Re: [PATCH bpf-next v2 2/2] selftests/bpf: Verify is_extended with multiple freplace links

[Leon Hwang <leon.hwang@linux.dev>]

On 24/9/26 10:37, chenyuan_fl@163.com wrote:
> From: Yuan Chen <chenyuan@kylinos.cn>
> 
> Extend tc_bpf2bpf with two freplace links, one on entry_tc and one on
> subprog_tc, and detach the one on the entry: while subprog_tc is still
> extended, updating entry_tc into a prog_array map must keep failing
> with -EBUSY, and succeed again once the last link detaches.  The test
> asserts the rejection instead of running the prog, as the update
> succeeds and the prog loops unbounded on an unfixed kernel.
> 
> Signed-off-by: Yuan Chen <chenyuan@kylinos.cn>
> ---
>  .../selftests/bpf/prog_tests/tailcalls.c      | 74 +++++++++++++++++++
>  .../bpf/progs/tailcall_freplace_multi.c       | 27 +++++++
>  2 files changed, 101 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/progs/tailcall_freplace_multi.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/tailcalls.c b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
> index c5c9d6c359bb..aefb46778307 100644
> --- a/tools/testing/selftests/bpf/prog_tests/tailcalls.c
> +++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c
> @@ -6,6 +6,7 @@
>  #include "tailcall_bpf2bpf_hierarchy2.skel.h"
>  #include "tailcall_bpf2bpf_hierarchy3.skel.h"
>  #include "tailcall_freplace.skel.h"
> +#include "tailcall_freplace_multi.skel.h"
>  #include "tc_bpf2bpf.skel.h"
>  #include "tailcall_fail.skel.h"
>  #include "tailcall_cgrp_storage_owner.skel.h"
> @@ -1655,6 +1656,77 @@ static void test_tailcall_bpf2bpf_freplace(void)
>  	tc_bpf2bpf__destroy(tc_skel);
>  }
>  
> +static void test_tailcall_freplace_multi(void)
> +{
> +	struct tailcall_freplace_multi *freplace_skel = NULL;
> +	struct bpf_link *link_subprog = NULL, *link_entry = NULL;
> +	struct tc_bpf2bpf *tc_skel = NULL;
> +	int tc_prog_fd, map_fd, key = 0, err;


Pls keep the above lines with inverted Christmas tree style.

And, drop '= NULL' for tc_skel, because tc_skel is the first variable to
be initialized.

Thanks,
Leon

> +
> +	tc_skel = tc_bpf2bpf__open_and_load();
> +	if (!ASSERT_OK_PTR(tc_skel, "tc_bpf2bpf__open_and_load"))
> +		return;
> [...]