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@xxxxxxxxxxxxxxxxx> >>> --- >>> 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
