linux-kernel - Re: [PATCH 06/11] irqchip: mips-cpu: Drop unnecessary static

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Date:   Sat, 15 Jul 2017 23:04:45 -0700
From:   Mark D Rustad <mrustad@...il.com>
To:     Julia Lawall <julia.lawall@...6.fr>
Cc:     Thomas Gleixner <tglx@...utronix.de>, keescook@...omium.org,
        kernel-janitors@...r.kernel.org,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <marc.zyngier@....com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 06/11] irqchip: mips-cpu: Drop unnecessary static

> On Jul 15, 2017, at 1:59 PM, Julia Lawall <julia.lawall@...6.fr> wrote:
> 
> On Sat, 15 Jul 2017, Mark D Rustad wrote:
> 
>> 
>>> On Jul 15, 2017, at 1:07 PM, Julia Lawall <Julia.Lawall@...6.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 this is in error like the other one. I believe that the irq_chip structure needs a persistent lifetime.
> 
> I'm not following in this case.  chip is a pointer to a structure, not a
> structure.  Its address is not taken.  irq_set_chip_and_handler that uses
> it below is a fnuction, so it just gets the value.
> 
> julia

Sorry. My mistake. I didn't look quite hard enough at this one.

>> 
>>> 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@...6.fr>
>>> 
>>> ---
>>> These patches are all independent of each other.
>>> 
>>> drivers/irqchip/irq-mips-cpu.c |    2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>> 
>>> diff -u -p a/drivers/irqchip/irq-mips-cpu.c b/drivers/irqchip/irq-mips-cpu.c
>>> --- a/drivers/irqchip/irq-mips-cpu.c
>>> +++ b/drivers/irqchip/irq-mips-cpu.c
>>> @@ -154,7 +154,7 @@ asmlinkage void __weak plat_irq_dispatch
>>> static int mips_cpu_intc_map(struct irq_domain *d, unsigned int irq,
>>> 			     irq_hw_number_t hw)
>>> {
>>> -	static struct irq_chip *chip;
>>> +	struct irq_chip *chip;
>>> 
>>> 	if (hw < 2 && cpu_has_mipsmt) {
>>> 		/* Software interrupts are used for MT/CMT IPI */
>>> 
>> 
>> --
>> Mark Rustad, MRustad@...il.com

--
Mark Rustad, MRustad@...il.com


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