On May 12, 2014, at 8:36 AM, Ben Pfaff <b...@nicira.com> wrote:
> On Sun, May 11, 2014 at 11:55:01PM -0700, Jarno Rajahalme wrote:
>> Array splicing was broken when multiple elements were being moved,
>> resulting in the priority order being mixed. This came up when the
>> highest priority rule from a subtable was removed and the subtable
>> needed to be moved down the priority list by more than one position.
>>
>> Signed-off-by: Jarno Rajahalme <jrajaha...@nicira.com>
>
> Can you explain what this function does? I feel like it should be
> obvious (I mean, clearly it's reordering the array), but in fact I'm
> having trouble puzzling it out.
>
It moves elements starting from ‘start’ and ending before ‘end’ to ‘to’. This
is the same as swapping the places of items [to,start) and [start,end), when to
< start. I implemented shifting to one direction only, so in the buggy case the
arguments are shifted like this: to = start, start = end and end = (old) to.
The loop moves elements one by one, moving the items [to, start) forward by
one, and moving the (old) ‘start' element to ‘to’. I forgot to advance the ‘to’
at each round...
Jarno
>> diff --git a/lib/classifier.c b/lib/classifier.c
>> index a9046cd..aef57bb 100644
>> --- a/lib/classifier.c
>> +++ b/lib/classifier.c
>> @@ -224,12 +224,14 @@ cls_subtable_cache_splice(struct cls_subtable_entry
>> *to,
>> to = start; start = end; end = temp;
>> }
>> if (to < start) {
>> + /* Move elements [start, end) to (to) one by one. */
>> while (start != end) {
>> struct cls_subtable_entry temp = *start;
>>
>> + /* Shift array by one, making space for the element at 'temp'.
>> */
>> memmove(to + 1, to, (start - to) * sizeof *to);
>> *to = temp;
>> - start++;
>> + start++; to++;
>> }
>> } /* Else nothing to be done. */
>> }
>> --
>> 1.7.10.4
>>
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