Hi Rasmus,
On 04/27/2015 09:45 AM, Rasmus Villemoes wrote:
> On Mon, Apr 27 2015, Daniel Wagner <daniel.wag...@bmw-carit.de> wrote:
>
>> static int cmp_32(const void *a, const void *b)
>> {
>> return (int) (*(u32 *)a - *(u32 *)b);
>> }
>>
>> static int cmp_64(const void *a, const void *b)
>> {
>> return (int) (*(u64 *)a - *(u64 *)b);
>> }
>>
>
> Please [1] don't [2] do [3] this [4].
>
> [1] acbbe6fbb240a927ee1f5994f04d31267d422215 kcmp: fix standard comparison bug
>
> [2] ef17af2a817db97d42dd2ec0a425231748e23dbc fs: nfsd: Fix signedness bug in
> compare_blob
>
> [3] ddbc22e27e672b6b180757ea1d7f8481dbb88128 fs/hfs/catalog.c: fix comparison
> bug in hfs_cat_keycmp
>
> [4] 72392ed0eb6fde96826cb9d66bd4f50a7ba61450 kernfs: Fix kernfs_name_compare
>
> (sorry for not actually looking at the patch - this just triggered one
> of my pet peeves).
Thanks for the pointers. I see, even the simplest stuff is not that
simple. I'll keep an eye open for this one :)
In this case though it is not so bad. You are looking at test code. I
used that one to test the performance of the patch not the correctness
since there is the boot-time regression test for the sorting.
The main part of this path is a new u64 swap function:
+static void u64_swap(void *a, void *b, int size)
+{
+ u64 t = *(u64 *)a;
+ *(u64 *)a = *(u64 *)b;
+ *(u64 *)b = t;
+}
+
cheers,
daniel
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