On Wed, 2014-12-10 at 17:32 +0100, Rasmus Villemoes wrote:
> Relying on the sign (after casting to int) of the difference of two
> quantities for comparison is usually wrong. For example, should a-b
> turn out to be 2^31, the return value of cmp(a,b) is -2^31; but that
> would also be the return value from cmp(b, a). So a compares less than
> b and b compares less than a. One can also easily find three values
> a,b,c such that a compares less than b, b compares less than c, but a
> does not compare less than c.
> 

Looks good for me. Thank you for the fix.

Reviewed-by: Vyacheslav Dubeyko <sl...@dubeyko.com>

Thanks,
Vyacheslav Dubeyko.

> Signed-off-by: Rasmus Villemoes <li...@rasmusvillemoes.dk>
> ---
>  fs/hfs/catalog.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/hfs/catalog.c b/fs/hfs/catalog.c
> index ff0316b925a5..db458ee3a546 100644
> --- a/fs/hfs/catalog.c
> +++ b/fs/hfs/catalog.c
> @@ -162,14 +162,16 @@ err2:
>   */
>  int hfs_cat_keycmp(const btree_key *key1, const btree_key *key2)
>  {
> -     int retval;
> +     __be32 k1p, k2p;
>  
> -     retval = be32_to_cpu(key1->cat.ParID) - be32_to_cpu(key2->cat.ParID);
> -     if (!retval)
> -             retval = hfs_strcmp(key1->cat.CName.name, key1->cat.CName.len,
> -                                 key2->cat.CName.name, key2->cat.CName.len);
> +     k1p = key1->cat.ParID;
> +     k2p = key2->cat.ParID;
>  
> -     return retval;
> +     if (k1p != k2p)
> +             return be32_to_cpu(k1p) < be32_to_cpu(k2p) ? -1 : 1;
> +
> +     return hfs_strcmp(key1->cat.CName.name, key1->cat.CName.len,
> +                       key2->cat.CName.name, key2->cat.CName.len);
>  }
>  
>  /* Try to get a catalog entry for given catalog id */


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Reply via email to