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From: John Fastabend <john.fastabend@gmail.com>
To: Jakub Sitnicki <jakub@cloudflare.com>, bpf@vger.kernel.org
Cc: netdev@vger.kernel.org, kernel-team@cloudflare.com,
	Eric Dumazet <edumazet@google.com>,
	John Fastabend <john.fastabend@gmail.com>,
	Lorenz Bauer <lmb@cloudflare.com>,
	Martin KaFai Lau <kafai@fb.com>
Subject: RE: [PATCH bpf-next v2 02/11] net, sk_msg: Annotate lockless access to sk_prot on clone
Date: Sat, 11 Jan 2020 15:14:46 -0800	[thread overview]
Message-ID: <5e1a56e630ee1_1e7f2b0c859c45c0c4@john-XPS-13-9370.notmuch> (raw)
In-Reply-To: <20200110105027.257877-3-jakub@cloudflare.com>

Jakub Sitnicki wrote:
> sk_msg and ULP frameworks override protocol callbacks pointer in
> sk->sk_prot, while TCP accesses it locklessly when cloning the listening
> socket.
> 
> Once we enable use of listening sockets with sockmap (and hence sk_msg),
> there can be shared access to sk->sk_prot if socket is getting cloned while
> being inserted/deleted to/from the sockmap from another CPU. Mark the
> shared access with READ_ONCE/WRITE_ONCE annotations.
> 
> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>

In sockmap side I fixed this by wrapping the access in a lock_sock[0]. So
Do you think this is still needed with that in mind? The bpf_clone call
is using sk_prot_creater and also setting the newsk's proto field. Even
if the listening parent sock was being deleted in parallel would that be
a problem? We don't touch sk_prot_creator from the tear down path. I've
only scanned the 3..11 patches so maybe the answer is below. If that is
the case probably an improved commit message would be helpful.

[0] https://patchwork.ozlabs.org/patch/1221536/

Thanks.

  reply	other threads:[~2020-01-11 23:14 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-10 10:50 [PATCH bpf-next v2 00/11] Extend SOCKMAP to store listening sockets Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 01/11] bpf, sk_msg: Don't reset saved sock proto on restore Jakub Sitnicki
2020-01-11 22:50   ` John Fastabend
2020-01-10 10:50 ` [PATCH bpf-next v2 02/11] net, sk_msg: Annotate lockless access to sk_prot on clone Jakub Sitnicki
2020-01-11 23:14   ` John Fastabend [this message]
2020-01-13 15:09     ` Jakub Sitnicki
2020-01-14  3:14       ` John Fastabend
2020-01-20 17:00       ` John Fastabend
2020-01-20 18:11         ` Jakub Sitnicki
2020-01-21 12:42           ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 03/11] net, sk_msg: Clear sk_user_data pointer on clone if tagged Jakub Sitnicki
2020-01-11 23:38   ` John Fastabend
2020-01-12 12:55   ` kbuild test robot
2020-01-13 20:15   ` Martin Lau
2020-01-14 16:04     ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 04/11] tcp_bpf: Don't let child socket inherit parent protocol ops on copy Jakub Sitnicki
2020-01-11  2:42   ` kbuild test robot
2020-01-11  3:02   ` kbuild test robot
2020-01-11 23:48   ` John Fastabend
2020-01-13 22:31     ` Jakub Sitnicki
2020-01-13 22:23   ` Martin Lau
2020-01-13 22:42     ` Jakub Sitnicki
2020-01-13 23:23       ` Martin Lau
2020-01-10 10:50 ` [PATCH bpf-next v2 05/11] bpf, sockmap: Allow inserting listening TCP sockets into sockmap Jakub Sitnicki
2020-01-11 23:59   ` John Fastabend
2020-01-13 15:48     ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 06/11] bpf, sockmap: Don't set up sockmap progs for listening sockets Jakub Sitnicki
2020-01-12  0:51   ` John Fastabend
2020-01-12  1:07     ` John Fastabend
2020-01-13 17:59       ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 07/11] bpf, sockmap: Return socket cookie on lookup from syscall Jakub Sitnicki
2020-01-12  0:56   ` John Fastabend
2020-01-13 23:12   ` Martin Lau
2020-01-14  3:16     ` John Fastabend
2020-01-14 15:48       ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 08/11] bpf, sockmap: Let all kernel-land lookup values in SOCKMAP Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 09/11] bpf: Allow selecting reuseport socket from a SOCKMAP Jakub Sitnicki
2020-01-12  1:00   ` John Fastabend
2020-01-13 23:45   ` Martin Lau
2020-01-15 12:41     ` Jakub Sitnicki
2020-01-13 23:51   ` Martin Lau
2020-01-15 12:57     ` Jakub Sitnicki
2020-01-10 10:50 ` [PATCH bpf-next v2 10/11] selftests/bpf: Extend SK_REUSEPORT tests to cover SOCKMAP Jakub Sitnicki
2020-01-12  1:01   ` John Fastabend
2020-01-10 10:50 ` [PATCH bpf-next v2 11/11] selftests/bpf: Tests for SOCKMAP holding listening sockets Jakub Sitnicki
2020-01-12  1:06   ` John Fastabend
2020-01-13 15:58     ` Jakub Sitnicki
2020-01-11  0:18 ` [PATCH bpf-next v2 00/11] Extend SOCKMAP to store " Alexei Starovoitov
2020-01-11 22:47 ` John Fastabend

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