linux-kernel - Re: [PATCH 2756/2756] Staging: acpi: Merge lines for immediate return

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Message-ID: <CAGXu5jJAWcfA63CtZULYTzTUu2Gyx1pMbV0g45PhfDq+k9PtSQ@mail.gmail.com>
Date:	Fri, 24 Jul 2015 15:07:00 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Shraddha Barke <shraddha.6596@...il.com>
Cc:	Anton Vorontsov <anton@...msg.org>,
	Colin Cross <ccross@...roid.com>,
	Tony Luck <tony.luck@...el.com>, linux-acpi@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2756/2756] Staging: acpi: Merge lines for immediate return

On Fri, Jul 24, 2015 at 10:00 AM, Shraddha Barke
<shraddha.6596@...il.com> wrote:
> This patch merges two lines in a single line if immediate return is found.
> This is done using Coccinelle.Semantic patch used for this is as follows:
>
> @@
> expression ret;
> identifier f;
> @@
>
> -ret =
> +return
>      f(...);
> -return ret;
>
> Signed-off-by: Shraddha Barke <shraddha.6596@...il.com>
> ---
>  drivers/acpi/apei/erst.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c
> index 3670bba..58e1bdd 100644
> --- a/drivers/acpi/apei/erst.c
> +++ b/drivers/acpi/apei/erst.c
> @@ -162,8 +162,7 @@ static int erst_exec_add_value(struct apei_exec_context *ctx,
>         if (rc)
>                 return rc;
>         val += ctx->value;
> -       rc = __apei_exec_write_register(entry, val);
> -       return rc;
> +       return __apei_exec_write_register(entry, val);
>  }
>
>  static int erst_exec_subtract_value(struct apei_exec_context *ctx,
> @@ -176,8 +175,7 @@ static int erst_exec_subtract_value(struct apei_exec_context *ctx,
>         if (rc)
>                 return rc;
>         val -= ctx->value;
> -       rc = __apei_exec_write_register(entry, val);
> -       return rc;
> +       return __apei_exec_write_register(entry, val);
>  }
>
>  static int erst_exec_stall(struct apei_exec_context *ctx,
> @@ -979,9 +977,7 @@ static int erst_open_pstore(struct pstore_info *psi)
>         if (erst_disable)
>                 return -ENODEV;
>
> -       rc = erst_get_record_id_begin(&reader_pos);
> -
> -       return rc;
> +       return erst_get_record_id_begin(&reader_pos);
>  }
>
>  static int erst_close_pstore(struct pstore_info *psi)
> --
> 2.1.0
>

Personally I prefer the readability of continuing to use the rest of a
function's rc = ..., if (rc) ... semantics. If "rc" could be entirely
removed from the function, then switching to immediate returns seems
like a reasonable cleanup. Otherwise, I think it reduces readability
for no effect (the compiler, for example, is already optimizing these
kinds of things at build-time).

-Kees

-- 
Kees Cook
Chrome OS Security
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