Re: [PATCH bpf-next v5] selftests/bpf: trace_helpers.c: optimize kallsyms cache

[Yonghong Song <yonghong.song@linux.dev>]

On 8/20/23 7:03 PM, Rong Tao wrote:
> Sorry Song, I did not state clear.
> 
> libbpf_ensure_mem() is declared in libbpf_internal.h, we want to use
> libbpf_ensure_mem() in trace_helpers.c, Unforturnately, we could only include
> the headers 'install_headers:' defined in tools/lib/bpf/Makefile, the
> 'install_headers:' target does not include libbpf_internal.h, like:
> 
> 	tools/testing/selftests/bpf/trace_helpers.c:17:10:
> 	fatal error: libbpf_internal.h: No such file or directory
> 	   17 | #include "libbpf_internal.h"
> 	      |          ^~~~~~~~~~~~~~~~~~~
> 
> 	tools/testing/selftests/bpf/trace_helpers.c:17:10:
> 	fatal error: bpf/libbpf_internal.h: No such file or directory
> 	   17 | #include "bpf/libbpf_internal.h"
> 	      |           ^~~~~~~~~~~~~~~~~~~~~~~


It works fine for me. On top of your patch, the following works fine:

diff --git a/tools/testing/selftests/bpf/trace_helpers.c 
b/tools/testing/selftests/bpf/trace_helpers.c
index 0053ba22f0cb..087383c5dc3a 100644
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -14,6 +14,7 @@
  #include <linux/limits.h>
  #include <libelf.h>
  #include <gelf.h>
+#include "bpf/libbpf_internal.h"

  #define TRACEFS_PIPE   "/sys/kernel/tracing/trace_pipe"
  #define DEBUGFS_PIPE   "/sys/kernel/debug/tracing/trace_pipe"

With V=1 when building selftests, the following is the compilation
command line:
clang --target=x86_64-linux-gnu -fintegrated-as -g -O0 -rdynamic -Wall 
-Werror   -I/home/yhs/work/bpf-next/tools/testing/selftests/bpf 
-I/home/yhs/work/bpf-next/tools/testing/selftests/bpf/tools/include 
-I/home/yhs/work/bpf-next/include/generated 
-I/home/yhs/work/bpf-next/tools/lib 
-I/home/yhs/work/bpf-next/tools/include 
-I/home/yhs/work/bpf-next/tools/include/uapi 
-I/home/yhs/work/bpf-next/tools/testing/selftests/bpf 
-Wno-unused-command-line-argument  -c trace_helpers.c -lelf -lz -lrt 
-lpthread -o 
/home/yhs/work/bpf-next/tools/testing/selftests/bpf/trace_helpers.o

This include path
   /home/yhs/work/bpf-next/tools/testing/selftests/bpf/tools/include
will make including 'bpf/libbpf_internal.h' work.

> 
> How about
> 
> 1. dup-declare libbpf_ensure_mem() in trace_helpers.c
> 2. move libbpf_ensure_mem() declare into libbpf_common.h
> 
> Which one do you like best.
> 
> Best wishes,
> Rong Tao
> 
>