[PATCH 00/11] Drop unnecessary static

[PATCH 00/11] Drop unnecessary static

[Julia Lawall]

These patches fix cases where there is a static on a local variable, but
the variable is initialized before any possible use.  Thus, the static has
no benefit.

---

 drivers/ata/sata_gemini.c                     |    2 +-
 drivers/clk/clk-moxart.c                      |    4 ++--
 drivers/clk/mmp/clk.c                         |    2 +-
 drivers/iio/orientation/hid-sensor-rotation.c |    2 +-
 drivers/irqchip/irq-digicolor.c               |    2 +-
 drivers/irqchip/irq-gic-realview.c            |    2 +-
 drivers/irqchip/irq-mips-cpu.c                |    2 +-
 drivers/mfd/max8925-i2c.c                     |    2 +-
 drivers/mfd/twl4030-irq.c                     |    2 +-
 drivers/mtd/maps/physmap_of_versatile.c       |    2 +-
 drivers/video/fbdev/da8xx-fb.c                |    2 +-
 11 files changed, 12 insertions(+), 12 deletions(-)

[PATCH 07/11] mfd: Drop unnecessary static

[Julia Lawall]

Drop static on a local variable, when the variable is initialized before
any possible use.  Thus, the static has no benefit.

The semantic patch that fixes this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@bad exists@
position p;
identifier x;
type T;
@@
static T x@p;
...
x = <+...x...+>

@@
identifier x;
expression e;
type T;
position p != bad.p;
@@
-static
 T x@p;
 ... when != x
     when strict
?x = e;
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>

---
These patches are all independent of each other.

 drivers/mfd/twl4030-irq.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -u -p a/drivers/mfd/twl4030-irq.c b/drivers/mfd/twl4030-irq.c
--- a/drivers/mfd/twl4030-irq.c
+++ b/drivers/mfd/twl4030-irq.c
@@ -685,7 +685,7 @@ int twl4030_sih_setup(struct device *dev
 
 int twl4030_init_irq(struct device *dev, int irq_num)
 {
-	static struct irq_chip	twl4030_irq_chip;
+	struct irq_chip		twl4030_irq_chip;
 	int			status, i;
 	int			irq_base, irq_end, nr_irqs;
 	struct			device_node *node = dev->of_node;

Re: [PATCH 07/11] mfd: Drop unnecessary static

[Mark D Rustad]

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> On Jul 15, 2017, at 1:07 PM, Julia Lawall <Julia.Lawall@lip6.fr> wrote:
> 
> Drop static on a local variable, when the variable is initialized before
> any possible use.  Thus, the static has no benefit.

I think in this case the use relies on the structure continuing to exist, so a stack object is not an acceptable substitute. Just because it is initialized doesn't mean that it doesn't need a persistent lifetime.

> The semantic patch that fixes this problem is as follows:
> (http://coccinelle.lip6.fr/)
> 
> // <smpl>
> @bad exists@
> position p;
> identifier x;
> type T;
> @@
> static T x@p;
> ...
> x = <+...x...+>
> 
> @@
> identifier x;
> expression e;
> type T;
> position p != bad.p;
> @@
> -static
> T x@p;
> ... when != x
>     when strict
> ?x = e;
> // </smpl>
> 
> Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
> 
> ---
> These patches are all independent of each other.
> 
> drivers/mfd/twl4030-irq.c |    2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff -u -p a/drivers/mfd/twl4030-irq.c b/drivers/mfd/twl4030-irq.c
> --- a/drivers/mfd/twl4030-irq.c
> +++ b/drivers/mfd/twl4030-irq.c
> @@ -685,7 +685,7 @@ int twl4030_sih_setup(struct device *dev
> 
> int twl4030_init_irq(struct device *dev, int irq_num)
> {
> -	static struct irq_chip	twl4030_irq_chip;
> +	struct irq_chip		twl4030_irq_chip;
> 	int			status, i;
> 	int			irq_base, irq_end, nr_irqs;
> 	struct			device_node *node = dev->of_node;

--
Mark Rustad, MRustad@gmail.com


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Re: [PATCH 07/11] mfd: Drop unnecessary static

[Julia Lawall]

On Sat, 15 Jul 2017, Mark D Rustad wrote:

> > On Jul 15, 2017, at 1:07 PM, Julia Lawall <Julia.Lawall@lip6.fr> wrote:
> >
> > Drop static on a local variable, when the variable is initialized before
> > any possible use.  Thus, the static has no benefit.
>
> I think in this case the use relies on the structure continuing to exist, so a stack object is not an acceptable substitute. Just because it is initialized doesn't mean that it doesn't need a persistent lifetime.

