GitHub-Mirror/linux-bl808
2
0
Fork 0
mirror of https://github.com/Fishwaldo/linux-bl808.git synced 2025-06-17 20:25:19 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

powerpc/mm: Lockless get_user_pages_fast() for 64-bit (v3)

Browse source 
Implement lockless get_user_pages_fast for 64-bit powerpc.

Page table existence is guaranteed with RCU, and speculative page references
are used to take a reference to the pages without having a prior existence
guarantee on them.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Nick Piggin 2008-07-30 15:23:13 +10:00 • committed by Benjamin Herrenschmidt
parent 7d2a175b9b
commit ce0ad7f095
5 changed files with 310 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

23
include/linux/pagemap.h
View file

@ -143,6 +143,29 @@ static inline int page_cache_get_speculative(struct page *page)
return 1;
}
/*
* Same as above, but add instead of inc (could just be merged)
*/
static inline int page_cache_add_speculative(struct page *page, int count)
{
VM_BUG_ON(in_interrupt());
#if !defined(CONFIG_SMP) && defined(CONFIG_CLASSIC_RCU)
# ifdef CONFIG_PREEMPT
VM_BUG_ON(!in_atomic());
# endif
VM_BUG_ON(page_count(page) == 0);
atomic_add(count, &page->_count);
#else
if (unlikely(!atomic_add_unless(&page->_count, count, 0)))
return 0;
#endif
VM_BUG_ON(PageCompound(page) && page != compound_head(page));
return 1;
}
static inline int page_freeze_refs(struct page *page, int count)
{
return likely(atomic_cmpxchg(&page->_count, count, 0) == count);