[DTrace-devel] [PATCH 03/12] Check that stackdepth is nonzero in test

[Kris Van Hees]

On Fri, May 28, 2021 at 02:35:07PM -0400, eugene.loh at oracle.com wrote:
> From: Eugene Loh <eugene.loh at oracle.com>
> 
> This test was passing gratuitously since neither stack() nor
> stackdepth was working properly:  stack() reported nothing and
> stackdepth always reported 0.  Change the test to require a
> nonempty stack.  For now, the test will XFAIL.

This is a bit of a judgement call I guess.  The purpose of the test is to
validate that the stackdepth is consistent with the stack() output.  When
stack() reports no data and stackdepth returns 0, I would argue that the
test is allowed to PASS.  Furthermore, once stack() is implemented (as you
do in followup patches), this test remains valid and becomes more important
to ensure that stack() and stackdepth remain in sync.

So, I would actually just leave out this patch because it is not needed.
And if there is a circumstance where a stack() could validly be empty (i.e.
where the stack up to the probe itself is to be ignored because it is part
of the calling mechanism or something like that).  Even if that is very
unlikely, I don't think we should discount it.

And there is no loss to keeping this test as-is.

> Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
> ---
>  test/unittest/stackdepth/tst.value.d   | 3 ++-
>  test/unittest/stackdepth/tst.value.r.p | 4 +++-
>  2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/test/unittest/stackdepth/tst.value.d b/test/unittest/stackdepth/tst.value.d
> index 857728bd..97cc54df 100644
> --- a/test/unittest/stackdepth/tst.value.d
> +++ b/test/unittest/stackdepth/tst.value.d
> @@ -1,9 +1,10 @@
>  /*
>   * Oracle Linux DTrace.
> - * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
> + * Copyright (c) 2006, 2021, Oracle and/or its affiliates. All rights reserved.
>   * Licensed under the Universal Permissive License v 1.0 as shown at
>   * http://oss.oracle.com/licenses/upl.
>   */
> +/* @@xfail: dtv2 */
>  
>  #pragma D option quiet
>  
> diff --git a/test/unittest/stackdepth/tst.value.r.p b/test/unittest/stackdepth/tst.value.r.p
> index d5143e38..fa83eb0c 100755
> --- a/test/unittest/stackdepth/tst.value.r.p
> +++ b/test/unittest/stackdepth/tst.value.r.p
> @@ -1,6 +1,6 @@
>  #!/usr/bin/gawk -f
>  # Oracle Linux DTrace.
> -# Copyright (c) 2016, 2020, Oracle and/or its affiliates. All rights reserved.
> +# Copyright (c) 2016, 2021, Oracle and/or its affiliates. All rights reserved.
>  # Licensed under the Universal Permissive License v 1.0 as shown at
>  # http://oss.oracle.com/licenses/upl.
>  
> @@ -26,6 +26,8 @@ END {
>  		printf "Stack depth too large (%d > %d)\n", depth, count;
>  	else if (count > depth)
>  		printf "Stack depth too small (%d < %d)\n", depth, count;
> +	else if (count == 0)
> +		printf "Stack depth is 0\n";
>  	else
>  		printf "Stack depth OK\n";
>  }
> -- 
> 2.18.4
> 
> 
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