Re: [PATCH] pinctrl: st: constify gpio_chip structure

From: Gustavo A. R. Silva
Date: Wed Jul 12 2017 - 12:52:14 EST


Hi Patrice,

Quoting Patrice CHOTARD <patrice.chotard@xxxxxx>:

Hi Gustavo

On 07/11/2017 08:15 PM, Gustavo A. R. Silva 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
21671 3632 128 25431 6357 drivers/pinctrl/pinctrl-st.o

after:
text data bss dec hex filename
21366 3576 128 25070 61ee drivers/pinctrl/pinctrl-st.o

Signed-off-by: Gustavo A. R. Silva <garsilva@xxxxxxxxxxxxxx>
---
drivers/pinctrl/pinctrl-st.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pinctrl/pinctrl-st.c b/drivers/pinctrl/pinctrl-st.c
index 3ae8066..5d4789d 100644
--- a/drivers/pinctrl/pinctrl-st.c
+++ b/drivers/pinctrl/pinctrl-st.c
@@ -1442,7 +1442,7 @@ static void st_gpio_irqmux_handler(struct irq_desc *desc)
chained_irq_exit(chip, desc);
}

-static struct gpio_chip st_gpio_template = {
+static const struct gpio_chip st_gpio_template = {
.request = gpiochip_generic_request,
.free = gpiochip_generic_free,
.get = st_gpio_get,


Acked-by: Patrice Chotard <patrice.chotard@xxxxxx>

Thanks

Glad to help. :)

Thanks
--
Gustavo A. R. Silva