| Message ID | 1500149266-32357-8-git-send-email-Julia.Lawall@lip6.fr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> 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
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 > > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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.
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
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; >
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;
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(-) -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html