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-rw-r--r--kernel/futex.c519
1 files changed, 500 insertions, 19 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index dbe857aa438..185c981d89e 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -19,6 +19,10 @@
* PRIVATE futexes by Eric Dumazet
* Copyright (C) 2007 Eric Dumazet <dada1@cosmosbay.com>
*
+ * Requeue-PI support by Darren Hart <dvhltc@us.ibm.com>
+ * Copyright (C) IBM Corporation, 2009
+ * Thanks to Thomas Gleixner for conceptual design and careful reviews.
+ *
* Thanks to Ben LaHaise for yelling "hashed waitqueues" loudly
* enough at me, Linus for the original (flawed) idea, Matthew
* Kirkwood for proof-of-concept implementation.
@@ -109,6 +113,9 @@ struct futex_q {
struct futex_pi_state *pi_state;
struct task_struct *task;
+ /* rt_waiter storage for requeue_pi: */
+ struct rt_mutex_waiter *rt_waiter;
+
/* Bitset for the optional bitmasked wakeup */
u32 bitset;
};
@@ -827,7 +834,7 @@ static int futex_wake(u32 __user *uaddr, int fshared, int nr_wake, u32 bitset)
plist_for_each_entry_safe(this, next, head, list) {
if (match_futex (&this->key, &key)) {
- if (this->pi_state) {
+ if (this->pi_state || this->rt_waiter) {
ret = -EINVAL;
break;
}
@@ -968,20 +975,138 @@ void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1,
q->key = *key2;
}
-/*
- * Requeue all waiters hashed on one physical page to another
- * physical page.
+/**
+ * requeue_pi_wake_futex() - Wake a task that acquired the lock during requeue
+ * q: the futex_q
+ * key: the key of the requeue target futex
+ *
+ * During futex_requeue, with requeue_pi=1, it is possible to acquire the
+ * target futex if it is uncontended or via a lock steal. Set the futex_q key
+ * to the requeue target futex so the waiter can detect the wakeup on the right
+ * futex, but remove it from the hb and NULL the rt_waiter so it can detect
+ * atomic lock acquisition. Must be called with the q->lock_ptr held.
+ */
+static inline
+void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key)
+{
+ drop_futex_key_refs(&q->key);
+ get_futex_key_refs(key);
+ q->key = *key;
+
+ WARN_ON(plist_node_empty(&q->list));
+ plist_del(&q->list, &q->list.plist);
+
+ WARN_ON(!q->rt_waiter);
+ q->rt_waiter = NULL;
+
+ wake_up(&q->waiter);
+}
+
+/**
+ * futex_proxy_trylock_atomic() - Attempt an atomic lock for the top waiter
+ * @pifutex: the user address of the to futex
+ * @hb1: the from futex hash bucket, must be locked by the caller
+ * @hb2: the to futex hash bucket, must be locked by the caller
+ * @key1: the from futex key
+ * @key2: the to futex key
+ *
+ * Try and get the lock on behalf of the top waiter if we can do it atomically.
+ * Wake the top waiter if we succeed. hb1 and hb2 must be held by the caller.
+ *
+ * Returns:
+ * 0 - failed to acquire the lock atomicly
+ * 1 - acquired the lock
+ * <0 - error
+ */
+static int futex_proxy_trylock_atomic(u32 __user *pifutex,
+ struct futex_hash_bucket *hb1,
+ struct futex_hash_bucket *hb2,
+ union futex_key *key1, union futex_key *key2,
+ struct futex_pi_state **ps)
+{
+ struct futex_q *top_waiter;
+ u32 curval;
+ int ret;
+
+ if (get_futex_value_locked(&curval, pifutex))
+ return -EFAULT;
+
+ top_waiter = futex_top_waiter(hb1, key1);
+
+ /* There are no waiters, nothing for us to do. */
+ if (!top_waiter)
+ return 0;
+
+ /*
+ * Either take the lock for top_waiter or set the FUTEX_WAITERS bit.
+ * The pi_state is returned in ps in contended cases.
+ */
+ ret = futex_lock_pi_atomic(pifutex, hb2, key2, ps, top_waiter->task);
+ if (ret == 1)
+ requeue_pi_wake_futex(top_waiter, key2);
+
+ return ret;
+}
+
+/**
+ * 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)
+ *
+ * Requeue waiters on uaddr1 to uaddr2. In the requeue_pi case, try to acquire
+ * uaddr2 atomically on behalf of the top waiter.
+ *
+ * Returns:
+ * >=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 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;
+ struct futex_pi_state *pi_state = NULL;
struct futex_hash_bucket *hb1, *hb2;
struct plist_head *head1;
struct futex_q *this, *next;
- int ret, drop_count = 0;
+ u32 curval2;
+
+ if (requeue_pi) {
+ /*
+ * requeue_pi requires a pi_state, try to allocate it now
+ * without any locks in case it fails.
