netdev - Re: [PATCH bpf-next v3 2/2] selftests/bpf: Verifying real time helper function

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Date:   Thu, 24 Sep 2020 17:34:12 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     bimmy.pujari@...el.com, bpf@...r.kernel.org
Cc:     netdev@...r.kernel.org, mchehab@...nel.org, ast@...nel.org,
        kafai@...com, maze@...gle.com, ashkan.nikravesh@...el.com
Subject: Re: [PATCH bpf-next v3 2/2] selftests/bpf: Verifying real time helper
 function

On 9/24/20 4:25 AM, bimmy.pujari@...el.com wrote:
> From: Bimmy Pujari <bimmy.pujari@...el.com>
> 
> Test xdping measures RTT from xdp using monotonic time helper.
> Extending xdping test to use real time helper function in order
> to verify this helper function.
> 
> Signed-off-by: Bimmy Pujari <bimmy.pujari@...el.com>
[...]
> diff --git a/tools/testing/selftests/bpf/progs/xdping_realtime_kern.c b/tools/testing/selftests/bpf/progs/xdping_realtime_kern.c
> new file mode 100644
> index 000000000000..85f9d9bfc5b7
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/xdping_realtime_kern.c
> @@ -0,0 +1,4 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#define REALTIME
> +

Instead of moving everything into xdping_kern.h and then adding a REALTIME define just
for doing ...

   +#ifdef REALTIME
   +	recvtime = bpf_ktime_get_real_ns();
   +#else
   +	recvtime = bpf_ktime_get_ns();
   +#endif

... why not simply just provide a small inline helper with the bpf_ktime_*() implementation
instead so we can avoid the ugly ifdef altogether..

> +#include "xdping_kern.h"
> diff --git a/tools/testing/selftests/bpf/test_xdping.sh b/tools/testing/selftests/bpf/test_xdping.sh
> index c2f0ddb45531..3e357755b279 100755
> --- a/tools/testing/selftests/bpf/test_xdping.sh
[...]