tracing: Fix function graph trace_pipe to properly display failed entries

[safe/jmp/linux-2.6] / kernel / futex.c

diff --git a/kernel/futex.c b/kernel/futex.c
index c3bb2fc..fb65e82 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -150,7 +150,8 @@ static struct futex_hash_bucket *hash_futex(union futex_key *key)
  */
 static inline int match_futex(union futex_key *key1, union futex_key *key2)
 {
-       return (key1->both.word == key2->both.word
+       return (key1 && key2
+               && key1->both.word == key2->both.word
                && key1->both.ptr == key2->both.ptr
                && key1->both.offset == key2->both.offset);
 }
@@ -1028,7 +1029,6 @@ static inline
 void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
                           struct futex_hash_bucket *hb)
 {
-       drop_futex_key_refs(&q->key);
        get_futex_key_refs(key);
        q->key = *key;
 
@@ -1226,6 +1226,7 @@ retry_private:
                 */
                if (ret == 1) {
                        WARN_ON(pi_state);
+                       drop_count++;
                        task_count++;
                        ret = get_futex_value_locked(&curval2, uaddr2);
                        if (!ret)
@@ -1304,6 +1305,7 @@ retry_private:
                        if (ret == 1) {
                                /* We got the lock. */
                                requeue_pi_wake_futex(this, &key2, hb2);
+                               drop_count++;
                                continue;
                        } else if (ret) {
                                /* -EDEADLK */
@@ -1656,6 +1658,12 @@ out:
 static void futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q *q,
                                struct hrtimer_sleeper *timeout)
 {
+       /*
+        * The task state is guaranteed to be set before another task can
+        * wake it. set_current_state() is implemented using set_mb() and
+        * queue_me() calls spin_unlock() upon completion, both serializing
+        * access to the hash list and forcing another memory barrier.
+        */
        set_current_state(TASK_INTERRUPTIBLE);
        queue_me(q, hb);
 
@@ -1785,6 +1793,7 @@ static int futex_wait(u32 __user *uaddr, int fshared,
                                             current->timer_slack_ns);
        }
 
+retry:
        /* Prepare to wait on uaddr. */
        ret = futex_wait_setup(uaddr, val, fshared, &q, &hb);
        if (ret)
@@ -1802,9 +1811,14 @@ static int futex_wait(u32 __user *uaddr, int fshared,
                goto out_put_key;
 
        /*
-        * We expect signal_pending(current), but another thread may
-        * have handled it for us already.
+        * We expect signal_pending(current), but we might be the
+        * victim of a spurious wakeup as well.
         */
+       if (!signal_pending(current)) {
+               put_futex_key(fshared, &q.key);
+               goto retry;
+       }
+
        ret = -ERESTARTSYS;
        if (!abs_time)
                goto out_put_key;
@@ -2112,9 +2126,11 @@ int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb,
                 */
                plist_del(&q->list, &q->list.plist);
 
+               /* Handle spurious wakeups gracefully */
+               ret = -EWOULDBLOCK;
                if (timeout && !timeout->task)
                        ret = -ETIMEDOUT;
-               else
+               else if (signal_pending(current))
                        ret = -ERESTARTNOINTR;
        }
        return ret;