From f003a1f182bb821f13775338a4bf8711830f927a Mon Sep 17 00:00:00 2001 From: Sebastian Ott Date: Tue, 2 Aug 2016 14:04:13 -0700 Subject: [PATCH] lib/iommu-helper: skip to next segment When a large enough area in the iommu bitmap is found but would span a boundary we continue the search starting from the next bit position. For large allocations this can lead to several useless invocations of bitmap_find_next_zero_area() and iommu_is_span_boundary(). Continue the search from the start of the next segment (which is the next bit position such that we'll not cross the same segment boundary again). Link: http://lkml.kernel.org/r/alpine.LFD.2.20.1606081910070.3211@schleppi Signed-off-by: Sebastian Ott Reviewed-by: Gerald Schaefer Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/iommu-helper.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c index c27e269210c4..a816f3a80625 100644 --- a/lib/iommu-helper.c +++ b/lib/iommu-helper.c @@ -29,8 +29,7 @@ unsigned long iommu_area_alloc(unsigned long *map, unsigned long size, index = bitmap_find_next_zero_area(map, size, start, nr, align_mask); if (index < size) { if (iommu_is_span_boundary(index, nr, shift, boundary_size)) { - /* we could do more effectively */ - start = index + 1; + start = ALIGN(shift + index, boundary_size) - shift; goto again; } bitmap_set(map, index, nr); -- GitLab