1 files changed, 283 insertions, 241 deletions

diff --git a/kernel/futex.c b/kernel/futex.c
index 6a3a5fa1526d..fe28dc282eae 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -69,6 +69,14 @@ int __read_mostly futex_cmpxchg_enabled;
 #define FUTEX_HASHBITS (CONFIG_BASE_SMALL ? 4 : 8)
 
 /*
+ * Futex flags used to encode options to functions and preserve them across
+ * restarts.
+ */
+#define FLAGS_SHARED            0x01
+#define FLAGS_CLOCKRT           0x02
+#define FLAGS_HAS_TIMEOUT       0x04
+
+/*
  * Priority Inheritance state:
  */
 struct futex_pi_state {
@@ -91,6 +99,7 @@ struct futex_pi_state {
 
 /**
  * struct futex_q - The hashed futex queue entry, one per waiting task
+ * @list:               priority-sorted list of tasks waiting on this futex
  * @task:               the task waiting on the futex
  * @lock_ptr:           the hash bucket lock
  * @key:                the key the futex is hashed on
@@ -104,7 +113,7 @@ struct futex_pi_state {
  *
  * A futex_q has a woken state, just like tasks have TASK_RUNNING.
  * It is considered woken when plist_node_empty(&q->list) || q->lock_ptr == 0.
- * The order of wakup is always to make the first condition true, then
+ * The order of wakeup is always to make the first condition true, then
  * the second.
  *
  * PI futexes are typically woken before they are removed from the hash list via
@@ -122,6 +131,12 @@ struct futex_q {
         u32 bitset;
 };
 
+static const struct futex_q futex_q_init = {
+        /* list gets initialized in queue_me()*/
+        .key = FUTEX_KEY_INIT,
+        .bitset = FUTEX_BITSET_MATCH_ANY
+};
+
 /*
  * Hash buckets are shared by all the futex_keys that hash to the same
  * location.  Each key may have multiple futex_q structures, one for each task
@@ -168,7 +183,7 @@ static void get_futex_key_refs(union futex_key *key)
 
         switch (key->both.offset & (FUT_OFF_INODE|FUT_OFF_MMSHARED)) {
         case FUT_OFF_INODE:
-                atomic_inc(&key->shared.inode->i_count);
+                ihold(key->shared.inode);
                 break;
         case FUT_OFF_MMSHARED:
                 atomic_inc(&key->private.mm->mm_count);
@@ -218,7 +233,7 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key)
 {
         unsigned long address = (unsigned long)uaddr;
         struct mm_struct *mm = current->mm;
-        struct page *page;
+        struct page *page, *page_head;
         int err;
 
         /*
@@ -250,11 +265,46 @@ again:
         if (err < 0)
                 return err;
 
-        page = compound_head(page);
-        lock_page(page);
-        if (!page->mapping) {
-                unlock_page(page);
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+        page_head = page;
+        if (unlikely(PageTail(page))) {
                 put_page(page);
+                /* serialize against __split_huge_page_splitting() */
+                local_irq_disable();
+                if (likely(__get_user_pages_fast(address, 1, 1, &page) == 1)) {
+                        page_head = compound_head(page);
+                        /*
+                         * page_head is valid pointer but we must pin
+                         * it before taking the PG_lock and/or
+                         * PG_compound_lock. The moment we re-enable
+                         * irqs __split_huge_page_splitting() can
+                         * return and the head page can be freed from
+                         * under us. We can't take the PG_lock and/or
+                         * PG_compound_lock on a page that could be
+                         * freed from under us.
+                         */
+                        if (page != page_head) {
+                                get_page(page_head);
+                                put_page(page);
+                        }
+                        local_irq_enable();
+                } else {
+                        local_irq_enable();
+                        goto again;
+                }
+        }
+#else
+        page_head = compound_head(page);
+        if (page != page_head) {
+                get_page(page_head);
+                put_page(page);
+        }
+#endif
+
+        lock_page(page_head);
+        if (!page_head->mapping) {
+                unlock_page(page_head);
+                put_page(page_head);
                 goto again;
         }
 
@@ -265,25 +315,24 @@ again:
          * it's a read-only handle, it's expected that futexes attach to
          * the object not the particular process.
          */
-        if (PageAnon(page)) {
+        if (PageAnon(page_head)) {
                 key->both.offset |= FUT_OFF_MMSHARED; /* ref taken on mm */
                 key->private.mm = mm;
                 key->private.address = address;
         } else {
                 key->both.offset |= FUT_OFF_INODE; /* inode-based key */
-                key->shared.inode = page->mapping->host;
-                key->shared.pgoff = page->index;
+                key->shared.inode = page_head->mapping->host;
+                key->shared.pgoff = page_head->index;
         }
 
         get_futex_key_refs(key);
 
-        unlock_page(page);
-        put_page(page);
+        unlock_page(page_head);
+        put_page(page_head);
         return 0;
 }
 
-static inline
-void put_futex_key(int fshared, union futex_key *key)
+static inline void put_futex_key(union futex_key *key)
 {
         drop_futex_key_refs(key);
 }
@@ -295,7 +344,7 @@ void put_futex_key(int fshared, union futex_key *key)
  * Slow path to fixup the fault we just took in the atomic write
  * access to @uaddr.
  *
- * We have no generic implementation of a non destructive write to the
+ * We have no generic implementation of a non-destructive write to the
  * user address. We know that we faulted in the atomic pagefault
  * disabled section so we can as well avoid the #PF overhead by
  * calling get_user_pages() right away.
@@ -332,15 +381,16 @@ static struct futex_q *futex_top_waiter(struct futex_hash_bucket *hb,
         return NULL;
 }
 
-static u32 cmpxchg_futex_value_locked(u32 __user *uaddr, u32 uval, u32 newval)
+static int cmpxchg_futex_value_locked(u32 *curval, u32 __user *uaddr,
+                                      u32 uval, u32 newval)
 {
-        u32 curval;
+        int ret;
 
         pagefault_disable();
-        curval = futex_atomic_cmpxchg_inatomic(uaddr, uval, newval);
+        ret = futex_atomic_cmpxchg_inatomic(curval, uaddr, uval, newval);
         pagefault_enable();
 
