linux-kernel - Re: [PATCH 2/6] scs: Move accounting into alloc/free functions

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Message-ID: <20200518113858.GB1957@C02TD0UTHF1T.local>
Date:   Mon, 18 May 2020 12:38:58 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Will Deacon <will@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Mark Rutland <mark.rutland@...com>,
        Jann Horn <jannh@...gle.com>, Ard Biesheuvel <ardb@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>, kernel-team@...roid.com
Subject: Re: [PATCH 2/6] scs: Move accounting into alloc/free functions

On Fri, May 15, 2020 at 06:27:52PM +0100, Will Deacon wrote:
> There's no need to perform the shadow stack page accounting independently
> of the lifetime of the underlying allocation, so call the accounting code
> from the {alloc,free}() functions and simplify the code in the process.
> 
> Signed-off-by: Will Deacon <will@...nel.org>
> ---
>  kernel/scs.c | 45 +++++++++++++++++++++------------------------
>  1 file changed, 21 insertions(+), 24 deletions(-)

One (super trivial) nit below, but regardless this looks like a sound
and sensible cleanup, so:

Reviewed-by: Mark Rutland <mark.rutland@....com>

> diff --git a/kernel/scs.c b/kernel/scs.c
> index 5ff8663e4a67..aea841cd7586 100644
> --- a/kernel/scs.c
> +++ b/kernel/scs.c
> @@ -14,25 +14,35 @@

>  static void *scs_alloc(int node)
>  {

> +	void *s = kmem_cache_alloc_node(scs_cache, GFP_SCS, node);
> +
> +	if (!s)
> +		return NULL;

Super trivial nit, but could we omit the line space between these two,
to fit with usual style?

Mark.