Re: [PATCH v2] cpumask: add cpumask_var_t documentation

[Thiago Farina]

On Thu, Apr 28, 2011 at 12:27 PM, KOSAKI Motohiro
<kosaki.motohiro@xxxxxxxxxxxxxx> wrote:
> cpumask_var_t has one nortable difference against cpumask_t.
> This patch adds the explanation.
>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> ---
> Âinclude/linux/cpumask.h | Â 14 ++++++++++++++
> Â1 files changed, 14 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> index 1e40dd0..471c98a 100644
> --- a/include/linux/cpumask.h
> +++ b/include/linux/cpumask.h
> @@ -617,6 +617,20 @@ static inline size_t cpumask_size(void)
> Â* Â Â Â ... use 'tmpmask' like a normal struct cpumask * ...
> Â*
> Â* Â Â free_cpumask_var(tmpmask);
> + *
> + *
> + * However, one notable exception is there. cpumask_var_t is allocated
> + * only nr_cpu_ids bits

Maybe, instead of "is allocated only", "allocates only" ?


> (in the other hand, real cpumask_t always has
> + * NR_CPUS bits). therefore You don't have to dereference cpumask_var_t.

s/therefore You/Therefore you/ ?

> + *
> + * Â Â cpumask_var_t tmpmask;
> + * Â Â if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
> + * Â Â Â Â Â Â return -ENOMEM;
> + *
> + * Â Â var = *tmpmask;
> + *
> + * This code makes NR_CPUS length memcopy and bring memroy corruption.

/s/memroy/memory

You are saying that I should not use this code? I'm confused, could
you explain a little bit?

> + * You have to use cpumask_copy() instead.
> Â*/

I don't get this. :(


> Â#ifdef CONFIG_CPUMASK_OFFSTACK
> Âtypedef struct cpumask *cpumask_var_t;
> --
> 1.7.3.1
>
>
>
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