-        return curval;
+        return ret;
 }
 
 static int get_futex_value_locked(u32 *dest, u32 __user *from)
@@ -515,7 +565,7 @@ lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
                          */
                         pi_state = this->pi_state;
                         /*
-                         * Userspace might have messed up non PI and PI futexes
+                         * Userspace might have messed up non-PI and PI futexes
                          */
                         if (unlikely(!pi_state))
                                 return -EINVAL;
@@ -625,7 +675,7 @@ static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb,
                                 struct task_struct *task, int set_waiters)
 {
         int lock_taken, ret, ownerdied = 0;
-        u32 uval, newval, curval;
+        u32 uval, newval, curval, vpid = task_pid_vnr(task);
 
 retry:
         ret = lock_taken = 0;
@@ -635,19 +685,17 @@ retry:
          * (by doing a 0 -> TID atomic cmpxchg), while holding all
          * the locks. It will most likely not succeed.
          */
-        newval = task_pid_vnr(task);
+        newval = vpid;
         if (set_waiters)
                 newval |= FUTEX_WAITERS;
 
-        curval = cmpxchg_futex_value_locked(uaddr, 0, newval);
-
-        if (unlikely(curval == -EFAULT))
+        if (unlikely(cmpxchg_futex_value_locked(&curval, uaddr, 0, newval)))
                 return -EFAULT;
 
         /*
          * Detect deadlocks.
          */
-        if ((unlikely((curval & FUTEX_TID_MASK) == task_pid_vnr(task))))
+        if ((unlikely((curval & FUTEX_TID_MASK) == vpid)))
                 return -EDEADLK;
 
         /*
@@ -674,14 +722,12 @@ retry:
          */
         if (unlikely(ownerdied || !(curval & FUTEX_TID_MASK))) {
                 /* Keep the OWNER_DIED bit */
-                newval = (curval & ~FUTEX_TID_MASK) | task_pid_vnr(task);
+                newval = (curval & ~FUTEX_TID_MASK) | vpid;
                 ownerdied = 0;
                 lock_taken = 1;
         }
 
-        curval = cmpxchg_futex_value_locked(uaddr, uval, newval);
-
-        if (unlikely(curval == -EFAULT))
+        if (unlikely(cmpxchg_futex_value_locked(&curval, uaddr, uval, newval)))
                 return -EFAULT;
         if (unlikely(curval != uval))
                 goto retry;
@@ -726,6 +772,24 @@ retry:
         return ret;
 }
 
+/**
+ * __unqueue_futex() - Remove the futex_q from its futex_hash_bucket
+ * @q:  The futex_q to unqueue
+ *
+ * The q->lock_ptr must not be NULL and must be held by the caller.
+ */
+static void __unqueue_futex(struct futex_q *q)
+{
+        struct futex_hash_bucket *hb;
+
+        if (WARN_ON_SMP(!q->lock_ptr || !spin_is_locked(q->lock_ptr))
+            || WARN_ON(plist_node_empty(&q->list)))
+                return;
+
+        hb = container_of(q->lock_ptr, struct futex_hash_bucket, lock);
+        plist_del(&q->list, &hb->chain);
+}
+
 /*
  * The hash bucket lock must be held when this is called.
  * Afterwards, the futex_q must not be accessed.
@@ -736,14 +800,14 @@ static void wake_futex(struct futex_q *q)
 
         /*
          * We set q->lock_ptr = NULL _before_ we wake up the task. If
-         * a non futex wake up happens on another CPU then the task
-         * might exit and p would dereference a non existing task
+         * a non-futex wake up happens on another CPU then the task
+         * might exit and p would dereference a non-existing task
          * struct. Prevent this by holding a reference on p across the
          * wake up.
          */
         get_task_struct(p);
 
-        plist_del(&q->list, &q->list.plist);
+        __unqueue_futex(q);
         /*
          * The waiting task can free the futex_q as soon as
          * q->lock_ptr = NULL is written, without taking any locks. A
@@ -777,10 +841,9 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this)
         new_owner = rt_mutex_next_owner(&pi_state->pi_mutex);
 
         /*
-         * This happens when we have stolen the lock and the original
-         * pending owner did not enqueue itself back on the rt_mutex.
-         * Thats not a tragedy. We know that way, that a lock waiter
-         * is on the fly. We make the futex_q waiter the pending owner.
+         * It is possible that the next waiter (the one that brought
+         * this owner to the kernel) timed out and is no longer
+         * waiting on the lock.
          */
         if (!new_owner)
                 new_owner = this->task;
@@ -795,9 +858,7 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this)
 
                 newval = FUTEX_WAITERS | task_pid_vnr(new_owner);
 
-                curval = cmpxchg_futex_value_locked(uaddr, uval, newval);
-
-                if (curval == -EFAULT)
+                if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval))
                         ret = -EFAULT;
                 else if (curval != uval)
                         ret = -EINVAL;
@@ -832,10 +893,8 @@ static int unlock_futex_pi(u32 __user *uaddr, u32 uval)
          * There is no waiter, so we unlock the futex. The owner died
          * bit has not to be preserved here. We are the owner:
          */
-        oldval = cmpxchg_futex_value_locked(uaddr, uval, 0);
-
-        if (oldval == -EFAULT)
-                return oldval;
+        if (cmpxchg_futex_value_locked(&oldval, uaddr, uval, 0))
+                return -EFAULT;
         if (oldval != uval)
                 return -EAGAIN;
 
@@ -869,7 +928,8 @@ double_unlock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2)
 /*
  * Wake up waiters matching bitset queued on this futex (uaddr).
  */
-static int futex_wake(u32 __user *uaddr, int fshared, int nr_wake, u32 bitset)
+static int
+futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset)
 {
         struct futex_hash_bucket *hb;
         struct futex_q *this, *next;
@@ -880,7 +940,7 @@ static int futex_wake(u32 __user *uaddr, int fshared, int nr_wake, u32 bitset)
         if (!bitset)
                 return -EINVAL;
 
-        ret = get_futex_key(uaddr, fshared, &key);
+        ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &key);
         if (unlikely(ret != 0))
                 goto out;
 
