From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Yonghong Song <yhs@fb.com>
Cc: Andrii Nakryiko <andriin@fb.com>,
bpf@vger.kernel.org, Martin KaFai Lau <kafai@fb.com>,
netdev@vger.kernel.org, Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
kernel-team@fb.com
Subject: Re: [PATCH bpf-next v4 21/21] tools/bpf: selftests: add bpf_iter selftests
Date: Sat, 9 May 2020 17:34:02 -0700 [thread overview]
Message-ID: <20200510003402.3a4ozoynwm4mryi5@ast-mbp> (raw)
In-Reply-To: <20200509175923.2477637-1-yhs@fb.com>
On Sat, May 09, 2020 at 10:59:23AM -0700, Yonghong Song wrote:
> +static volatile const __u32 ret1;
> +
> +SEC("iter/bpf_map")
> +int dump_bpf_map(struct bpf_iter__bpf_map *ctx)
> +{
> + struct seq_file *seq = ctx->meta->seq;
> + struct bpf_map *map = ctx->map;
> + __u64 seq_num;
> + int i, ret = 0;
> +
> + if (map == (void *)0)
> + return 0;
> +
> + /* only dump map1_id and map2_id */
> + if (map->id != map1_id && map->id != map2_id)
> + return 0;
> +
> + seq_num = ctx->meta->seq_num;
> + if (map->id == map1_id) {
> + map1_seqnum = seq_num;
> + map1_accessed++;
> + }
> +
> + if (map->id == map2_id) {
> + if (map2_accessed == 0) {
> + map2_seqnum1 = seq_num;
> + if (ret1)
> + ret = 1;
> + } else {
> + map2_seqnum2 = seq_num;
> + }
> + map2_accessed++;
> + }
> +
> + /* fill seq_file buffer */
> + for (i = 0; i < print_len; i++)
> + bpf_seq_write(seq, &seq_num, sizeof(seq_num));
> +
> + return ret;
> +}
I couldn't find where 'return 1' behavior is documented clearly.
I think it's a workaround for overflow.
When bpf prog detects overflow it can request replay of the element?
What if it keeps returning 1 ? read() will never finish?
next prev parent reply other threads:[~2020-05-10 0:34 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-09 17:58 [PATCH bpf-next v4 00/21] bpf: implement bpf iterator for kernel data Yonghong Song
2020-05-09 17:58 ` [PATCH bpf-next v4 01/21] bpf: implement an interface to register bpf_iter targets Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 02/21] bpf: allow loading of a bpf_iter program Yonghong Song
2020-05-10 0:41 ` Alexei Starovoitov
2020-05-10 5:07 ` Yonghong Song
2020-05-12 15:41 ` Yonghong Song
2020-05-12 16:25 ` Alexei Starovoitov
2020-05-12 16:29 ` Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 03/21] bpf: support bpf tracing/iter programs for BPF_LINK_CREATE Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 04/21] bpf: support bpf tracing/iter programs for BPF_LINK_UPDATE Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 05/21] bpf: implement bpf_seq_read() for bpf iterator Yonghong Song
2020-05-10 0:30 ` Alexei Starovoitov
2020-05-10 4:51 ` Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 06/21] bpf: create anonymous " Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 07/21] bpf: create file " Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 08/21] bpf: implement common macros/helpers for target iterators Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 09/21] bpf: add bpf_map iterator Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 10/21] net: bpf: add netlink and ipv6_route bpf_iter targets Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 11/21] bpf: add task and task/file iterator targets Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 12/21] bpf: add PTR_TO_BTF_ID_OR_NULL support Yonghong Song
2020-05-10 0:50 ` Alexei Starovoitov
2020-05-10 5:18 ` Yonghong Song
2020-05-10 16:11 ` Alexei Starovoitov
2020-05-10 17:05 ` Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 13/21] bpf: add bpf_seq_printf and bpf_seq_write helpers Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 14/21] bpf: handle spilled PTR_TO_BTF_ID properly when checking stack_boundary Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 15/21] bpf: support variable length array in tracing programs Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 16/21] tools/libbpf: add bpf_iter support Yonghong Song
2020-05-10 0:35 ` Alexei Starovoitov
2020-05-10 5:06 ` Yonghong Song
2020-05-10 16:09 ` Alexei Starovoitov
2020-05-10 17:04 ` Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 17/21] tools/libpf: add offsetof/container_of macro in bpf_helpers.h Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 18/21] tools/bpftool: add bpf_iter support for bptool Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 19/21] tools/bpf: selftests: add iterator programs for ipv6_route and netlink Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 20/21] tools/bpf: selftests: add iter progs for bpf_map/task/task_file Yonghong Song
2020-05-09 17:59 ` [PATCH bpf-next v4 21/21] tools/bpf: selftests: add bpf_iter selftests Yonghong Song
2020-05-10 0:34 ` Alexei Starovoitov [this message]
2020-05-10 5:01 ` Yonghong Song
2020-05-10 16:14 ` Alexei Starovoitov
2020-05-10 0:27 ` [PATCH bpf-next v4 00/21] bpf: implement bpf iterator for kernel data Alexei Starovoitov
2020-05-10 4:47 ` Yonghong Song
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