[PATCH 1/2] mm: define USE_SPLIT_PTLOCKS rather than repeating expression

From: Jeremy Fitzhardinge
Date: Tue Sep 09 2008 - 18:43:36 EST


Define USE_SPLIT_PTLOCKS as a constant expression rather than repeating
"NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS" all over the place.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
arch/x86/xen/mmu.c | 2 +-
include/linux/mm.h | 6 +++---
include/linux/mm_types.h | 10 ++++++----
include/linux/sched.h | 6 +++---
4 files changed, 13 insertions(+), 11 deletions(-)

===================================================================
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -805,7 +805,7 @@
{
spinlock_t *ptl = NULL;

-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#if USE_SPLIT_PTLOCKS
ptl = __pte_lockptr(page);
spin_lock_nest_lock(ptl, &mm->page_table_lock);
#endif
===================================================================
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -914,7 +914,7 @@
}
#endif /* CONFIG_MMU && !__ARCH_HAS_4LEVEL_HACK */

-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#if USE_SPLIT_PTLOCKS
/*
* We tuck a spinlock to guard each pagetable page into its struct page,
* at page->private, with BUILD_BUG_ON to make sure that this will not
@@ -927,14 +927,14 @@
} while (0)
#define pte_lock_deinit(page) ((page)->mapping = NULL)
#define pte_lockptr(mm, pmd) ({(void)(mm); __pte_lockptr(pmd_page(*(pmd)));})
-#else
+#else /* !USE_SPLIT_PTLOCKS */
/*
* We use mm->page_table_lock to guard all pagetable pages of the mm.
*/
#define pte_lock_init(page) do {} while (0)
#define pte_lock_deinit(page) do {} while (0)
#define pte_lockptr(mm, pmd) ({(void)(pmd); &(mm)->page_table_lock;})
-#endif /* NR_CPUS < CONFIG_SPLIT_PTLOCK_CPUS */
+#endif /* USE_SPLIT_PTLOCKS */

static inline void pgtable_page_ctor(struct page *page)
{
===================================================================
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -21,11 +21,13 @@

struct address_space;

-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#define USE_SPLIT_PTLOCKS (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS)
+
+#if USE_SPLIT_PTLOCKS
typedef atomic_long_t mm_counter_t;
-#else /* NR_CPUS < CONFIG_SPLIT_PTLOCK_CPUS */
+#else /* !USE_SPLIT_PTLOCKS */
typedef unsigned long mm_counter_t;
-#endif /* NR_CPUS < CONFIG_SPLIT_PTLOCK_CPUS */
+#endif /* !USE_SPLIT_PTLOCKS */

/*
* Each physical page in the system has a struct page associated with
@@ -65,7 +67,7 @@
* see PAGE_MAPPING_ANON below.
*/
};
-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#if USE_SPLIT_PTLOCKS
spinlock_t ptl;
#endif
struct kmem_cache *slab; /* SLUB: Pointer to slab */
===================================================================
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -352,7 +352,7 @@
extern void arch_unmap_area(struct mm_struct *, unsigned long);
extern void arch_unmap_area_topdown(struct mm_struct *, unsigned long);

-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+#if USE_SPLIT_PTLOCKS
/*
* The mm counters are not protected by its page_table_lock,
* so must be incremented atomically.
@@ -363,7 +363,7 @@
#define inc_mm_counter(mm, member) atomic_long_inc(&(mm)->_##member)
#define dec_mm_counter(mm, member) atomic_long_dec(&(mm)->_##member)

-#else /* NR_CPUS < CONFIG_SPLIT_PTLOCK_CPUS */
+#else /* !USE_SPLIT_PTLOCKS */
/*
* The mm counters are protected by its page_table_lock,
* so can be incremented directly.
@@ -374,7 +374,7 @@
#define inc_mm_counter(mm, member) (mm)->_##member++
#define dec_mm_counter(mm, member) (mm)->_##member--

-#endif /* NR_CPUS < CONFIG_SPLIT_PTLOCK_CPUS */
+#endif /* !USE_SPLIT_PTLOCKS */

#define get_mm_rss(mm) \
(get_mm_counter(mm, file_rss) + get_mm_counter(mm, anon_rss))


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