[PATCH] mm: pagefault_{disable,enable}()
Introduce pagefault_{disable,enable}() and use these where previously we did
manual preempt increments/decrements to make the pagefault handler do the
atomic thing.
Currently they still rely on the increased preempt count, but do not rely on
the disabled preemption, this might go away in the future.
(NOTE: the extra barrier() in pagefault_disable might fix some holes on
machines which have too many registers for their own good)
[heiko.carstens@de.ibm.com: s390 fix]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Nick Piggin <npiggin@suse.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/futex.c b/kernel/futex.c
index 93ef30b..af7b81c 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -282,9 +282,9 @@
{
int ret;
- inc_preempt_count();
+ pagefault_disable();
ret = __copy_from_user_inatomic(dest, from, sizeof(u32));
- dec_preempt_count();
+ pagefault_enable();
return ret ? -EFAULT : 0;
}
@@ -585,9 +585,9 @@
if (!(uval & FUTEX_OWNER_DIED)) {
newval = FUTEX_WAITERS | new_owner->pid;
- inc_preempt_count();
+ pagefault_disable();
curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval);
- dec_preempt_count();
+ pagefault_enable();
if (curval == -EFAULT)
return -EFAULT;
if (curval != uval)
@@ -618,9 +618,9 @@
* There is no waiter, so we unlock the futex. The owner died
* bit has not to be preserved here. We are the owner:
*/
- inc_preempt_count();
+ pagefault_disable();
oldval = futex_atomic_cmpxchg_inatomic(uaddr, uval, 0);
- dec_preempt_count();
+ pagefault_enable();
if (oldval == -EFAULT)
return oldval;
@@ -1158,9 +1158,9 @@
*/
newval = current->pid;
- inc_preempt_count();
+ pagefault_disable();
curval = futex_atomic_cmpxchg_inatomic(uaddr, 0, newval);
- dec_preempt_count();
+ pagefault_enable();
if (unlikely(curval == -EFAULT))
goto uaddr_faulted;
@@ -1183,9 +1183,9 @@
uval = curval;
newval = uval | FUTEX_WAITERS;
- inc_preempt_count();
+ pagefault_disable();
curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval);
- dec_preempt_count();
+ pagefault_enable();
if (unlikely(curval == -EFAULT))
goto uaddr_faulted;
@@ -1215,10 +1215,10 @@
newval = current->pid |
FUTEX_OWNER_DIED | FUTEX_WAITERS;
- inc_preempt_count();
+ pagefault_disable();
curval = futex_atomic_cmpxchg_inatomic(uaddr,
uval, newval);
- dec_preempt_count();
+ pagefault_enable();
if (unlikely(curval == -EFAULT))
goto uaddr_faulted;
@@ -1390,9 +1390,9 @@
* anyone else up:
*/
if (!(uval & FUTEX_OWNER_DIED)) {
- inc_preempt_count();
+ pagefault_disable();
uval = futex_atomic_cmpxchg_inatomic(uaddr, current->pid, 0);
- dec_preempt_count();
+ pagefault_enable();
}
if (unlikely(uval == -EFAULT))