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mm/mempolicy.c:offset_il_node() document and clarify 

This code was pretty obscure and was relying upon obscure side-effects
of next_node(-1, ...) and was relying upon NUMA_NO_NODE being equal to
-1.

Clean that all up and document the function's intent.

Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrew Morton 2016-05-19 17:11:43 -07:00 committed by Linus Torvalds
parent 54f18d3526
commit fee83b3aba
1 changed files with 11 additions and 9 deletions
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20
mm/mempolicy.c
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@ -1758,23 +1758,25 @@ unsigned int mempolicy_slab_node(void)
}
}
/* Do static interleaving for a VMA with known offset. */
/*
* Do static interleaving for a VMA with known offset @n. Returns the n'th
* node in pol->v.nodes (starting from n=0), wrapping around if n exceeds the
* number of present nodes.
*/
static unsigned offset_il_node(struct mempolicy *pol,
struct vm_area_struct *vma, unsigned long off)
struct vm_area_struct *vma, unsigned long n)
{
unsigned nnodes = nodes_weight(pol->v.nodes);
unsigned target;
int c;
int nid = NUMA_NO_NODE;
int i;
int nid;
if (!nnodes)
return numa_node_id();
target = (unsigned int)off % nnodes;
c = 0;
do {
target = (unsigned int)n % nnodes;
nid = first_node(pol->v.nodes);
for (i = 0; i < target; i++)
nid = next_node(nid, pol->v.nodes);
c++;
} while (c <= target);
return nid;
}