@@ -906,7 +966,7 @@ static int futex_wake(u32 __user *uaddr, int fshared, int nr_wake, u32 bitset)
         }
 
         spin_unlock(&hb->lock);
-        put_futex_key(fshared, &key);
+        put_futex_key(&key);
 out:
         return ret;
 }
@@ -916,7 +976,7 @@ out:
  * to this virtual address:
  */
 static int
-futex_wake_op(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
+futex_wake_op(u32 __user *uaddr1, unsigned int flags, u32 __user *uaddr2,
               int nr_wake, int nr_wake2, int op)
 {
         union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT;
@@ -926,10 +986,10 @@ futex_wake_op(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
         int ret, op_ret;
 
 retry:
-        ret = get_futex_key(uaddr1, fshared, &key1);
+        ret = get_futex_key(uaddr1, flags & FLAGS_SHARED, &key1);
         if (unlikely(ret != 0))
                 goto out;
-        ret = get_futex_key(uaddr2, fshared, &key2);
+        ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2);
         if (unlikely(ret != 0))
                 goto out_put_key1;
 
@@ -961,11 +1021,11 @@ retry_private:
                 if (ret)
                         goto out_put_keys;
 
-                if (!fshared)
+                if (!(flags & FLAGS_SHARED))
                         goto retry_private;
 
-                put_futex_key(fshared, &key2);
-                put_futex_key(fshared, &key1);
+                put_futex_key(&key2);
+                put_futex_key(&key1);
                 goto retry;
         }
 
@@ -995,9 +1055,9 @@ retry_private:
 
         double_unlock_hb(hb1, hb2);
 out_put_keys:
-        put_futex_key(fshared, &key2);
+        put_futex_key(&key2);
 out_put_key1:
-        put_futex_key(fshared, &key1);
+        put_futex_key(&key1);
 out:
         return ret;
 }
@@ -1022,9 +1082,6 @@ void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1,
                 plist_del(&q->list, &hb1->chain);
                 plist_add(&q->list, &hb2->chain);
                 q->lock_ptr = &hb2->lock;
-#ifdef CONFIG_DEBUG_PI_LIST
-                q->list.plist.spinlock = &hb2->lock;
-#endif
         }
         get_futex_key_refs(key2);
         q->key = *key2;
@@ -1051,16 +1108,12 @@ void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
         get_futex_key_refs(key);
         q->key = *key;
 
-        WARN_ON(plist_node_empty(&q->list));
-        plist_del(&q->list, &q->list.plist);
+        __unqueue_futex(q);
 
         WARN_ON(!q->rt_waiter);
         q->rt_waiter = NULL;
 
         q->lock_ptr = &hb->lock;
-#ifdef CONFIG_DEBUG_PI_LIST
-        q->list.plist.spinlock = &hb->lock;
-#endif
 
         wake_up_state(q->task, TASK_NORMAL);
 }
@@ -1131,12 +1184,14 @@ static int futex_proxy_trylock_atomic(u32 __user *pifutex,
 
 /**
  * futex_requeue() - Requeue waiters from uaddr1 to uaddr2
- * uaddr1:      source futex user address
- * uaddr2:      target futex user address
- * nr_wake:     number of waiters to wake (must be 1 for requeue_pi)
- * nr_requeue:  number of waiters to requeue (0-INT_MAX)
- * requeue_pi:  if we are attempting to requeue from a non-pi futex to a
- *              pi futex (pi to pi requeue is not supported)
+ * @uaddr1:     source futex user address
+ * @flags:      futex flags (FLAGS_SHARED, etc.)
+ * @uaddr2:     target futex user address
+ * @nr_wake:    number of waiters to wake (must be 1 for requeue_pi)
+ * @nr_requeue: number of waiters to requeue (0-INT_MAX)
+ * @cmpval:     @uaddr1 expected value (or %NULL)
+ * @requeue_pi: if we are attempting to requeue from a non-pi futex to a
+ *              pi futex (pi to pi requeue is not supported)
  *
  * Requeue waiters on uaddr1 to uaddr2. In the requeue_pi case, try to acquire
  * uaddr2 atomically on behalf of the top waiter.
@@ -1145,9 +1200,9 @@ static int futex_proxy_trylock_atomic(u32 __user *pifutex,
  * >=0 - on success, the number of tasks requeued or woken
  *  <0 - on error
  */
-static int futex_requeue(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
-                         int nr_wake, int nr_requeue, u32 *cmpval,
-                         int requeue_pi)
+static int futex_requeue(u32 __user *uaddr1, unsigned int flags,
+                         u32 __user *uaddr2, int nr_wake, int nr_requeue,
+                         u32 *cmpval, int requeue_pi)
 {
         union futex_key key1 = FUTEX_KEY_INIT, key2 = FUTEX_KEY_INIT;
         int drop_count = 0, task_count = 0, ret;
@@ -1188,10 +1243,10 @@ retry:
                 pi_state = NULL;
         }
 
-        ret = get_futex_key(uaddr1, fshared, &key1);
+        ret = get_futex_key(uaddr1, flags & FLAGS_SHARED, &key1);
         if (unlikely(ret != 0))
                 goto out;
-        ret = get_futex_key(uaddr2, fshared, &key2);
+        ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2);
         if (unlikely(ret != 0))
                 goto out_put_key1;
 
@@ -1213,11 +1268,11 @@ retry_private:
                         if (ret)
                                 goto out_put_keys;
 
-                        if (!fshared)
+                        if (!(flags & FLAGS_SHARED))
                                 goto retry_private;
 
