From: Wei Yang <richard.weiyang@linux.alibaba.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>,
mike.kravetz@oracle.com, akpm@linux-foundation.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/hugetlb: hide nr_nodes in the internal of for_each_node_mask_to_[alloc|free]
Date: Tue, 14 Jul 2020 17:57:13 +0800 [thread overview]
Message-ID: <20200714095713.GA86690@L-31X9LVDL-1304.local> (raw)
In-Reply-To: <807a1e32-926b-2882-740b-6484b8dca2b6@suse.cz>
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
Hmm... I tried what you suggested, but compiler complains.
'for' loop initial declarations are only allowed in C99 or C11 mode
--
Wei Yang
Help you, Help me
next prev parent reply other threads:[~2020-07-14 9:57 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-14 7:34 [PATCH] mm/hugetlb: hide nr_nodes in the internal of for_each_node_mask_to_[alloc|free] Wei Yang
2020-07-14 8:37 ` Pankaj Gupta
2020-07-14 9:13 ` Vlastimil Babka
2020-07-14 9:22 ` Vlastimil Babka
2020-07-14 9:50 ` Wei Yang
2020-07-14 9:57 ` Wei Yang [this message]
2020-07-14 10:02 ` Vlastimil Babka
2020-07-14 21:12 ` Mike Kravetz
2020-07-15 3:46 ` Wei Yang
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