Re: [minor fix] radixtree: regulate tag get return value

[Andrew Morton]

On Sun, 4 Jun 2006 16:45:48 +0800
Wu Fengguang <wfg@xxxxxxxxxxxxxxxx> wrote:

> Andrew, this small patch makes the radixtree tester program from
>         http://www.zip.com.au/~akpm/linux/patches/stuff/rtth.tar.gz
> run OK, with the latest radix tree code in linux-2.6.17-rc5-mm2.
> 
> It regulates the return value to 0/1 for functions
> radix_tree_tag_get() and radix_tree_tagged().
> 

Well yes.  But it slows down the kernel.  It would be better to fix rtth.

> ---
> 
> --- linux.orig/lib/radix-tree.c
> +++ linux/lib/radix-tree.c
> @@ -156,7 +156,7 @@ static inline void tag_clear(struct radi
>  static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
>  		int offset)
>  {
> -	return test_bit(offset, node->tags[tag]);
> +	return !! test_bit(offset, node->tags[tag]);
>  }

test_bit() is (sadly) defined to return 0 or 1.  Did this really make a difference?

>  static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
> @@ -177,7 +177,7 @@ static inline void root_tag_clear_all(st
>  
>  static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
>  {
> -	return root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
> +	return !! (root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT)));
>  }
>  

-
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