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Date:   Thu, 24 Nov 2022 19:43:27 +0900
From:   Hyeonggon Yoo <42.hyeyoo@gmail.com>
To:     David Gow <davidgow@google.com>
Cc:     Brendan Higgins <brendan.higgins@linux.dev>,
        Daniel Latypov <dlatypov@google.com>,
        Shuah Khan <skhan@linuxfoundation.org>,
        kunit-dev@googlegroups.com, linux-kselftest@vger.kernel.org,
        linux-kernel@vger.kernel.org, Kees Cook <keescook@chromium.org>,
        linux-doc@vger.kernel.org, linux-mm@kvack.org,
        Oliver Glitta <glittao@gmail.com>,
        Christoph Lameter <cl@linux.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        David Rientjes <rientjes@google.com>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v3 3/3] mm: slub: test: Use the kunit_get_current_test()
 function
Message-ID: <Y39Kz0hI3IOKoqrJ@hyeyoo>
References: <20221119081252.3864249-1-davidgow@google.com>
 <20221119081252.3864249-3-davidgow@google.com>
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On Sat, Nov 19, 2022 at 04:12:52PM +0800, David Gow wrote:
> Use the newly-added function kunit_get_current_test() instead of
> accessing current->kunit_test directly. This function uses a static key
> to return more quickly when KUnit is enabled, but no tests are actively
> running. There should therefore be a negligible performance impact to
> enabling the slub KUnit tests.
> 
> Other than the performance improvement, this should be a no-op.
> 
> Cc: Oliver Glitta <glittao@gmail.com>
> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: David Gow <davidgow@google.com>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>

Acked-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
with small comment:

> ---
> 
> This is intended as an example use of the new function. Other users
> (such as KASAN) will be updated separately, as there would otherwise be
> conflicts.
> 
> We'll take this whole series via the kselftest/kunit tree.
> 
> Changes since v2:
> https://lore.kernel.org/all/20221025071907.1251820-3-davidgow@google.com/
> - Get rid of a redundant 'likely' (Thanks Vlastimil Babka)
> - Use current->kunit_test directly when we already know a test is
>   running. (Thanks Vlastimil Babka)
> - Add Vlastimil's Acked-by.
> 
> There was no v1 of this patch. v1 of the series can be found here:
> https://lore.kernel.org/linux-kselftest/20221021072854.333010-1-davidgow@google.com/T/#u
> 
> Cheers,
> -- David
> 
> ---
>  lib/slub_kunit.c | 1 +
>  mm/slub.c        | 3 ++-
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c
> index 7a0564d7cb7a..8fd19c8301ad 100644
> --- a/lib/slub_kunit.c
> +++ b/lib/slub_kunit.c
> @@ -1,5 +1,6 @@
>  // SPDX-License-Identifier: GPL-2.0
>  #include <kunit/test.h>
> +#include <kunit/test-bug.h>

Is this #include needed in slub_kunit.c?

>  #include <linux/mm.h>
>  #include <linux/slab.h>
>  #include <linux/module.h>
> diff --git a/mm/slub.c b/mm/slub.c
> index 157527d7101b..1887996cb703 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -39,6 +39,7 @@
>  #include <linux/memcontrol.h>
>  #include <linux/random.h>
>  #include <kunit/test.h>
> +#include <kunit/test-bug.h>
>  #include <linux/sort.h>
>  
>  #include <linux/debugfs.h>
> @@ -603,7 +604,7 @@ static bool slab_add_kunit_errors(void)
>  {
>  	struct kunit_resource *resource;
>  
> -	if (likely(!current->kunit_test))
> +	if (!kunit_get_current_test())
>  		return false;
>  
>  	resource = kunit_find_named_resource(current->kunit_test, "slab_errors");
> -- 
> 2.38.1.584.g0f3c55d4c2-goog
> 

-- 
Thanks,
Hyeonggon