2007-08-13 13:09:57

by Surya Prabhakar N

Subject: [KJ] replacing kmalloc with kzalloc in io_apic.c

Hi,
Replacing kmalloc with kzalloc and cleaning up memset in
arch/i386/kernel/io_apic.c


Signed-off-by: Surya Prabhakar <[email protected]>
---

diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
index 4b8a8da..1329615 100644
--- a/arch/i386/kernel/io_apic.c
+++ b/arch/i386/kernel/io_apic.c
@@ -690,14 +690,12 @@ static int __init balanced_irq_init(void)
physical_balance = 1;

for_each_online_cpu(i) {
- irq_cpu_data[i].irq_delta = kmalloc(sizeof(unsigned long) * NR_IRQS, GFP_KERNEL);
- irq_cpu_data[i].last_irq = kmalloc(sizeof(unsigned long) * NR_IRQS, GFP_KERNEL);
+ irq_cpu_data[i].irq_delta = kzalloc(sizeof(unsigned long) * NR_IRQS, GFP_KERNEL);
+ irq_cpu_data[i].last_irq = kzalloc(sizeof(unsigned long) * NR_IRQS, GFP_KERNEL);
if (irq_cpu_data[i].irq_delta == NULL || irq_cpu_data[i].last_irq == NULL) {
printk(KERN_ERR "balanced_irq_init: out of memory");
goto failed;
}
- memset(irq_cpu_data[i].irq_delta,0,sizeof(unsigned long) * NR_IRQS);
- memset(irq_cpu_data[i].last_irq,0,sizeof(unsigned long) * NR_IRQS);
}

printk(KERN_INFO "Starting balanced_irq\n");



thanks
surya.

2007-08-13 15:30:41

by Mariusz Kozlowski

Subject: Re: [KJ] replacing kmalloc with kzalloc in io_apic.c

> Hi,
> Replacing kmalloc with kzalloc and cleaning up memset in
> arch/i386/kernel/io_apic.c
>
>
> Signed-off-by: Surya Prabhakar <[email protected]>
> ---
>
> diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
> index 4b8a8da..1329615 100644
> --- a/arch/i386/kernel/io_apic.c
> +++ b/arch/i386/kernel/io_apic.c
> @@ -690,14 +690,12 @@ static int __init balanced_irq_init(void)
> physical_balance = 1;
>
> for_each_online_cpu(i) {
> - irq_cpu_data[i].irq_delta = kmalloc(sizeof(unsigned long) * NR_IRQS,
> GFP_KERNEL); - irq_cpu_data[i].last_irq = kmalloc(sizeof(unsigned long) *
> NR_IRQS, GFP_KERNEL); + irq_cpu_data[i].irq_delta =
> kzalloc(sizeof(unsigned long) * NR_IRQS, GFP_KERNEL);
> + irq_cpu_data[i].last_irq = kzalloc(sizeof(unsigned long) * NR_IRQS,
> GFP_KERNEL); if (irq_cpu_data[i].irq_delta == NULL ||
> irq_cpu_data[i].last_irq == NULL) { printk(KERN_ERR "balanced_irq_init: out
> of memory");
> goto failed;
> }
> - memset(irq_cpu_data[i].irq_delta,0,sizeof(unsigned long) * NR_IRQS);
> - memset(irq_cpu_data[i].last_irq,0,sizeof(unsigned long) * NR_IRQS);
> }
>
> printk(KERN_INFO "Starting balanced_irq\n");

How about using kcalloc here?

i.e.
...
... = kcalloc(NR_IRQS, sizeof(unsigned long), GFP_KERNEL);
...

Regards,

Mariusz

2007-08-13 16:48:43

by Robert P. J. Day

Subject: Re: [KJ] replacing kmalloc with kzalloc in io_apic.c

On Mon, 13 Aug 2007, Mariusz Kozlowski wrote:

> > Hi,
> > Replacing kmalloc with kzalloc and cleaning up memset in
> > arch/i386/kernel/io_apic.c
> >
> >
> > Signed-off-by: Surya Prabhakar <[email protected]>
> > ---
> >
> > diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
> > index 4b8a8da..1329615 100644
> > --- a/arch/i386/kernel/io_apic.c
> > +++ b/arch/i386/kernel/io_apic.c
> > @@ -690,14 +690,12 @@ static int __init balanced_irq_init(void)
> > physical_balance = 1;
> >
> > for_each_online_cpu(i) {
> > - irq_cpu_data[i].irq_delta = kmalloc(sizeof(unsigned long) * NR_IRQS,
> > GFP_KERNEL); - irq_cpu_data[i].last_irq = kmalloc(sizeof(unsigned long) *
> > NR_IRQS, GFP_KERNEL); + irq_cpu_data[i].irq_delta =
> > kzalloc(sizeof(unsigned long) * NR_IRQS, GFP_KERNEL);
> > + irq_cpu_data[i].last_irq = kzalloc(sizeof(unsigned long) * NR_IRQS,
> > GFP_KERNEL); if (irq_cpu_data[i].irq_delta == NULL ||
> > irq_cpu_data[i].last_irq == NULL) { printk(KERN_ERR "balanced_irq_init: out
> > of memory");
> > goto failed;
> > }
> > - memset(irq_cpu_data[i].irq_delta,0,sizeof(unsigned long) * NR_IRQS);
> > - memset(irq_cpu_data[i].last_irq,0,sizeof(unsigned long) * NR_IRQS);
> > }
> >
> > printk(KERN_INFO "Starting balanced_irq\n");
>
> How about using kcalloc here?
>
> i.e.
> ...
> ... = kcalloc(NR_IRQS, sizeof(unsigned long), GFP_KERNEL);
> ...

from my days submitting numerous patches of this type, i can recall
that in cases like the above, it's a judgment call -- use kzalloc to
get the zeroing, or use kcalloc to get the array-flavoured behaviour.
what a shame you can't have both at the same time.

rday
--
========================================================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA

http://fsdev.net/wiki/index.php?title=Main_Page
========================================================================

2007-08-13 17:31:12

by Roland Dreier

Subject: Re: [KJ] replacing kmalloc with kzalloc in io_apic.c

> from my days submitting numerous patches of this type, i can recall
> that in cases like the above, it's a judgment call -- use kzalloc to
> get the zeroing, or use kcalloc to get the array-flavoured behaviour.
> what a shame you can't have both at the same time.

kcalloc() zeros memory just like standard calloc() in userspace.

As <linux/slab.h> says:

* kcalloc - allocate memory for an array. The memory is set to zero.

2007-08-13 17:37:43

by Robert P. J. Day

Subject: Re: [KJ] replacing kmalloc with kzalloc in io_apic.c

On Mon, 13 Aug 2007, Roland Dreier wrote:

> > from my days submitting numerous patches of this type, i can recall
> > that in cases like the above, it's a judgment call -- use kzalloc to
> > get the zeroing, or use kcalloc to get the array-flavoured behaviour.
> > what a shame you can't have both at the same time.
>
> kcalloc() zeros memory just like standard calloc() in userspace.
>
> As <linux/slab.h> says:
>
> * kcalloc - allocate memory for an array. The memory is set to zero.

oops. quite right, my bad.

rday
--
========================================================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA

http://fsdev.net/wiki/index.php?title=Main_Page
========================================================================