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SubjectRe: [PATCH] mm/hugetlb: hide nr_nodes in the internal of for_each_node_mask_to_[alloc|free]
On Tue, Jul 14, 2020 at 11:22:03AM +0200, Vlastimil Babka wrote:
>On 7/14/20 11:13 AM, Vlastimil Babka wrote:
>> On 7/14/20 9:34 AM, Wei Yang wrote:
>>> The second parameter of for_each_node_mask_to_[alloc|free] is a loop
>>> variant, which is not used outside of loop iteration.
>>>
>>> Let's hide this.
>>>
>>> Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
>>> ---
>>> mm/hugetlb.c | 38 ++++++++++++++++++++------------------
>>> 1 file changed, 20 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>>> index 57ece74e3aae..9c3d15fb317e 100644
>>> --- a/mm/hugetlb.c
>>> +++ b/mm/hugetlb.c
>>> @@ -1196,17 +1196,19 @@ static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
>>> return nid;
>>> }
>>>
>>> -#define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask) \
>>> - for (nr_nodes = nodes_weight(*mask); \
>>> - nr_nodes > 0 && \
>>> +#define for_each_node_mask_to_alloc(hs, node, mask) \
>>> + int __nr_nodes; \
>>> + for (__nr_nodes = nodes_weight(*mask); \
>>
>> The problem with this is that if I use the macro twice in the same block, this
>> will redefine __nr_nodes and fail to compile, no?
>> In that case it's better to avoid setting up this trap, IMHO.
>
>Ah, and it will also generate the following warning, if the use of for_each*
>macro is not the first thing after variable declarations, but there's another
>statement before:
>
>warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
>
>Instead we should switch to C99 and declare it as "for (int __nr_nodes" :P

Thanks, I haven't notice the problem you mentioned.

Let me fix this.

--
Wei Yang
Help you, Help me

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