Re: [PATCH v2 3/4] iommu/iova: Extend rbtree node caching

[Robin Murphy <robin.murphy@arm.com>]

On 19/09/17 10:42, Leizhen (ThunderTown) wrote:
[...]
>>>>     static void
>>>>   __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova
>>>> *free)
>>>>   {
>>>>       struct iova *cached_iova;
>>>> -    struct rb_node *curr;
>>>> +    struct rb_node **curr = NULL;
>>>>   -    if (!iovad->cached32_node)
>>>> -        return;
>>>> -    curr = iovad->cached32_node;
>>>> -    cached_iova = rb_entry(curr, struct iova, node);
> 
> -----------------------------
>>>> +    if (free->pfn_hi < iovad->dma_32bit_pfn)
>>>> +        curr = &iovad->cached32_node;
>>>> +    if (!curr)
>>>> +        curr = &iovad->cached_node;
>>
>> +	if (!*curr)
>> +		return;
> Is it necessary for us to try the following adjustment?
> +	if (free->pfn_hi < iovad->dma_32bit_pfn)
> +		curr = &iovad->cached32_node;
> +	else
> +		curr = &iovad->cached_node;
> +
> +	if (!*curr) {
> +		*curr = rb_next(&free->node);
> +		return;
> +	}

Yeah, I spotted that this looked a bit wonky after I posted it. It's
already cleaned up in v3, which I'll be posting shortly after I write up
some cover letters.

Thanks,
Robin.