Re: [PATCH v2 bpf-next 04/17] libbpf: Add support to attach to fentry/fexit tracing progs

On Nov 7, 2019, at 3:07 PM, Alexei Starovoitov [off-list ref] wrote:

On Thu, Nov 07, 2019 at 10:51:41PM +0000, Song Liu wrote:

quoted

quoted

On Nov 6, 2019, at 9:46 PM, Alexei Starovoitov [off-list ref] wrote:

Teach libbpf to recognize tracing programs types and attach them to
fentry/fexit.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Acked-by: Song Liu <redacted>

With nit below:

quoted

---
tools/include/uapi/linux/bpf.h |  2 ++
tools/lib/bpf/libbpf.c         | 61 +++++++++++++++++++++++++++++-----
tools/lib/bpf/libbpf.h         |  5 +++
tools/lib/bpf/libbpf.map       |  2 ++
4 files changed, 61 insertions(+), 9 deletions(-)

[...]

quoted

/* Accessors of bpf_program */
struct bpf_program;

@@ -248,6 +251,8 @@ LIBBPF_API struct bpf_link *

bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
				   const char *tp_name);

+LIBBPF_API struct bpf_link *
+bpf_program__attach_trace(struct bpf_program *prog);
struct bpf_insn;

attach_trace is not very clear. I guess we cannot call it 
attach_ftrace? Maybe we call it attach_fentry and attach_fexit
(two names pointing to same function)? 

bpf_program__attach_trace() can attach all BPF_PROG_TYPE_TRACING.
Which today are:
       BPF_TRACE_RAW_TP,
       BPF_TRACE_FENTRY,
       BPF_TRACE_FEXIT,
There will be more BPF_TRACE_* enum bpf_attach_type in the future.
I considered naming it bpf_program__attach_tracing(), but it's uglier
and longer.

I see. Thanks for the explanation. 

Song