2017-07-11 18:40:07

by Gustavo A. R. Silva

Subject: [PATCH] pinctrl: qcom: ssbi-gpio: constify gpio_chip structure

This structure is only used to copy into other structure, so declare
it as const.

This issue was detected using Coccinelle and the following semantic patch:

@r disable optional_qualifier@
identifier i;
position p;
@@
static struct gpio_chip i@p = { ... };

@ok@
identifier r.i;
expression e;
position p;
@@
e = i@p;

@bad@
position p != {r.p,ok.p};
identifier r.i;
struct gpio_chip e;
@@
e@i@p

@depends on !bad disable optional_qualifier@
identifier r.i;
@@
static
+const
struct gpio_chip i = { ... };

In the following log you can see a significant difference in the code size
and data segment, hence in the dec segment. This log is the output
of the size command, before and after the code change:

before:
text data bss dec hex filename
17061 6992 0 24053 5df5 drivers/pinctrl/qcom/pinctrl-ssbi-gpio.o

after:
text data bss dec hex filename
16777 6904 0 23681 5c81 drivers/pinctrl/qcom/pinctrl-ssbi-gpio.o

Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c b/drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c
index d3f5501d..f53e32a 100644
--- a/drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c
+++ b/drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c
@@ -588,7 +588,7 @@ static void pm8xxx_gpio_dbg_show(struct seq_file *s, struct gpio_chip *chip)
#define pm8xxx_gpio_dbg_show NULL
#endif

-static struct gpio_chip pm8xxx_gpio_template = {
+static const struct gpio_chip pm8xxx_gpio_template = {
.direction_input = pm8xxx_gpio_direction_input,
.direction_output = pm8xxx_gpio_direction_output,
.get = pm8xxx_gpio_get,
--
2.5.0

2017-07-11 21:42:56

by Bjorn Andersson

Subject: Re: [PATCH] pinctrl: qcom: ssbi-gpio: constify gpio_chip structure

On Tue 11 Jul 11:39 PDT 2017, Gustavo A. R. Silva wrote:

[..]
> before:
> text data bss dec hex filename
> 17061 6992 0 24053 5df5 drivers/pinctrl/qcom/pinctrl-ssbi-gpio.o
>
> after:
> text data bss dec hex filename
> 16777 6904 0 23681 5c81 drivers/pinctrl/qcom/pinctrl-ssbi-gpio.o
>
> Signed-off-by: Gustavo A. R. Silva <[email protected]>

Reviewed-by: Bjorn Andersson <[email protected]>

Regards,
Bjorn

2017-08-01 08:01:21

by Linus Walleij

Subject: Re: [PATCH] pinctrl: qcom: ssbi-gpio: constify gpio_chip structure

On Tue, Jul 11, 2017 at 8:39 PM, Gustavo A. R. Silva
<[email protected]> wrote:

> This structure is only used to copy into other structure, so declare
> it as const.
>
> This issue was detected using Coccinelle and the following semantic patch:
>
> @r disable optional_qualifier@
> identifier i;
> position p;
> @@
> static struct gpio_chip i@p = { ... };
>
> @ok@
> identifier r.i;
> expression e;
> position p;
> @@
> e = i@p;
>
> @bad@
> position p != {r.p,ok.p};
> identifier r.i;
> struct gpio_chip e;
> @@
> e@i@p
>
> @depends on !bad disable optional_qualifier@
> identifier r.i;
> @@
> static
> +const
> struct gpio_chip i = { ... };
>
> In the following log you can see a significant difference in the code size
> and data segment, hence in the dec segment. This log is the output
> of the size command, before and after the code change:
>
> before:
> text data bss dec hex filename
> 17061 6992 0 24053 5df5 drivers/pinctrl/qcom/pinctrl-ssbi-gpio.o
>
> after:
> text data bss dec hex filename
> 16777 6904 0 23681 5c81 drivers/pinctrl/qcom/pinctrl-ssbi-gpio.o
>
> Signed-off-by: Gustavo A. R. Silva <[email protected]>

Patch applied with Björn's ACK.

Yours,
Linus Walleij