From fee83b3aba4b7ddb0cb1497a04ddebcaa43f236e Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Thu, 19 May 2016 17:11:43 -0700 Subject: [PATCH] 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 Cc: Xishi Qiu Cc: Joonsoo Kim Cc: David Rientjes Cc: Naoya Horiguchi Cc: Laura Abbott Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mempolicy.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 8d369ce..7f80ebc 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -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; } -- 2.7.4