+ */
+ if (refill_pi_state_cache())
+ return -ENOMEM;
+ /*
+ * requeue_pi must wake as many tasks as it can, up to nr_wake
+ * + nr_requeue, since it acquires the rt_mutex prior to
+ * returning to userspace, so as to not leave the rt_mutex with
+ * waiters and no owner. However, second and third wake-ups
+ * cannot be predicted as they involve race conditions with the
+ * first wake and a fault while looking up the pi_state. Both
+ * pthread_cond_signal() and pthread_cond_broadcast() should
+ * use nr_wake=1.
+ */
+ if (nr_wake != 1)
+ return -EINVAL;
+ }
retry:
+ if (pi_state != NULL) {
+ /*
+ * We will have to lookup the pi_state again, so free this one
+ * to keep the accounting correct.
+ */
+ free_pi_state(pi_state);
+ pi_state = NULL;
+ }
+
ret = get_futex_key(uaddr1, fshared, &key1);
if (unlikely(ret != 0))
goto out;
@@ -1020,19 +1145,94 @@ retry_private:
}
}
+ if (requeue_pi && (task_count - nr_wake < nr_requeue)) {
+ /* Attempt to acquire uaddr2 and wake the top_waiter. */
+ ret = futex_proxy_trylock_atomic(uaddr2, hb1, hb2, &key1,
+ &key2, &pi_state);
+
+ /*
+ * At this point the top_waiter has either taken uaddr2 or is
+ * waiting on it. If the former, then the pi_state will not
+ * exist yet, look it up one more time to ensure we have a
+ * reference to it.
+ */
+ if (ret == 1) {
+ WARN_ON(pi_state);
+ task_count++;
+ ret = get_futex_value_locked(&curval2, uaddr2);
+ if (!ret)
+ ret = lookup_pi_state(curval2, hb2, &key2,
+ &pi_state);
+ }
+
+ switch (ret) {
+ case 0:
+ break;
+ case -EFAULT:
+ double_unlock_hb(hb1, hb2);
+ put_futex_key(fshared, &key2);
+ put_futex_key(fshared, &key1);
+ ret = get_user(curval2, uaddr2);
+ if (!ret)
+ goto retry;
+ goto out;
+ case -EAGAIN:
+ /* The owner was exiting, try again. */
+ double_unlock_hb(hb1, hb2);
+ put_futex_key(fshared, &key2);
+ put_futex_key(fshared, &key1);
+ cond_resched();
+ goto retry;
+ default:
+ goto out_unlock;
+ }
+ }
+
head1 = &hb1->chain;
plist_for_each_entry_safe(this, next, head1, list) {
- if (!match_futex (&this->key, &key1))
+ if (task_count - nr_wake >= nr_requeue)
+ break;
+
+ if (!match_futex(&this->key, &key1))
continue;
- if (++ret <= nr_wake) {
+
+ WARN_ON(!requeue_pi && this->rt_waiter);
+ WARN_ON(requeue_pi && !this->rt_waiter);
+
+ /*
+ * Wake nr_wake waiters. For requeue_pi, if we acquired the
+ * lock, we already woke the top_waiter. If not, it will be
+ * woken by futex_unlock_pi().
+ */
+ if (++task_count <= nr_wake && !requeue_pi) {
wake_futex(this);
- } else {
- requeue_futex(this, hb1, hb2, &key2);
- drop_count++;
+ continue;
+ }
- if (ret - nr_wake >= nr_requeue)
- break;
+ /*
+ * Requeue nr_requeue waiters and possibly one more in the case
+ * of requeue_pi if we couldn't acquire the lock atomically.
