Hello Yonghong,
On Mon, Nov 20, 2023 at 07:22:59AM -0800, Yonghong Song wrote:
> > -           if (CHECK(!err || errno != ENOENT,
> > -                     "bpf_map_lookup_elem(sk_stg_map)",
> > -                     "err:%d errno:%d\n", err, errno))
> > +           if (!ASSERT_NEQ(err, 0, "bpf_map_lookup_elem(sk_stg_map)") ||
> 
> !ASSERT_ERR(err, "bpf_map_lookup_elem(sk_stg_map)")
> might be simpler than !ASSERT_NEQ(..).
> 
Sure, that makes sense. I'll change it in v3.
> > -   pthread_join(srv_thread, &thread_ret);
> > -   CHECK(IS_ERR(thread_ret), "pthread_join", "thread_ret:%ld",
> > -         PTR_ERR(thread_ret));
> > +   err = pthread_join(srv_thread, &thread_ret);
> > +   ASSERT_OK(err, "pthread_join");
> 
> The above is not equivalent to the original code.
> The original didn't check pthread_join() return as it
> is very very unlikely to fail. And check 'thread_ret'
> is still needed.
> 
Yes that is true, but the v1 [1] broke the tests because the
ASSERT_OK_PTR(thread_ret, "pthread_join") kept failing, even
though all the asserts within the `server()` function itself
passed.

Also, isn't asserting `thread_ret` technically checking the
`server()` function instead of `pthread_join`? So should we
have two asserts here? One for `server` and one for `pthread_join`
or is it not necessary?
i.e:
```
ASSERT_OK_PTR(thread_ret, "server");
ASSERT_OK(err, "pthread_join");
```

Upon taking a second look, I now think that the reason why
`ASSERT_OK_PTR(thread_ret, "pthread_join");` failed in v1 might
have been because it calls `libbpf_get_error` which returns
`-errno` when the pointer is `NULL`.

Since `server`'s return value is not a bpf address, which
`ASSERT_OK_PTR` expects it to be, do you that think we should
explicitly set `errno = 0` prior to returning NULL on server?
That way that assert would pass even when the pointer is NULL
(which is the case when `server` returns successfuly).

[1] - 
https://lore.kernel.org/lkml/gv1pr10mb6563a0be91080e6e8ec2651de8...@gv1pr10mb6563.eurprd10.prod.outlook.com/

As always, thank you for your feedback.

Yuran Pereira

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