Re: [PATCH v2 bpf-next 2/3] libbpf: introduce bpf_prog_test_run_xattr_opts

On Sep 23, 2020, at 12:31 PM, Andrii Nakryiko [off-list ref] wrote:

On Wed, Sep 23, 2020 at 9:55 AM Song Liu [off-list ref] wrote:

quoted

This API supports new field cpu_plus in bpf_attr.test.

Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Song Liu <redacted>
---
tools/lib/bpf/bpf.c      | 13 ++++++++++++-
tools/lib/bpf/bpf.h      | 11 +++++++++++
tools/lib/bpf/libbpf.map |  1 +
3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 2baa1308737c8..3228dd60fa32f 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c

@@ -684,7 +684,8 @@ int bpf_prog_test_run(int prog_fd, int repeat, void *data, __u32 size,
       return ret;

}

-int bpf_prog_test_run_xattr(struct bpf_prog_test_run_attr *test_attr)
+int bpf_prog_test_run_xattr_opts(struct bpf_prog_test_run_attr *test_attr,
+                                const struct bpf_prog_test_run_opts *opts)

opts are replacement for test_attr, not an addition to it. We chose to
use _xattr suffix for low-level APIs previously, but it's already
"taken". So I'd suggest to go with just  bpf_prog_test_run_ops and
have prog_fd as a first argument and then put all the rest of
test_run_attr into opts.

One question on this: from the code, most (if not all) of these xxx_opts
are used as input only. For example:

LIBBPF_API int bpf_prog_bind_map(int prog_fd, int map_fd,
                                 const struct bpf_prog_bind_opts *opts);

However, bpf_prog_test_run_attr contains both input and output. Do you
have any concern we use bpf_prog_test_run_opts for both input and output?

Thanks,
Song

BTW, it's also probably overdue to have a higher-level
bpf_program__test_run(), which can re-use the same
bpf_prog_test_run_opts options struct. It would be more convenient to
use it with libbpf bpf_object/bpf_program APIs.

quoted

{
       union bpf_attr attr;
       int ret;

@@ -693,6 +694,11 @@ int bpf_prog_test_run_xattr(struct bpf_prog_test_run_attr *test_attr)
               return -EINVAL;

       memset(&attr, 0, sizeof(attr));
+       if (opts) {

you don't need to check opts for being not NULL, OPTS_VALID handle that already.

quoted

+               if (!OPTS_VALID(opts, bpf_prog_test_run_opts))
+                       return -EINVAL;
+               attr.test.cpu_plus = opts->cpu_plus;

And here you should use OPTS_GET(), please see other examples in
libbpf for proper usage.

quoted

+       }
       attr.test.prog_fd = test_attr->prog_fd;
       attr.test.data_in = ptr_to_u64(test_attr->data_in);
       attr.test.data_out = ptr_to_u64(test_attr->data_out);

@@ -712,6 +718,11 @@ int bpf_prog_test_run_xattr(struct bpf_prog_test_run_attr *test_attr)
       return ret;

}

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