-                        put_futex_key(fshared, &key2);
-                        put_futex_key(fshared, &key1);
+                        put_futex_key(&key2);
+                        put_futex_key(&key1);
                         goto retry;
                 }
                 if (curval != *cmpval) {
@@ -1257,8 +1312,8 @@ retry_private:
                         break;
                 case -EFAULT:
                         double_unlock_hb(hb1, hb2);
-                        put_futex_key(fshared, &key2);
-                        put_futex_key(fshared, &key1);
+                        put_futex_key(&key2);
+                        put_futex_key(&key1);
                         ret = fault_in_user_writeable(uaddr2);
                         if (!ret)
                                 goto retry;
@@ -1266,8 +1321,8 @@ retry_private:
                 case -EAGAIN:
                         /* The owner was exiting, try again. */
                         double_unlock_hb(hb1, hb2);
-                        put_futex_key(fshared, &key2);
-                        put_futex_key(fshared, &key1);
+                        put_futex_key(&key2);
+                        put_futex_key(&key1);
                         cond_resched();
                         goto retry;
                 default:
@@ -1349,9 +1404,9 @@ out_unlock:
                 drop_futex_key_refs(&key1);
 
 out_put_keys:
-        put_futex_key(fshared, &key2);
+        put_futex_key(&key2);
 out_put_key1:
-        put_futex_key(fshared, &key1);
+        put_futex_key(&key1);
 out:
         if (pi_state != NULL)
                 free_pi_state(pi_state);
@@ -1360,10 +1415,10 @@ out:
 
 /* The key must be already stored in q->key. */
 static inline struct futex_hash_bucket *queue_lock(struct futex_q *q)
+        __acquires(&hb->lock)
 {
         struct futex_hash_bucket *hb;
 
-        get_futex_key_refs(&q->key);
         hb = hash_futex(&q->key);
         q->lock_ptr = &hb->lock;
 
@@ -1373,9 +1428,9 @@ static inline struct futex_hash_bucket *queue_lock(struct futex_q *q)
 
 static inline void
 queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb)
+        __releases(&hb->lock)
 {
         spin_unlock(&hb->lock);
-        drop_futex_key_refs(&q->key);
 }
 
 /**
@@ -1391,6 +1446,7 @@ queue_unlock(struct futex_q *q, struct futex_hash_bucket *hb)
  * an example).
  */
 static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
+        __releases(&hb->lock)
 {
         int prio;
 
@@ -1405,9 +1461,6 @@ static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
         prio = min(current->normal_prio, MAX_RT_PRIO);
 
         plist_node_init(&q->list, prio);
-#ifdef CONFIG_DEBUG_PI_LIST
-        q->list.plist.spinlock = &hb->lock;
-#endif
         plist_add(&q->list, &hb->chain);
         q->task = current;
         spin_unlock(&hb->lock);
@@ -1452,8 +1505,7 @@ retry:
                         spin_unlock(lock_ptr);
                         goto retry;
                 }
-                WARN_ON(plist_node_empty(&q->list));
-                plist_del(&q->list, &q->list.plist);
+                __unqueue_futex(q);
 
                 BUG_ON(q->pi_state);
 
@@ -1471,17 +1523,15 @@ retry:
  * and dropped here.
  */
 static void unqueue_me_pi(struct futex_q *q)
+        __releases(q->lock_ptr)
 {
-        WARN_ON(plist_node_empty(&q->list));
-        plist_del(&q->list, &q->list.plist);
+        __unqueue_futex(q);
 
         BUG_ON(!q->pi_state);
         free_pi_state(q->pi_state);
         q->pi_state = NULL;
 
         spin_unlock(q->lock_ptr);
-
-        drop_futex_key_refs(&q->key);
 }
 
 /*
@@ -1491,7 +1541,7 @@ static void unqueue_me_pi(struct futex_q *q)
  * private futexes.
  */
 static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
-                                struct task_struct *newowner, int fshared)
+                                struct task_struct *newowner)
 {
         u32 newtid = task_pid_vnr(newowner) | FUTEX_WAITERS;
         struct futex_pi_state *pi_state = q->pi_state;
@@ -1505,10 +1555,10 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
 
         /*
          * We are here either because we stole the rtmutex from the
-         * pending owner or we are the pending owner which failed to
-         * get the rtmutex. We have to replace the pending owner TID
-         * in the user space variable. This must be atomic as we have
-         * to preserve the owner died bit here.
+         * previous highest priority waiter or we are the highest priority
+         * waiter but failed to get the rtmutex the first time.
+         * We have to replace the newowner TID in the user space variable.
+         * This must be atomic as we have to preserve the owner died bit here.
          *
          * Note: We write the user space value _before_ changing the pi_state
          * because we can fault here. Imagine swapped out pages or a fork
@@ -1527,9 +1577,7 @@ retry:
         while (1) {
                 newval = (uval & FUTEX_OWNER_DIED) | newtid;
 
-                curval = cmpxchg_futex_value_locked(uaddr, uval, newval);
-
-                if (curval == -EFAULT)
+                if (cmpxchg_futex_value_locked(&curval, uaddr, uval, newval))
                         goto handle_fault;
                 if (curval == uval)
                         break;
@@ -1557,8 +1605,8 @@ retry:
 
         /*
          * To handle the page fault we need to drop the hash bucket
-         * lock here. That gives the other task (either the pending
-         * owner itself or the task which stole the rtmutex) the
+         * lock here. That gives the other task (either the highest priority
+         * waiter itself or the task which stole the rtmutex) the
          * chance to try the fixup of the pi_state. So once we are
          * back from handling the fault we need to check the pi_state
          * after reacquiring the hash bucket lock and before trying to
@@ -1584,20 +1632,11 @@ handle_fault:
         goto retry;
 }
 
-/*
- * In case we must use restart_block to restart a futex_wait,
- * we encode in the 'flags' shared capability
- */
-#define FLAGS_SHARED            0x01
-#define FLAGS_CLOCKRT           0x02
-#define FLAGS_HAS_TIMEOUT       0x04
-
 static long futex_wait_restart(struct restart_block *restart);
 
 /**
  * fixup_owner() - Post lock pi_state and corner case management
  * @uaddr:      user address of the futex
- * @fshared:    whether the futex is shared (1) or not (0)
  * @q:          futex_q (contains pi_state and access to the rt_mutex)
  * @locked:     if the attempt to take the rt_mutex succeeded (1) or not (0)
  *
@@ -1610,8 +1649,7 @@ static long futex_wait_restart(struct restart_block *restart);
  *  0 - success, lock not taken
  * <0 - on error (-EFAULT)
  */
-static int fixup_owner(u32 __user *uaddr, int fshared, struct futex_q *q,
-                       int locked)
+static int fixup_owner(u32 __user *uaddr, struct futex_q *q, int locked)
 {
         struct task_struct *owner;
         int ret = 0;
@@ -1622,7 +1660,7 @@ static int fixup_owner(u32 __user *uaddr, int fshared, struct futex_q *q,
                  * did a lock-steal - fix up the PI-state in that case:
                  */
                 if (q->pi_state->owner != current)
-                        ret = fixup_pi_state_owner(uaddr, q, current, fshared);
+                        ret = fixup_pi_state_owner(uaddr, q, current);
                 goto out;
         }
 
