netdev - Re: [PATCH bpf] tools/bpftool: copy uapi/linux/tc_act/tc

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Message-ID: <149eb435-a9b5-da31-9f72-52168a9058f4@intel.com>
Date:   Thu, 8 Nov 2018 09:15:24 +0800
From:   Li Zhijian <zhijianx.li@...el.com>
To:     Yonghong Song <yhs@...com>, ast@...com, kafai@...com,
        daniel@...earbox.net, netdev@...r.kernel.org, rong.a.chen@...el.com
Cc:     kernel-team@...com
Subject: Re: [PATCH bpf] tools/bpftool: copy uapi/linux/tc_act/tc_bpf.h to
 tools directory

On 11/8/2018 9:00 AM, Yonghong Song wrote:
> Commit f6f3bac08ff9 ("tools/bpf: bpftool: add net support")
> added certain networking support to bpftool.
> The implementation relies on a relatively recent uapi header file
> linux/tc_act/tc_bpf.h on the host which contains the marco
> definition of TCA_ACT_BPF_ID.
>
> Unfortunately, this is not the case for all distributions.
> See the email message below where rhel-7.2 does not have
> an up-to-date linux/tc_act/tc_bpf.h.
>    https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1799211.html

i have not tested this patch, but basing on the early commit
6f3bac08ff9 ("tools/bpf: bpftool: add net support")
i cooked up similar patch locally, but i noticed that it also requires an
up-to-date linux/pkt_cls.h as well to avoid compiling errors:

root@...-bdw-ep3 ~/linux-f6f3bac08f/tools/bpf/bpftool# make V=1
[...snip...]
gcc -O2 -W -Wall -Wextra -Wno-unused-parameter -Wshadow -Wno-missing-field-initializers -DPACKAGE='"bpftool"' -D__EXPORTED_HEADERS__ -I/root/linux-f6f3bac08f/kernel/bpf/ -I/root/linux-f6f3bac08f/tools/include -I/root/linux-f6f3bac08f/tools/include/uapi -I/root/linux-f6f3bac08f/tools/lib/bpf -I/root/linux-f6f3bac08f/tools/perf -DBPFTOOL_VERSION='"4.19.0-rc2"' -DCOMPAT_NEED_REALLOCARRAY   -c -MMD -o netlink_dumper.o netlink_dumper.c
make -C /root/linux-f6f3bac08f/tools/lib/bpf/ OUTPUT= libbpf.a
make[1]: Entering directory '/root/linux-f6f3bac08f/tools/lib/bpf'
netlink_dumper.c: In function 'do_bpf_filter_dump':
netlink_dumper.c:153:9: error: 'TCA_BPF_ID' undeclared (first use in this function)
   if (tb[TCA_BPF_ID])
          ^~~~~~~~~~
netlink_dumper.c:153:9: note: each undeclared identifier is reported only once for each function it appears in
netlink_dumper.c:155:9: error: 'TCA_BPF_TAG' undeclared (first use in this function)
   if (tb[TCA_BPF_TAG])
          ^~~~~~~~~~~
Makefile:96: recipe for target 'netlink_dumper.o' failed
make: *** [netlink_dumper.o] Error 1
make: *** Waiting for unfinished jobs....
make -f /root/linux-f6f3bac08f/tools/build/Makefile.build dir=. obj=libbpf
make[1]: Leaving directory '/root/linux-f6f3bac08f/tools/lib/bpf'

Thanks
Zhijian

>
> This patch fixed the issue by copying linux/tc_act/tc_bpf.h from
> kernel include/uapi directory to tools/include/uapi directory so
> building the bpftool does not depend on host system for this file.
>
> Fixes: f6f3bac08ff9 ("tools/bpf: bpftool: add net support")
> Reported-by: kernel test robot <rong.a.chen@...el.com>
> Signed-off-by: Yonghong Song <yhs@...com>
> ---
>   tools/include/uapi/linux/tc_act/tc_bpf.h | 37 ++++++++++++++++++++++++
>   1 file changed, 37 insertions(+)
>   create mode 100644 tools/include/uapi/linux/tc_act/tc_bpf.h
>
> diff --git a/tools/include/uapi/linux/tc_act/tc_bpf.h b/tools/include/uapi/linux/tc_act/tc_bpf.h
> new file mode 100644
> index 000000000000..6e89a5df49a4
> --- /dev/null
> +++ b/tools/include/uapi/linux/tc_act/tc_bpf.h
> @@ -0,0 +1,37 @@
> +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
> +/*
> + * Copyright (c) 2015 Jiri Pirko <jiri@...nulli.us>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#ifndef __LINUX_TC_BPF_H
> +#define __LINUX_TC_BPF_H
> +
> +#include <linux/pkt_cls.h>
> +
> +#define TCA_ACT_BPF 13
> +
> +struct tc_act_bpf {
> +	tc_gen;
> +};
> +
> +enum {
> +	TCA_ACT_BPF_UNSPEC,
> +	TCA_ACT_BPF_TM,
> +	TCA_ACT_BPF_PARMS,
> +	TCA_ACT_BPF_OPS_LEN,
> +	TCA_ACT_BPF_OPS,
> +	TCA_ACT_BPF_FD,
> +	TCA_ACT_BPF_NAME,
> +	TCA_ACT_BPF_PAD,
> +	TCA_ACT_BPF_TAG,
> +	TCA_ACT_BPF_ID,
> +	__TCA_ACT_BPF_MAX,
> +};
> +#define TCA_ACT_BPF_MAX (__TCA_ACT_BPF_MAX - 1)
> +
> +#endif