Commit f003a1f1 authored by Sebastian Ott's avatar Sebastian Ott Committed by Linus Torvalds

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@schleppiSigned-off-by: default avatarSebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: default avatarGerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4cad35a7
...@@ -29,8 +29,7 @@ unsigned long iommu_area_alloc(unsigned long *map, unsigned long size, ...@@ -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); index = bitmap_find_next_zero_area(map, size, start, nr, align_mask);
if (index < size) { if (index < size) {
if (iommu_is_span_boundary(index, nr, shift, boundary_size)) { if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
/* we could do more effectively */ start = ALIGN(shift + index, boundary_size) - shift;
start = index + 1;
goto again; goto again;
} }
bitmap_set(map, index, nr); bitmap_set(map, index, nr);
......
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