@@ -1644,18 +1682,20 @@ static int fixup_owner(u32 __user *uaddr, int fshared, struct futex_q *q,
                 /*
                  * pi_state is incorrect, some other task did a lock steal and
                  * we returned due to timeout or signal without taking the
-                 * rt_mutex. Too late. We can access the rt_mutex_owner without
-                 * locking, as the other task is now blocked on the hash bucket
-                 * lock. Fix the state up.
+                 * rt_mutex. Too late.
                  */
+                raw_spin_lock(&q->pi_state->pi_mutex.wait_lock);
                 owner = rt_mutex_owner(&q->pi_state->pi_mutex);
-                ret = fixup_pi_state_owner(uaddr, q, owner, fshared);
+                if (!owner)
+                        owner = rt_mutex_next_owner(&q->pi_state->pi_mutex);
+                raw_spin_unlock(&q->pi_state->pi_mutex.wait_lock);
+                ret = fixup_pi_state_owner(uaddr, q, owner);
                 goto out;
         }
 
         /*
          * Paranoia check. If we did not take the lock, then we should not be
-         * the owner, nor the pending owner, of the rt_mutex.
+         * the owner of the rt_mutex.
          */
         if (rt_mutex_owner(&q->pi_state->pi_mutex) == current)
                 printk(KERN_ERR "fixup_owner: ret = %d pi-mutex: %p "
@@ -1712,7 +1752,7 @@ static void futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q *q,
  * futex_wait_setup() - Prepare to wait on a futex
  * @uaddr:      the futex userspace address
  * @val:        the expected value
- * @fshared:    whether the futex is shared (1) or not (0)
+ * @flags:      futex flags (FLAGS_SHARED, etc.)
  * @q:          the associated futex_q
  * @hb:         storage for hash_bucket pointer to be returned to caller
  *
@@ -1725,7 +1765,7 @@ static void futex_wait_queue_me(struct futex_hash_bucket *hb, struct futex_q *q,
  *  0 - uaddr contains val and hb has been locked
  * <1 - -EFAULT or -EWOULDBLOCK (uaddr does not contain val) and hb is unlcoked
  */
-static int futex_wait_setup(u32 __user *uaddr, u32 val, int fshared,
+static int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags,
                            struct futex_q *q, struct futex_hash_bucket **hb)
 {
         u32 uval;
@@ -1740,17 +1780,17 @@ static int futex_wait_setup(u32 __user *uaddr, u32 val, int fshared,
          *
          * The basic logical guarantee of a futex is that it blocks ONLY
          * if cond(var) is known to be true at the time of blocking, for
-         * any cond.  If we queued after testing *uaddr, that would open
-         * a race condition where we could block indefinitely with
+         * any cond.  If we locked the hash-bucket after testing *uaddr, that
+         * would open a race condition where we could block indefinitely with
          * cond(var) false, which would violate the guarantee.
          *
-         * A consequence is that futex_wait() can return zero and absorb
-         * a wakeup when *uaddr != val on entry to the syscall.  This is
-         * rare, but normal.
+         * On the other hand, we insert q and release the hash-bucket only
+         * after testing *uaddr.  This guarantees that futex_wait() will NOT
+         * absorb a wakeup if *uaddr does not match the desired values
+         * while the syscall executes.
          */
 retry:
-        q->key = FUTEX_KEY_INIT;
-        ret = get_futex_key(uaddr, fshared, &q->key);
+        ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q->key);
         if (unlikely(ret != 0))
                 return ret;
 
@@ -1766,10 +1806,10 @@ retry_private:
                 if (ret)
                         goto out;
 
-                if (!fshared)
+                if (!(flags & FLAGS_SHARED))
                         goto retry_private;
 
-                put_futex_key(fshared, &q->key);
+                put_futex_key(&q->key);
                 goto retry;
         }
 
@@ -1780,40 +1820,40 @@ retry_private:
 
 out:
         if (ret)
-                put_futex_key(fshared, &q->key);
+                put_futex_key(&q->key);
         return ret;
 }
 
-static int futex_wait(u32 __user *uaddr, int fshared,
-                      u32 val, ktime_t *abs_time, u32 bitset, int clockrt)
+static int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val,
+                      ktime_t *abs_time, u32 bitset)
 {
         struct hrtimer_sleeper timeout, *to = NULL;
         struct restart_block *restart;
         struct futex_hash_bucket *hb;
-        struct futex_q q;
+        struct futex_q q = futex_q_init;
         int ret;
 
         if (!bitset)
                 return -EINVAL;
-
-        q.pi_state = NULL;
         q.bitset = bitset;
-        q.rt_waiter = NULL;
-        q.requeue_pi_key = NULL;
 
         if (abs_time) {
                 to = &timeout;
 
-                hrtimer_init_on_stack(&to->timer, clockrt ? CLOCK_REALTIME :
-                                      CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+                hrtimer_init_on_stack(&to->timer, (flags & FLAGS_CLOCKRT) ?
+                                      CLOCK_REALTIME : CLOCK_MONOTONIC,
+                                      HRTIMER_MODE_ABS);
                 hrtimer_init_sleeper(to, current);
                 hrtimer_set_expires_range_ns(&to->timer, *abs_time,
                                              current->timer_slack_ns);
         }
 
 retry:
-        /* Prepare to wait on uaddr. */
-        ret = futex_wait_setup(uaddr, val, fshared, &q, &hb);
+        /*
+         * Prepare to wait on uaddr. On success, holds hb lock and increments
+         * q.key refs.
+         */
+        ret = futex_wait_setup(uaddr, val, flags, &q, &hb);
         if (ret)
                 goto out;
 
@@ -1822,42 +1862,34 @@ retry:
 
