futex: Allow architectures to skip futex_atomic_cmpxchg_inatomic() test

[pandora-kernel.git] / kernel / futex.c

diff --git a/kernel/futex.c b/kernel/futex.c
index 44a1261..5d17e3a 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -157,7 +157,9 @@
  * enqueue.
  */
 
+#ifndef CONFIG_HAVE_FUTEX_CMPXCHG
 int __read_mostly futex_cmpxchg_enabled;
+#endif
 
 /*
  * Futex flags used to encode options to functions and preserve them across
@@ -2843,9 +2845,28 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
        return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
 }
 
-static int __init futex_init(void)
+static void __init futex_detect_cmpxchg(void)
 {
+#ifndef CONFIG_HAVE_FUTEX_CMPXCHG
        u32 curval;
+
+       /*
+        * This will fail and we want it. Some arch implementations do
+        * runtime detection of the futex_atomic_cmpxchg_inatomic()
+        * functionality. We want to know that before we call in any
+        * of the complex code paths. Also we want to prevent
+        * registration of robust lists in that case. NULL is
+        * guaranteed to fault and we get -EFAULT on functional
+        * implementation, the non-functional ones will return
+        * -ENOSYS.
+        */
+       if (cmpxchg_futex_value_locked(&curval, NULL, 0, 0) == -EFAULT)
+               futex_cmpxchg_enabled = 1;
+#endif
+}
+
+static int __init futex_init(void)
+{
        unsigned int futex_shift;
        unsigned long i;
 
@@ -2861,18 +2882,8 @@ static int __init futex_init(void)
                                               &futex_shift, NULL,
                                               futex_hashsize, futex_hashsize);
        futex_hashsize = 1UL << futex_shift;
-       /*
-        * This will fail and we want it. Some arch implementations do
-        * runtime detection of the futex_atomic_cmpxchg_inatomic()
-        * functionality. We want to know that before we call in any
-        * of the complex code paths. Also we want to prevent
-        * registration of robust lists in that case. NULL is
-        * guaranteed to fault and we get -EFAULT on functional
-        * implementation, the non-functional ones will return
-        * -ENOSYS.
-        */
-       if (cmpxchg_futex_value_locked(&curval, NULL, 0, 0) == -EFAULT)
-               futex_cmpxchg_enabled = 1;
+
+       futex_detect_cmpxchg();
 
        for (i = 0; i < futex_hashsize; i++) {
                plist_head_init(&futex_queues[i].chain);