On Mon, Jun 09, 2008 at 11:28:00AM -0700, Christoph Lameter wrote:
> On Mon, 9 Jun 2008, Russ Anderson wrote:
>
> > -#define PAGE_FLAGS (1 << PG_lru | 1 << PG_private | 1 << PG_locked | \
> > +#define PAGE_FLAGS_BASE (1 << PG_lru | 1 << PG_private | 1 << PG_locked | \
> > 1 << PG_buddy | 1 << PG_writeback | \
> > 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active)
> > +
> > +#ifdef CONFIG_PAGEFLAGS_EXTENDED
> > +PAGEFLAG(MemError, memerror)
> > +#define PAGE_FLAGS (PAGE_FLAGS_BASE | 1UL << PG_memerror)
> > +#else
> > +PAGEFLAG_FALSE(MemError)
> > +#define PAGE_FLAGS (PAGE_FLAGS_BASE)
> > +#endif
>
> Hmmmm... That doesnt look nice. It would be good if we had some definition
> that allows the simple oring with a flag mask. That mask should be
> zero if the flag is always false.
>
> #ifdef CONFIG_PAGEFLAGS_EXTENDED
> PAGEFLAG(MemError, memerror)
> #define MemError_mask (1 << PG_memerror)
> #else
> PAGEFLAG_FALSE(MemError)
> #define MemError_mask 0
> #endif
>
> #define PAGE_FLAGS (PAGE_FLAGS_BASE | MemError_mask)
>
> Maybe we could have the PAGEFLAG and the PAGEFLAG_FALSE macros generate
> these definitions?
Does this look better?
Index: linus/include/linux/page-flags.h
===================================================================
--- linus.orig/include/linux/page-flags.h 2008-06-09 13:48:10.072171477 -0500
+++ linus/include/linux/page-flags.h 2008-06-09 15:58:27.957729371 -0500
@@ -84,6 +84,7 @@ enum pageflags {
PG_private, /* If pagecache, has fs-private data */
PG_writeback, /* Page is under writeback */
#ifdef CONFIG_PAGEFLAGS_EXTENDED
+ PG_memerror, /* Page has a physical memory error */
PG_head, /* A head page */
PG_tail, /* A tail page */
#else
@@ -132,15 +133,21 @@ static inline int TestSetPage##uname(str
static inline int TestClearPage##uname(struct page *page) \
{ return test_and_clear_bit(PG_##lname, &page->flags); }
+#define PAGEFLAGMASK(uname, lname) \
+static inline int PAGEMASK_##uname(void) \
+ { return (1 << PG_##lname); }
#define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
- SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname)
+ SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname) \
+ PAGEFLAGMASK(uname, lname)
#define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
__SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname)
#define PAGEFLAG_FALSE(uname) \
static inline int Page##uname(struct page *page) \
+ { return 0; } \
+static inline int PAGEMASK_##uname(void) \
{ return 0; }
#define TESTSCFLAG(uname, lname) \
@@ -307,9 +314,16 @@ static inline void __ClearPageTail(struc
#endif /* !PAGEFLAGS_EXTENDED */
+#ifdef CONFIG_PAGEFLAGS_EXTENDED
+PAGEFLAG(MemError, memerror)
+#else
+PAGEFLAG_FALSE(MemError)
+#endif
+
#define PAGE_FLAGS (1 << PG_lru | 1 << PG_private | 1 << PG_locked | \
1 << PG_buddy | 1 << PG_writeback | \
- 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active)
+ 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active) |\
+ PAGEMASK_MemError()
/*
* Flags checked in bad_page(). Pages on the free list should not have
--
Russ Anderson, OS RAS/Partitioning Project Lead
SGI - Silicon Graphics Inc rja@xxxxxxx
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