Re: [PATCH bpf-next v6 3/3] selftests/bpf: Add cases to test tailcall in freplace

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

On 9/10/24 13:04, Eduard Zingerman wrote:
> On Wed, 2024-10-09 at 00:13 +0800, Leon Hwang wrote:
>> cd tools/testing/selftests/bpf; ./test_progs -t tailcalls
>> 335/27  tailcalls/tailcall_bpf2bpf_hierarchy_freplace_1:OK
>> 335/28  tailcalls/tailcall_bpf2bpf_hierarchy_freplace_2:OK
>> 335     tailcalls:OK
>> Summary: 1/28 PASSED, 0 SKIPPED, 0 FAILED
>>
>> Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
>> ---
> 
> Tbh, I don't think these tests are necessary.
> Patch #2 already covers changes in patch #1.
> 
> [...]
> 

You are right.

I should provide the commit message to tell the reason why to add these
two test cases:

In order to confirm tailcall in freplace is OK and won't be broken by
patch of preventing tailcall infinite loop caused by freplace or other
patches in the future, add two test cases to confirm that freplace is OK
to tail call itself or other freplace prog, even if the target prog of
freplace is a subprog and the subprog is called many times in its caller.

Thanks,
Leon