On Wed, 9 Jan 2008 10:04:42 +0100
Jarek Poplawski [off-list ref] wrote:

On Wed, Jan 09, 2008 at 08:57:53AM +0900, FUJITA Tomonori wrote:
...

quoted

diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
new file mode 100644
index 0000000..495575a
--- /dev/null
+++ b/lib/iommu-helper.c

@@ -0,0 +1,80 @@
+/*
+ * IOMMU helper functions for the free area management
+ */
+
+#include <linux/module.h>
+#include <linux/bitops.h>
+
+static unsigned long find_next_zero_area(unsigned long *map,
+					 unsigned long size,
+					 unsigned long start,
+					 unsigned int nr,
+					 unsigned long align_mask)
+{
+	unsigned long index, end, i;
+again:
+	index = find_next_zero_bit(map, size, start);
+
+	/* Align allocation */
+	index = (index + align_mask) & ~align_mask;
+
+	end = index + nr;
+	if (end >= size)
+		return -1;

This '>=' looks doubtful to me, e.g.:
map points to 0s only,  size = 64, nr = 64,
we get: index = 0; end = 64;
and: return -1 ?!

You are right. I did it only because I didn't want to change the
original code (iommu_range_alloc in arch/powerpc/kernel/iommu.c). I
thought that there might be a mysterious reason for it so I let it
alone since it's tiny loss.

Thanks,