From: Jakub Sitnicki <jakub@cloudflare.com>
To: John Fastabend <john.fastabend@gmail.com>
Cc: cong.wang@bytedance.com, daniel@iogearbox.net, lmb@isovalent.com,
edumazet@google.com, bpf@vger.kernel.org, netdev@vger.kernel.org,
ast@kernel.org, andrii@kernel.org, will@isovalent.com
Subject: Re: [PATCH bpf v2 04/12] bpf: sockmap, handle fin correctly
Date: Mon, 03 Apr 2023 13:11:07 +0200 [thread overview]
Message-ID: <87a5zpdxu7.fsf@cloudflare.com> (raw)
In-Reply-To: <20230327175446.98151-5-john.fastabend@gmail.com>
On Mon, Mar 27, 2023 at 10:54 AM -07, John Fastabend wrote:
> The sockmap code is returning EAGAIN after a FIN packet is received and no
> more data is on the receive queue. Correct behavior is to return 0 to the
> user and the user can then close the socket. The EAGAIN causes many apps
> to retry which masks the problem. Eventually the socket is evicted from
> the sockmap because its released from sockmap sock free handling. The
> issue creates a delay and can cause some errors on application side.
>
> To fix this check on sk_msg_recvmsg side if length is zero and FIN flag
> is set then set return to zero. A selftest will be added to check this
> condition.
>
> Fixes: 04919bed948dc ("tcp: Introduce tcp_read_skb()")
> Tested-by: William Findlay <will@isovalent.com>
> Signed-off-by: John Fastabend <john.fastabend@gmail.com>
> ---
> net/ipv4/tcp_bpf.c | 31 +++++++++++++++++++++++++++++++
> 1 file changed, 31 insertions(+)
>
> diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
> index cf26d65ca389..3a0f43f3afd8 100644
> --- a/net/ipv4/tcp_bpf.c
> +++ b/net/ipv4/tcp_bpf.c
[...]
> @@ -193,6 +211,19 @@ static int tcp_bpf_recvmsg_parser(struct sock *sk,
> lock_sock(sk);
> msg_bytes_ready:
> copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
> + /* The typical case for EFAULT is the socket was gracefully
> + * shutdown with a FIN pkt. So check here the other case is
> + * some error on copy_page_to_iter which would be unexpected.
> + * On fin return correct return code to zero.
> + */
> + if (copied == -EFAULT) {
> + bool is_fin = is_next_msg_fin(psock);
> +
> + if (is_fin) {
> + copied = 0;
> + goto out;
> + }
> + }
> if (!copied) {
> long timeo;
> int data;
tcp_bpf_recvmsg needs a similar fix, no?
next prev parent reply other threads:[~2023-04-03 11:12 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-27 17:54 [PATCH bpf v2 00/11] bpf sockmap fixes John Fastabend
2023-03-27 17:54 ` [PATCH bpf v2 01/12] bpf: sockmap, pass skb ownership through read_skb John Fastabend
2023-03-28 10:42 ` Jakub Sitnicki
2023-03-27 17:54 ` [PATCH bpf v2 02/12] bpf: sockmap, convert schedule_work into delayed_work John Fastabend
2023-03-28 12:09 ` Jakub Sitnicki
2023-03-28 21:56 ` John Fastabend
2023-03-29 11:09 ` Jakub Sitnicki
2023-03-27 17:54 ` [PATCH bpf v2 03/12] bpf: sockmap, improved check for empty queue John Fastabend
2023-03-29 12:24 ` Jakub Sitnicki
2023-04-01 0:59 ` John Fastabend
2023-04-03 8:42 ` Jakub Sitnicki
2023-03-27 17:54 ` [PATCH bpf v2 04/12] bpf: sockmap, handle fin correctly John Fastabend
2023-04-03 11:11 ` Jakub Sitnicki [this message]
2023-04-03 21:05 ` John Fastabend
2023-04-04 10:11 ` Jakub Sitnicki
2023-03-27 17:54 ` [PATCH bpf v2 05/12] bpf: sockmap, TCP data stall on recv before accept John Fastabend
2023-03-27 17:54 ` [PATCH bpf v2 06/12] bpf: sockmap, wake up polling after data copy John Fastabend
2023-03-27 17:54 ` [PATCH bpf v2 07/12] bpf: sockmap incorrectly handling copied_seq John Fastabend
2023-03-27 17:54 ` [PATCH bpf v2 08/12] bpf: sockmap, pull socket helpers out of listen test for general use John Fastabend
2023-03-27 17:54 ` [PATCH bpf v2 09/12] bpf: sockmap, build helper to create connected socket pair John Fastabend
2023-03-27 17:54 ` [PATCH bpf v2 10/12] bpf: sockmap, test shutdown() correctly exits epoll and recv()=0 John Fastabend
2023-03-27 17:54 ` [PATCH bpf v2 11/12] bpf: sockmap, test FIONREAD returns correct bytes in rx buffer John Fastabend
2023-03-27 17:54 ` [PATCH bpf v2 12/12] bpf: sockmap, test FIONREAD returns correct bytes in rx buffer with drops John Fastabend
2023-03-27 18:17 ` [PATCH bpf v2 00/11] bpf sockmap fixes John Fastabend
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