         /* If we were woken (and unqueued), we succeeded, whatever. */
         ret = 0;
+        /* unqueue_me() drops q.key ref */
         if (!unqueue_me(&q))
-                goto out_put_key;
+                goto out;
         ret = -ETIMEDOUT;
         if (to && !to->task)
-                goto out_put_key;
+                goto out;
 
         /*
          * 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);
+        if (!signal_pending(current))
                 goto retry;
-        }
 
         ret = -ERESTARTSYS;
         if (!abs_time)
-                goto out_put_key;
+                goto out;
 
         restart = &current_thread_info()->restart_block;
         restart->fn = futex_wait_restart;
-        restart->futex.uaddr = (u32 *)uaddr;
+        restart->futex.uaddr = uaddr;
         restart->futex.val = val;
         restart->futex.time = abs_time->tv64;
         restart->futex.bitset = bitset;
-        restart->futex.flags = FLAGS_HAS_TIMEOUT;
-
-        if (fshared)
-                restart->futex.flags |= FLAGS_SHARED;
-        if (clockrt)
-                restart->futex.flags |= FLAGS_CLOCKRT;
+        restart->futex.flags = flags | FLAGS_HAS_TIMEOUT;
 
         ret = -ERESTART_RESTARTBLOCK;
 
-out_put_key:
-        put_futex_key(fshared, &q.key);
 out:
         if (to) {
                 hrtimer_cancel(&to->timer);
@@ -1869,8 +1901,7 @@ out:
 
 static long futex_wait_restart(struct restart_block *restart)
 {
-        u32 __user *uaddr = (u32 __user *)restart->futex.uaddr;
-        int fshared = 0;
+        u32 __user *uaddr = restart->futex.uaddr;
         ktime_t t, *tp = NULL;
 
         if (restart->futex.flags & FLAGS_HAS_TIMEOUT) {
@@ -1878,11 +1909,9 @@ static long futex_wait_restart(struct restart_block *restart)
                 tp = &t;
         }
         restart->fn = do_no_restart_syscall;
-        if (restart->futex.flags & FLAGS_SHARED)
-                fshared = 1;
-        return (long)futex_wait(uaddr, fshared, restart->futex.val, tp,
-                                restart->futex.bitset,
-                                restart->futex.flags & FLAGS_CLOCKRT);
+
+        return (long)futex_wait(uaddr, restart->futex.flags,
+                                restart->futex.val, tp, restart->futex.bitset);
 }
 
 
@@ -1892,12 +1921,12 @@ static long futex_wait_restart(struct restart_block *restart)
  * if there are waiters then it will block, it does PI, etc. (Due to
  * races the kernel might see a 0 value of the futex too.)
  */
-static int futex_lock_pi(u32 __user *uaddr, int fshared,
-                         int detect, ktime_t *time, int trylock)
+static int futex_lock_pi(u32 __user *uaddr, unsigned int flags, int detect,
+                         ktime_t *time, int trylock)
 {
         struct hrtimer_sleeper timeout, *to = NULL;
         struct futex_hash_bucket *hb;
-        struct futex_q q;
+        struct futex_q q = futex_q_init;
         int res, ret;
 
         if (refill_pi_state_cache())
@@ -1911,12 +1940,8 @@ static int futex_lock_pi(u32 __user *uaddr, int fshared,
                 hrtimer_set_expires(&to->timer, *time);
         }
 
-        q.pi_state = NULL;
-        q.rt_waiter = NULL;
-        q.requeue_pi_key = NULL;
 retry:
-        q.key = FUTEX_KEY_INIT;
-        ret = get_futex_key(uaddr, fshared, &q.key);
+        ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &q.key);
         if (unlikely(ret != 0))
                 goto out;
 
@@ -1938,7 +1963,7 @@ retry_private:
                          * exit to complete.
                          */
                         queue_unlock(&q, hb);
-                        put_futex_key(fshared, &q.key);
+                        put_futex_key(&q.key);
                         cond_resched();
                         goto retry;
                 default:
@@ -1968,7 +1993,7 @@ retry_private:
          * Fixup the pi_state owner and possibly acquire the lock if we
          * haven't already.
          */
-        res = fixup_owner(uaddr, fshared, &q, !ret);
+        res = fixup_owner(uaddr, &q, !ret);
         /*
          * If fixup_owner() returned an error, proprogate that.  If it acquired
          * the lock, clear our -ETIMEDOUT or -EINTR.
@@ -1992,7 +2017,7 @@ out_unlock_put_key:
         queue_unlock(&q, hb);
 
 out_put_key:
-        put_futex_key(fshared, &q.key);
+        put_futex_key(&q.key);
 out:
         if (to)
                 destroy_hrtimer_on_stack(&to->timer);
@@ -2005,10 +2030,10 @@ uaddr_faulted:
         if (ret)
                 goto out_put_key;
 
-        if (!fshared)
+        if (!(flags & FLAGS_SHARED))
                 goto retry_private;
 
-        put_futex_key(fshared, &q.key);
+        put_futex_key(&q.key);
         goto retry;
 }
 
@@ -2017,13 +2042,13 @@ uaddr_faulted:
  * This is the in-kernel slowpath: we look up the PI state (if any),
  * and do the rt-mutex unlock.
  */
-static int futex_unlock_pi(u32 __user *uaddr, int fshared)
+static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags)
 {
         struct futex_hash_bucket *hb;
         struct futex_q *this, *next;
-        u32 uval;
         struct plist_head *head;
         union futex_key key = FUTEX_KEY_INIT;
+        u32 uval, vpid = task_pid_vnr(current);
         int ret;
 
 retry:
@@ -2032,10 +2057,10 @@ retry:
         /*
          * We release only a lock we actually own:
          */
-        if ((uval & FUTEX_TID_MASK) != task_pid_vnr(current))
+        if ((uval & FUTEX_TID_MASK) != vpid)
                 return -EPERM;
 
-        ret = get_futex_key(uaddr, fshared, &key);
+        ret = get_futex_key(uaddr, flags & FLAGS_SHARED, &key);
         if (unlikely(ret != 0))
                 goto out;
 
