Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab...

[firefly-linux-kernel-4.4.55.git] / kernel / futex.c

diff --git a/kernel/futex.c b/kernel/futex.c
index 08ec814ad9d2fe95ae4303085cb1967265bd3758..6801b3751a95cd0933463fc38039cb77d6ced705 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
@@ -1450,6 +1452,7 @@ retry:
        hb2 = hash_futex(&key2);
 
 retry_private:
+       hb_waiters_inc(hb2);
        double_lock_hb(hb1, hb2);
 
        if (likely(cmpval != NULL)) {
@@ -1459,6 +1462,7 @@ retry_private:
 
                if (unlikely(ret)) {
                        double_unlock_hb(hb1, hb2);
+                       hb_waiters_dec(hb2);
 
                        ret = get_user(curval, uaddr1);
                        if (ret)
@@ -1508,6 +1512,7 @@ retry_private:
                        break;
                case -EFAULT:
                        double_unlock_hb(hb1, hb2);
+                       hb_waiters_dec(hb2);
                        put_futex_key(&key2);
                        put_futex_key(&key1);
                        ret = fault_in_user_writeable(uaddr2);
@@ -1517,6 +1522,7 @@ retry_private:
                case -EAGAIN:
                        /* The owner was exiting, try again. */
                        double_unlock_hb(hb1, hb2);
+                       hb_waiters_dec(hb2);
                        put_futex_key(&key2);
                        put_futex_key(&key1);
                        cond_resched();
@@ -1592,6 +1598,7 @@ retry_private:
 
 out_unlock:
        double_unlock_hb(hb1, hb2);
+       hb_waiters_dec(hb2);
 
        /*
         * drop_futex_key_refs() must be called outside the spinlocks. During
@@ -2875,9 +2882,28 @@ 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;
 
@@ -2893,18 +2919,8 @@ 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++) {
                atomic_set(&futex_queues[i].waiters, 0);