[PATCH 1/1 v2] powerpc: hugetlb pgtable cache access cleanup

[PATCH 1/1 v2] powerpc: hugetlb pgtable cache access cleanup

[Jon Tollefson]

It was suggested by Andrew that using a macro that made an array
look like a function call made it harder to understand the code.
Cleaned up use of macro.  We now reference the pgtable_cache array
directly instead of using a macro.  


Signed-off-by: Jon Tollefson <kniht@linux.vnet.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
---

 arch/powerpc/mm/hugetlbpage.c |   22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff -puN arch/powerpc/mm/hugetlbpage.c~powerpc-hugetlb-pgtable-cache-access-cleanup arch/powerpc/mm/hugetlbpage.c
--- a/arch/powerpc/mm/hugetlbpage.c~powerpc-hugetlb-pgtable-cache-access-cleanup
+++ a/arch/powerpc/mm/hugetlbpage.c
@@ -53,8 +53,7 @@ unsigned int mmu_huge_psizes[MMU_PAGE_CO

 /* Subtract one from array size because we don't need a cache for 4K since
  * is not a huge page size */
-#define huge_pgtable_cache(psize)	(pgtable_cache[HUGEPTE_CACHE_NUM \
-							+ psize-1])
+#define HUGE_PGTABLE_INDEX(psize)	(HUGEPTE_CACHE_NUM + psize - 1)
 #define HUGEPTE_CACHE_NAME(psize)	(huge_pgtable_cache_name[psize])

 static const char *huge_pgtable_cache_name[MMU_PAGE_COUNT] = {
@@ -113,7 +112,7 @@ static inline pte_t *hugepte_offset(huge
 static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
 			   unsigned long address, unsigned int psize)
 {
-	pte_t *new = kmem_cache_zalloc(huge_pgtable_cache(psize),
+	pte_t *new = kmem_cache_zalloc(pgtable_cache[HUGE_PGTABLE_INDEX(psize)],
 				      GFP_KERNEL|__GFP_REPEAT);

 	if (! new)
@@ -121,7 +120,7 @@ static int __hugepte_alloc(struct mm_str

 	spin_lock(&mm->page_table_lock);
 	if (!hugepd_none(*hpdp))
-		kmem_cache_free(huge_pgtable_cache(psize), new);
+		kmem_cache_free(pgtable_cache[HUGE_PGTABLE_INDEX(psize)], new);
 	else
 		hpdp->pd = (unsigned long)new | HUGEPD_OK;
 	spin_unlock(&mm->page_table_lock);
@@ -760,13 +759,14 @@ static int __init hugetlbpage_init(void)

 	for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
 		if (mmu_huge_psizes[psize]) {
-			huge_pgtable_cache(psize) = kmem_cache_create(
-						HUGEPTE_CACHE_NAME(psize),
-						HUGEPTE_TABLE_SIZE(psize),
-						HUGEPTE_TABLE_SIZE(psize),
-						0,
-						NULL);
-			if (!huge_pgtable_cache(psize))
+			pgtable_cache[HUGE_PGTABLE_INDEX(psize)] =
+				kmem_cache_create(
+					HUGEPTE_CACHE_NAME(psize),
+					HUGEPTE_TABLE_SIZE(psize),
+					HUGEPTE_TABLE_SIZE(psize),
+					0,
+					NULL);
+			if (!pgtable_cache[HUGE_PGTABLE_INDEX(psize)])
 				panic("hugetlbpage_init(): could not create %s"\
 				      "\n", HUGEPTE_CACHE_NAME(psize));
 		}
_

Re: [PATCH 1/1 v2] powerpc: hugetlb pgtable cache access cleanup

[Andrew Morton]

On Thu, 30 Oct 2008 17:03:57 -0500
Jon Tollefson <kniht@linux.vnet.ibm.com> wrote:

> It was suggested by Andrew that using a macro that made an array
> look like a function call made it harder to understand the code.
> Cleaned up use of macro.  We now reference the pgtable_cache array
> directly instead of using a macro.  

I felt compelled to apply this.  See http://en.wikipedia.org/wiki/Sunk_costs
to see why I am an irrational actor.