OK, I see.  Thanks for the feedback.  I'll extend the rule to ensure that
the address of the variable is not taken.  Ignore this patch in any case.

julia

>
> > The semantic patch that fixes this problem is as follows:
> > (http://coccinelle.lip6.fr/)
> >
> > // <smpl>
> > @bad exists@
> > position p;
> > identifier x;
> > type T;
> > @@
> > static T x@p;
> > ...
> > x = <+...x...+>
> >
> > @@
> > identifier x;
> > expression e;
> > type T;
> > position p != bad.p;
> > @@
> > -static
> > T x@p;
> > ... when != x
> >     when strict
> > ?x = e;
> > // </smpl>
> >
> > Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
> >
> > ---
> > These patches are all independent of each other.
> >
> > drivers/mfd/twl4030-irq.c |    2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff -u -p a/drivers/mfd/twl4030-irq.c b/drivers/mfd/twl4030-irq.c
> > --- a/drivers/mfd/twl4030-irq.c
> > +++ b/drivers/mfd/twl4030-irq.c
> > @@ -685,7 +685,7 @@ int twl4030_sih_setup(struct device *dev
> >
> > int twl4030_init_irq(struct device *dev, int irq_num)
> > {
> > -	static struct irq_chip	twl4030_irq_chip;
> > +	struct irq_chip		twl4030_irq_chip;
> > 	int			status, i;
> > 	int			irq_base, irq_end, nr_irqs;
> > 	struct			device_node *node = dev->of_node;
>
> --
> Mark Rustad, MRustad@gmail.com
>
>

Re: [PATCH 07/11] mfd: Drop unnecessary static

[Pavel Machek]

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Hi!

> > > Drop static on a local variable, when the variable is initialized before
> > > any possible use.  Thus, the static has no benefit.

Actually... it has possible other benefit -- saving stack space. I've
used static for that purpose before. So ... careful with the
automation.

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [PATCH 07/11] mfd: Drop unnecessary static

[Kees Cook]

On Mon, Jul 24, 2017 at 12:20 PM, Pavel Machek <pavel@ucw.cz> wrote:
> Hi!
>
>> > > Drop static on a local variable, when the variable is initialized before
>> > > any possible use.  Thus, the static has no benefit.
>
> Actually... it has possible other benefit -- saving stack space. I've
> used static for that purpose before. So ... careful with the
> automation.

This means any functions like this must not be thread safe, though...

-Kees

-- 
Kees Cook
Pixel Security

Re: [PATCH 07/11] mfd: Drop unnecessary static

[Lee Jones]

On Sat, 15 Jul 2017, Julia Lawall wrote:

> Drop static on a local variable, when the variable is initialized before
> any possible use.  Thus, the static has no benefit.
> 
> The semantic patch that fixes this problem is as follows:
> (http://coccinelle.lip6.fr/)
> 
> // <smpl>
> @bad exists@
> position p;
> identifier x;
> type T;
> @@
> static T x@p;
> ...
> x = <+...x...+>
> 
> @@
> identifier x;
> expression e;
> type T;
> position p != bad.p;
> @@
> -static
>  T x@p;
>  ... when != x
>      when strict
> ?x = e;
> // </smpl>
> 
> Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
> 
> ---
> These patches are all independent of each other.
> 
>  drivers/mfd/twl4030-irq.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Looks like I didn't reply to this patch.

Just to let you know, it has been applied.

> diff -u -p a/drivers/mfd/twl4030-irq.c b/drivers/mfd/twl4030-irq.c
> --- a/drivers/mfd/twl4030-irq.c
> +++ b/drivers/mfd/twl4030-irq.c
> @@ -685,7 +685,7 @@ int twl4030_sih_setup(struct device *dev
>  
>  int twl4030_init_irq(struct device *dev, int irq_num)
>  {
> -	static struct irq_chip	twl4030_irq_chip;
> +	struct irq_chip		twl4030_irq_chip;
>  	int			status, i;
>  	int			irq_base, irq_end, nr_irqs;
>  	struct			device_node *node = dev->of_node;
> 

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [PATCH 00/11] Drop unnecessary static

[Joe Perches]

On Sat, 2017-07-15 at 22:07 +0200, Julia Lawall wrote:
> These patches fix cases where there is a static on a local variable, but
> the variable is initialized before any possible use.  Thus, the static has
> no benefit.

Nice one.

Re: [PATCH 00/11] Drop unnecessary static

[Julia Lawall]

On Sat, 15 Jul 2017, Joe Perches wrote:

> On Sat, 2017-07-15 at 22:07 +0200, Julia Lawall wrote:
> > These patches fix cases where there is a static on a local variable, but
> > the variable is initialized before any possible use.  Thus, the static has
> > no benefit.
>
> Nice one.

Thanks.  It was suggested by Kees Cook a while ago.  There seem to be many
opportunities.

julia