[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>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/s390/lib/uaccess_std.c b/arch/s390/lib/uaccess_std.c
index 2d549ed2e113..bbaca66fa293 100644
--- a/arch/s390/lib/uaccess_std.c
+++ b/arch/s390/lib/uaccess_std.c
@@ -11,7 +11,7 @@
 
 #include <linux/errno.h>
 #include <linux/mm.h>
-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
 #include <asm/futex.h>
 
 #ifndef __s390x__
@@ -258,7 +258,7 @@ int futex_atomic_op(int op, int __user *uaddr, int oparg, int *old)
 {
         int oldval = 0, newval, ret;
 
-        inc_preempt_count();
+        pagefault_disable();
 
         switch (op) {
         case FUTEX_OP_SET:
@@ -284,7 +284,7 @@ int futex_atomic_op(int op, int __user *uaddr, int oparg, int *old)
         default:
                 ret = -ENOSYS;
         }
-        dec_preempt_count();
+        pagefault_enable();
         *old = oldval;
         return ret;
 }