v4mapped(inet->inet_saddr, pin6);
So np is just a trigger for IPv6 versus v4 mapped.
I do have a question about why ipv4 addresses are non-NULL:
$ perf script
swapper 0 [000] 25.025102: tcp:tcp_retransmit_skb:
sport=22 dport=48076 saddr=127.0.0.6 daddr=127.0.0.6
saddrv6=2001:db8:1::4 daddrv6=2001:db8:1::64
swapper 0 [000] 25.231125: tcp:tcp_retransmit_skb:
sport=22 dport=48076 saddr=127.0.0.6 daddr=127.0.0.6
saddrv6=2001:db8:1::4 daddrv6=2001:db8:1::64
next prev parent reply other threads:[~2017-10-16 21:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-16 21:29 [PATCH net-next] tcp: Check daddr_cache before use in tracepoint David Ahern
2017-10-16 21:46 ` Cong Wang
2017-10-16 21:55 ` David Ahern [this message]
2017-10-16 22:05 ` Cong Wang
2017-10-16 22:08 ` David Ahern
2017-10-17 3:45 ` Eric Dumazet
2017-10-17 15:32 ` David Ahern
2017-10-17 17:05 ` Cong Wang
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