Re: [PATCH net-next 2/2] tools lib bpf: export function to set type

[Wangnan (F)]

On 2016/8/13 20:17, Eric Leblond wrote:

Current API was not allowing the user to set a type like socket
filter. To avoid a setter function for each type, the patch simply
exports a set function that takes the type in parameter.

Signed-off-by: Eric Leblond <e...@regit.org>
---
  tools/lib/bpf/libbpf.c | 15 ++++++---------
  tools/lib/bpf/libbpf.h |  3 +++
  2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7872ff6..ff2a8c6 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1336,26 +1336,23 @@ int bpf_program__nth_fd(struct bpf_program *prog, int n)
        return fd;
  }

-static void bpf_program__set_type(struct bpf_program *prog,

+int bpf_program__set_type(struct bpf_program *prog,
                                  enum bpf_prog_type type)
  {
+       if (!prog)
+               return -EINVAL;
        prog->type = type;
+       return 0;
  }

We'd better add a sanity check here to prevent setting invalid
program type. Plase have a look at

https://lkml.org/lkml/2015/12/17/13

  int bpf_program__set_tracepoint(struct bpf_program *prog)
  {
-       if (!prog)
-               return -EINVAL;
-       bpf_program__set_type(prog, BPF_PROG_TYPE_TRACEPOINT);
-       return 0;
+       return bpf_program__set_type(prog, BPF_PROG_TYPE_TRACEPOINT);
  }

int bpf_program__set_kprobe(struct bpf_program *prog)

  {
-       if (!prog)
-               return -EINVAL;
-       bpf_program__set_type(prog, BPF_PROG_TYPE_KPROBE);
-       return 0;
+       return bpf_program__set_type(prog, BPF_PROG_TYPE_KPROBE);
  }

static bool bpf_program__is_type(struct bpf_program *prog,

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index a6c5cde..6a84d7a 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -173,6 +173,9 @@ int bpf_program__set_kprobe(struct bpf_program *prog);
  bool bpf_program__is_tracepoint(struct bpf_program *prog);
  bool bpf_program__is_kprobe(struct bpf_program *prog);

+int bpf_program__set_type(struct bpf_program *prog,

+                                 enum bpf_prog_type type);
+

This makes libbpf.h depend on kernel's uapi/linux/bpf.h.
Although I did this in the above patch, I don't like this
dependency. This is the reason why I introduce

int bpf_program__set_tracepoint(struct bpf_program *prog);
int bpf_program__set_kprobe(struct bpf_program *prog);

bool bpf_program__is_tracepoint(struct bpf_program *prog);
bool bpf_program__is_kprobe(struct bpf_program *prog);

and hide bpf_program__set_type inside the .c file.

Please add type setting functions, or pass int value to
bpf_program__set_type and add sanity checking.

Thank you.