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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 <sebott@linux.vnet.ibm.com> Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
40 lines
1 KiB
C
40 lines
1 KiB
C
/*
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* IOMMU helper functions for the free area management
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*/
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#include <linux/export.h>
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#include <linux/bitmap.h>
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#include <linux/bug.h>
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int iommu_is_span_boundary(unsigned int index, unsigned int nr,
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unsigned long shift,
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unsigned long boundary_size)
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{
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BUG_ON(!is_power_of_2(boundary_size));
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shift = (shift + index) & (boundary_size - 1);
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return shift + nr > boundary_size;
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}
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unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
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unsigned long start, unsigned int nr,
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unsigned long shift, unsigned long boundary_size,
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unsigned long align_mask)
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{
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unsigned long index;
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/* We don't want the last of the limit */
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size -= 1;
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again:
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index = bitmap_find_next_zero_area(map, size, start, nr, align_mask);
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if (index < size) {
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if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
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start = ALIGN(shift + index, boundary_size) - shift;
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goto again;
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}
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bitmap_set(map, index, nr);
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return index;
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}
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return -1;
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}
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EXPORT_SYMBOL(iommu_area_alloc);
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