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@lkp-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.c...@intel.com>
Signed-off-by: Yonghong Song <y...@fb.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 <j...@resnulli.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

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