2015-07-24 17:02:12

by Shraddha Barke

Subject: [PATCH 2756/2756] Staging: acpi: Merge lines for immediate return

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 <[email protected]>
---
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

2015-07-24 22:07:04

by Kees Cook

Subject: Re: [PATCH 2756/2756] Staging: acpi: Merge lines for immediate return

On Fri, Jul 24, 2015 at 10:00 AM, Shraddha Barke
<[email protected]> 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 <[email protected]>
> ---
> 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