@@ -2047,17 +2072,14 @@ retry:
          * again. If it succeeds then we can return without waking
          * anyone else up:
          */
-        if (!(uval & FUTEX_OWNER_DIED))
-                uval = cmpxchg_futex_value_locked(uaddr, task_pid_vnr(current), 0);
-
-
-        if (unlikely(uval == -EFAULT))
+        if (!(uval & FUTEX_OWNER_DIED) &&
+            cmpxchg_futex_value_locked(&uval, uaddr, vpid, 0))
                 goto pi_faulted;
         /*
          * Rare case: we managed to release the lock atomically,
          * no need to wake anyone else up:
          */
-        if (unlikely(uval == task_pid_vnr(current)))
+        if (unlikely(uval == vpid))
                 goto out_unlock;
 
         /*
@@ -2090,14 +2112,14 @@ retry:
 
 out_unlock:
         spin_unlock(&hb->lock);
-        put_futex_key(fshared, &key);
+        put_futex_key(&key);
 
 out:
         return ret;
 
 pi_faulted:
         spin_unlock(&hb->lock);
-        put_futex_key(fshared, &key);
+        put_futex_key(&key);
 
         ret = fault_in_user_writeable(uaddr);
         if (!ret)
@@ -2142,7 +2164,7 @@ int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb,
                  * We were woken prior to requeue by a timeout or a signal.
                  * Unqueue the futex_q and determine which it was.
                  */
-                plist_del(&q->list, &q->list.plist);
+                plist_del(&q->list, &hb->chain);
 
                 /* Handle spurious wakeups gracefully */
                 ret = -EWOULDBLOCK;
@@ -2157,7 +2179,7 @@ int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb,
 /**
  * futex_wait_requeue_pi() - Wait on uaddr and take uaddr2
  * @uaddr:      the futex we initially wait on (non-pi)
- * @fshared:    whether the futexes are shared (1) or not (0).  They must be
+ * @flags:      futex flags (FLAGS_SHARED, FLAGS_CLOCKRT, etc.), they must be
  *              the same type, no requeueing from private to shared, etc.
  * @val:        the expected value of uaddr
  * @abs_time:   absolute timeout
@@ -2195,16 +2217,16 @@ int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb,
  *  0 - On success
  * <0 - On error
  */
-static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared,
+static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
                                  u32 val, ktime_t *abs_time, u32 bitset,
-                                 int clockrt, u32 __user *uaddr2)
+                                 u32 __user *uaddr2)
 {
         struct hrtimer_sleeper timeout, *to = NULL;
         struct rt_mutex_waiter rt_waiter;
         struct rt_mutex *pi_mutex = NULL;
         struct futex_hash_bucket *hb;
-        union futex_key key2;
-        struct futex_q q;
+        union futex_key key2 = FUTEX_KEY_INIT;
+        struct futex_q q = futex_q_init;
         int res, ret;
 
         if (!bitset)
@@ -2212,8 +2234,9 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared,
 
         if (abs_time) {
                 to = &timeout;
-                hrtimer_init_on_stack(&to->timer, clockrt ? CLOCK_REALTIME :
-                                      CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+                hrtimer_init_on_stack(&to->timer, (flags & FLAGS_CLOCKRT) ?
+                                      CLOCK_REALTIME : CLOCK_MONOTONIC,
+                                      HRTIMER_MODE_ABS);
                 hrtimer_init_sleeper(to, current);
                 hrtimer_set_expires_range_ns(&to->timer, *abs_time,
                                              current->timer_slack_ns);
@@ -2226,18 +2249,19 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared,
         debug_rt_mutex_init_waiter(&rt_waiter);
         rt_waiter.task = NULL;
 
-        key2 = FUTEX_KEY_INIT;
-        ret = get_futex_key(uaddr2, fshared, &key2);
+        ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2);
         if (unlikely(ret != 0))
                 goto out;
 
-        q.pi_state = NULL;
         q.bitset = bitset;
         q.rt_waiter = &rt_waiter;
         q.requeue_pi_key = &key2;
 
-        /* Prepare to wait on uaddr. */
-        ret = futex_wait_setup(uaddr, val, fshared, &q, &hb);
+        /*
+         * Prepare to wait on uaddr. On success, increments q.key (key1) ref
+         * count.
+         */
+        ret = futex_wait_setup(uaddr, val, flags, &q, &hb);
         if (ret)
                 goto out_key2;
 
@@ -2254,7 +2278,9 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared,
          * In order for us to be here, we know our q.key == key2, and since
          * we took the hb->lock above, we also know that futex_requeue() has
          * completed and we no longer have to concern ourselves with a wakeup
-         * race with the atomic proxy lock acquition by the requeue code.
+         * race with the atomic proxy lock acquisition by the requeue code. The
+         * futex_requeue dropped our key1 reference and incremented our key2
+         * reference count.
          */
 
         /* Check if the requeue code acquired the second futex for us. */
@@ -2265,8 +2291,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared,
                  */
                 if (q.pi_state && (q.pi_state->owner != current)) {
                         spin_lock(q.lock_ptr);
-                        ret = fixup_pi_state_owner(uaddr2, &q, current,
-                                                   fshared);
+                        ret = fixup_pi_state_owner(uaddr2, &q, current);
                         spin_unlock(q.lock_ptr);
                 }
         } else {
@@ -2285,7 +2310,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared,
                  * Fixup the pi_state owner and possibly acquire the lock if we
                  * haven't already.
                  */
-                res = fixup_owner(uaddr2, fshared, &q, !ret);
+                res = fixup_owner(uaddr2, &q, !ret);
                 /*
                  * If fixup_owner() returned an error, proprogate that.  If it
                  * acquired the lock, clear -ETIMEDOUT or -EINTR.
@@ -2316,9 +2341,9 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared,
         }
 
 out_put_keys:
-        put_futex_key(fshared, &q.key);
+        put_futex_key(&q.key);
 out_key2:
-        put_futex_key(fshared, &key2);
+        put_futex_key(&key2);
 
