Paul Mackerras [off-list ref] writes:
On Mon, Jul 09, 2012 at 06:43:38PM +0530, Aneesh Kumar K.V wrote:
quoted
From: "Aneesh Kumar K.V" <redacted>
slice array size and slice mask size depend on PGTABLE_RANGE. We
can't directly include pgtable.h in these header because there is
a circular dependency. So add compile time check for these values.
Some comments below...
quoted
struct slice_mask {
u16 low_slices;
/*
- * This should be derived out of PGTABLE_RANGE. For the current
- * max 64TB, u64 should be ok.
+ * We do this as a union so that we can verify
+ * SLICE_MASK_SIZE against PGTABLE_RANGE
*/
- u64 high_slices;
+ union {
+ u64 high_slices;
+ unsigned char not_used[SLICE_MASK_SIZE];
+ };
Seems ugly to have to have a union just for that. Can't we do
something like BUILD_BUG_ON(sizeof(u64) < SLICE_MASK_SIZE) instead?
Dropped the union from the patch
quoted
@@ -73,7 +73,7 @@ static struct slice_mask slice_range_to_mask(unsigned long start,
unsigned long len)
{
unsigned long end = start + len - 1;
- struct slice_mask ret = { 0, 0 };
+ struct slice_mask ret = { 0, {0} };
Wouldn't { 0 } suffice? Similarly in several places below.
Once i drop the union all these changes can be dropped.
-aneesh