Re: [PATCH bpf-next 1/9] selftests: bpf: move tracing helpers to trace_helper

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Tue, Nov 17, 2020 at 6:57 AM Daniel T. Lee <danieltimlee@gmail.com> wrote:
>
> Under the samples/bpf directory, similar tracing helpers are
> fragmented around. To keep consistent of tracing programs, this commit
> moves the helper and define locations to increase the reuse of each
> helper function.
>
> Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
>
> ---
>  samples/bpf/Makefile                        |  2 +-
>  samples/bpf/hbm.c                           | 51 ++++-----------------
>  tools/testing/selftests/bpf/trace_helpers.c | 33 ++++++++++++-
>  tools/testing/selftests/bpf/trace_helpers.h |  3 ++
>  4 files changed, 45 insertions(+), 44 deletions(-)
>
> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> index aeebf5d12f32..3e83cd5ca1c2 100644
> --- a/samples/bpf/Makefile
> +++ b/samples/bpf/Makefile
> @@ -110,7 +110,7 @@ xdp_fwd-objs := xdp_fwd_user.o
>  task_fd_query-objs := bpf_load.o task_fd_query_user.o $(TRACE_HELPERS)
>  xdp_sample_pkts-objs := xdp_sample_pkts_user.o $(TRACE_HELPERS)
>  ibumad-objs := bpf_load.o ibumad_user.o $(TRACE_HELPERS)
> -hbm-objs := bpf_load.o hbm.o $(CGROUP_HELPERS)
> +hbm-objs := bpf_load.o hbm.o $(CGROUP_HELPERS) $(TRACE_HELPERS)
>
>  # Tell kbuild to always build the programs
>  always-y := $(tprogs-y)
> diff --git a/samples/bpf/hbm.c b/samples/bpf/hbm.c
> index 400e741a56eb..b9f9f771dd81 100644
> --- a/samples/bpf/hbm.c
> +++ b/samples/bpf/hbm.c
> @@ -48,6 +48,7 @@
>
>  #include "bpf_load.h"
>  #include "bpf_rlimit.h"
> +#include "trace_helpers.h"
>  #include "cgroup_helpers.h"
>  #include "hbm.h"
>  #include "bpf_util.h"
> @@ -65,51 +66,12 @@ bool no_cn_flag;
>  bool edt_flag;
>
>  static void Usage(void);
> -static void read_trace_pipe2(void);
>  static void do_error(char *msg, bool errno_flag);
>
> -#define DEBUGFS "/sys/kernel/debug/tracing/"
> -
>  struct bpf_object *obj;
>  int bpfprog_fd;
>  int cgroup_storage_fd;
>
> -static void read_trace_pipe2(void)

This is used only in hbm.c, why move it into trace_helpers.c?

> -{
> -       int trace_fd;
> -       FILE *outf;
> -       char *outFname = "hbm_out.log";
> -

[...]