 out:
         if (to) {
@@ -2393,10 +2418,19 @@ SYSCALL_DEFINE3(get_robust_list, int, pid,
                         goto err_unlock;
                 ret = -EPERM;
                 pcred = __task_cred(p);
+                /* If victim is in different user_ns, then uids are not
+                   comparable, so we must have CAP_SYS_PTRACE */
+                if (cred->user->user_ns != pcred->user->user_ns) {
+                        if (!ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE))
+                                goto err_unlock;
+                        goto ok;
+                }
+                /* If victim is in same user_ns, then uids are comparable */
                 if (cred->euid != pcred->euid &&
                     cred->euid != pcred->uid &&
-                    !capable(CAP_SYS_PTRACE))
+                    !ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE))
                         goto err_unlock;
+ok:
                 head = p->robust_list;
                 rcu_read_unlock();
         }
@@ -2435,11 +2469,20 @@ retry:
                  * userspace.
                  */
                 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
-                nval = futex_atomic_cmpxchg_inatomic(uaddr, uval, mval);
-
-                if (nval == -EFAULT)
-                        return -1;
-
+                /*
+                 * We are not holding a lock here, but we want to have
+                 * the pagefault_disable/enable() protection because
+                 * we want to handle the fault gracefully. If the
+                 * access fails we try to fault in the futex with R/W
+                 * verification via get_user_pages. get_user() above
+                 * does not guarantee R/W access. If that fails we
+                 * give up and leave the futex locked.
+                 */
+                if (cmpxchg_futex_value_locked(&nval, uaddr, uval, mval)) {
+                        if (fault_in_user_writeable(uaddr))
+                                return -1;
+                        goto retry;
+                }
                 if (nval != uval)
                         goto retry;
 
@@ -2458,7 +2501,7 @@ retry:
  */
 static inline int fetch_robust_entry(struct robust_list __user **entry,
                                      struct robust_list __user * __user *head,
-                                     int *pi)
+                                     unsigned int *pi)
 {
         unsigned long uentry;
 
@@ -2481,7 +2524,8 @@ void exit_robust_list(struct task_struct *curr)
 {
         struct robust_list_head __user *head = curr->robust_list;
         struct robust_list __user *entry, *next_entry, *pending;
-        unsigned int limit = ROBUST_LIST_LIMIT, pi, next_pi, pip;
+        unsigned int limit = ROBUST_LIST_LIMIT, pi, pip;
+        unsigned int uninitialized_var(next_pi);
         unsigned long futex_offset;
         int rc;
 
@@ -2542,58 +2586,57 @@ void exit_robust_list(struct task_struct *curr)
 long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
                 u32 __user *uaddr2, u32 val2, u32 val3)
 {
-        int clockrt, ret = -ENOSYS;
-        int cmd = op & FUTEX_CMD_MASK;
-        int fshared = 0;
+        int ret = -ENOSYS, cmd = op & FUTEX_CMD_MASK;
+        unsigned int flags = 0;
 
         if (!(op & FUTEX_PRIVATE_FLAG))
-                fshared = 1;
+                flags |= FLAGS_SHARED;
 
-        clockrt = op & FUTEX_CLOCK_REALTIME;
-        if (clockrt && cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI)
-                return -ENOSYS;
+        if (op & FUTEX_CLOCK_REALTIME) {
+                flags |= FLAGS_CLOCKRT;
+                if (cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI)
+                        return -ENOSYS;
+        }
 
         switch (cmd) {
         case FUTEX_WAIT:
                 val3 = FUTEX_BITSET_MATCH_ANY;
         case FUTEX_WAIT_BITSET:
-                ret = futex_wait(uaddr, fshared, val, timeout, val3, clockrt);
+                ret = futex_wait(uaddr, flags, val, timeout, val3);
                 break;
         case FUTEX_WAKE:
                 val3 = FUTEX_BITSET_MATCH_ANY;
         case FUTEX_WAKE_BITSET:
-                ret = futex_wake(uaddr, fshared, val, val3);
+                ret = futex_wake(uaddr, flags, val, val3);
                 break;
         case FUTEX_REQUEUE:
-                ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, NULL, 0);
+                ret = futex_requeue(uaddr, flags, uaddr2, val, val2, NULL, 0);
                 break;
         case FUTEX_CMP_REQUEUE:
-                ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, &val3,
-                                    0);
+                ret = futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 0);
                 break;
         case FUTEX_WAKE_OP:
-                ret = futex_wake_op(uaddr, fshared, uaddr2, val, val2, val3);
+                ret = futex_wake_op(uaddr, flags, uaddr2, val, val2, val3);
                 break;
         case FUTEX_LOCK_PI:
                 if (futex_cmpxchg_enabled)
-                        ret = futex_lock_pi(uaddr, fshared, val, timeout, 0);
+                        ret = futex_lock_pi(uaddr, flags, val, timeout, 0);
                 break;
         case FUTEX_UNLOCK_PI:
                 if (futex_cmpxchg_enabled)
-                        ret = futex_unlock_pi(uaddr, fshared);
+                        ret = futex_unlock_pi(uaddr, flags);
                 break;
         case FUTEX_TRYLOCK_PI:
                 if (futex_cmpxchg_enabled)
-                        ret = futex_lock_pi(uaddr, fshared, 0, timeout, 1);
+                        ret = futex_lock_pi(uaddr, flags, 0, timeout, 1);
                 break;
         case FUTEX_WAIT_REQUEUE_PI:
                 val3 = FUTEX_BITSET_MATCH_ANY;
-                ret = futex_wait_requeue_pi(uaddr, fshared, val, timeout, val3,
-                                            clockrt, uaddr2);
+                ret = futex_wait_requeue_pi(uaddr, flags, val, timeout, val3,
+                                            uaddr2);
                 break;
         case FUTEX_CMP_REQUEUE_PI:
-                ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, &val3,
-                                    1);
+                ret = futex_requeue(uaddr, flags, uaddr2, val, val2, &val3, 1);
                 break;
         default:
                 ret = -ENOSYS;
@@ -2647,11 +2690,10 @@ static int __init futex_init(void)
          * 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
+         * implementation, the non-functional ones will return
          * -ENOSYS.
          */
-        curval = cmpxchg_futex_value_locked(NULL, 0, 0);
-        if (curval == -EFAULT)
+        if (cmpxchg_futex_value_locked(&curval, NULL, 0, 0) == -EFAULT)
                 futex_cmpxchg_enabled = 1;
 
         for (i = 0; i < ARRAY_SIZE(futex_queues); i++) {