[llvmlinux] Fwd: [PATCH] slab: Remove unnecessary __builtin_constant_p()

[Tinti]

This is great! One patch less (if accepted).


On Wed, Apr 17, 2013 at 4:25 PM, Behan Webster <behanw at converseincode.com>wrote:

> Steve has submitted a patch to remove the __builtin_constant_p issue. :)
>
> Behan
>
> Sent from my Mobile Computer which is also a phone
>
> Begin forwarded message:
>
> *From:* Steven Rostedt <rostedt at goodmis.org>
> *Date:* 17 April, 2013 12:09:36 PM PDT
> *To:* LKML <linux-kernel at vger.kernel.org>, linux-mm at kvack.org
> *Cc:* Christoph Lameter <cl at linux.com>, Behan Webster <
> behanw at converseincode.com>,  Andrew Morton <akpm at linux-foundation.org>
> *Subject:* *[PATCH] slab: Remove unnecessary __builtin_constant_p()*
>
> The slab.c code has a size check macro that checks the size of the
> following structs:
>
> struct arraycache_init
> struct kmem_list3
>
> The index_of() function that takes the sizeof() of the above two structs
> and does an unnecessary __builtin_constant_p() on that. As sizeof() will
> always end up being a constant making this always be true. The code is
> not incorrect, but it just adds added complexity, and confuses users and
> wastes the time of reviewers of the code, who spends time trying to
> figure out why the builtin_constant_p() was used.
>
> This patch is just a clean up that makes the index_of() code a little
> bit less complex.
>
> Signed-off-by: Steven Rostedt <rostedt at goodmis.org>
>
> diff --git a/mm/slab.c b/mm/slab.c
> index 856e4a1..6047900 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -325,9 +325,7 @@ static void cache_reap(struct work_struct *unused);
>  static __always_inline int index_of(const size_t size)
> {
>    extern void __bad_size(void);
> -
> -    if (__builtin_constant_p(size)) {
> -        int i = 0;
> +    int i = 0;
>
> #define CACHE(x) \
>    if (size <=x) \
> @@ -336,9 +334,7 @@ static __always_inline int index_of(const size_t size)
>        i++;
>  #include <linux/kmalloc_sizes.h>
> #undef CACHE
> -        __bad_size();
> -    } else
> -        __bad_size();
> +    __bad_size();
>     return 0;
> }
>
>
>
>
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-- 
Simplicity is the ultimate sophistication
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