+ */
+ if (requeue_pi) {
+ /* Prepare the waiter to take the rt_mutex. */
+ atomic_inc(&pi_state->refcount);
+ this->pi_state = pi_state;
+ ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex,
+ this->rt_waiter,
+ this->task, 1);
+ if (ret == 1) {
+ /* We got the lock. */
+ requeue_pi_wake_futex(this, &key2);
+ continue;
+ } else if (ret) {
+ /* -EDEADLK */
+ this->pi_state = NULL;
+ free_pi_state(pi_state);
+ goto out_unlock;
+ }
}
+ requeue_futex(this, hb1, hb2, &key2);
+ drop_count++;
}
out_unlock:
@@ -1047,7 +1247,9 @@ out_put_keys:
out_put_key1:
put_futex_key(fshared, &key1);
out:
- return ret;
+ if (pi_state != NULL)
+ free_pi_state(pi_state);
+ return ret ? ret : task_count;
}
/* The key must be already stored in q->key. */
@@ -1270,6 +1472,7 @@ handle_fault:
#define FLAGS_HAS_TIMEOUT 0x04
static long futex_wait_restart(struct restart_block *restart);
+static long futex_lock_pi_restart(struct restart_block *restart);
/**
* fixup_owner() - Post lock pi_state and corner case management
@@ -1489,6 +1692,7 @@ static int futex_wait(u32 __user *uaddr, int fshared,
q.pi_state = NULL;
q.bitset = bitset;
+ q.rt_waiter = NULL;
if (abs_time) {
to = &timeout;
@@ -1596,6 +1800,7 @@ static int futex_lock_pi(u32 __user *uaddr, int fshared,
}
q.pi_state = NULL;
+ q.rt_waiter = NULL;
retry:
q.key = FUTEX_KEY_INIT;
ret = get_futex_key(uaddr, fshared, &q.key);
@@ -1701,6 +1906,20 @@ uaddr_faulted:
goto retry;
}
+static long futex_lock_pi_restart(struct restart_block *restart)
+{
+ u32 __user *uaddr = (u32 __user *)restart->futex.uaddr;
+ ktime_t t, *tp = NULL;
+ int fshared = restart->futex.flags & FLAGS_SHARED;
+
+ if (restart->futex.flags & FLAGS_HAS_TIMEOUT) {
+ t.tv64 = restart->futex.time;
+ tp = &t;
+ }
+ restart->fn = do_no_restart_syscall;
+
+ return (long)futex_lock_pi(uaddr, fshared, restart->futex.val, tp, 0);
+}
/*
* Userspace attempted a TID -> 0 atomic transition, and failed.
@@ -1803,6 +2022,253 @@ pi_faulted:
return ret;
}
+/**
+ * handle_early_requeue_pi_wakeup() - Detect early wakeup on the initial futex
+ * @hb: the hash_bucket futex_q was original enqueued on
+ * @q: the futex_q woken while waiting to be requeued
+ * @key2: the futex_key of the requeue target futex
+ * @timeout: the timeout associated with the wait (NULL if none)
+ *
+ * Detect if the task was woken on the initial futex as opposed to the requeue
+ * target futex. If so, determine if it was a timeout or a signal that caused
+ * the wakeup and return the appropriate error code to the caller. Must be
+ * called with the hb lock held.
+ *
+ * Returns
+ * 0 - no early wakeup detected
+ * <0 - -ETIMEDOUT or -ERESTARTSYS (FIXME: or ERESTARTNOINTR?)
+ */
+static inline
+int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb,
+ struct futex_q *q, union futex_key *key2,
+ struct hrtimer_sleeper *timeout)
+{
+ int ret = 0;
+
+ /*
+ * With the hb lock held, we avoid races while we process the wakeup.
+ * We only need to hold hb (and not hb2) to ensure atomicity as the
+ * wakeup code can't change q.key from uaddr to uaddr2 if we hold hb.
+ * It can't be requeued from uaddr2 to something else since we don't
+ * support a PI aware source futex for requeue.
+ */
+ if (!match_futex(&q->key, key2)) {
+ WARN_ON(q->lock_ptr && (&hb->lock != q->lock_ptr));
+ /*
+ * 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);
+ drop_futex_key_refs(&q->key);
+
+ if (timeout && !timeout->task)
+ ret = -ETIMEDOUT;
+ else {
+ /*
+ * We expect signal_pending(current), but another
+ * thread may have handled it for us already.
+ */
+ /* FIXME: ERESTARTSYS or ERESTARTNOINTR? Do we care if
+ * the user specified SA_RESTART or not? */
+ ret = -ERESTARTSYS;
+ }
+ }
+ return ret;
+}
+
+/**
+ * futex_wait_requeue_pi() - Wait on uaddr and take uaddr2
+ * @uaddr: the futex we initialyl wait on (non-pi)
+ * @fshared: whether the futexes are shared (1) or not (0). They must be
+ * the same type, no requeueing from private to shared, etc.
+ * @val: the expected value of uaddr
+ * @abs_time: absolute timeout
+ * @bitset: 32 bit wakeup bitset set by userspace, defaults to all.
+ * @clockrt: whether to use CLOCK_REALTIME (1) or CLOCK_MONOTONIC (0)
+ * @uaddr2: the pi futex we will take prior to returning to user-space
+ *
+ * The caller will wait on uaddr and will be requeued by futex_requeue() to
+ * uaddr2 which must be PI aware. Normal wakeup will wake on uaddr2 and
+ * complete the acquisition of the rt_mutex prior to returning to userspace.
+ * This ensures the rt_mutex maintains an owner when it has waiters; without
+ * one, the pi logic wouldn't know which task to boost/deboost, if there was a
+ * need to.
+ *
+ * We call schedule in futex_wait_queue_me() when we enqueue and return there
+ * via the following:
+ * 1) wakeup on uaddr2 after an atomic lock acquisition by futex_requeue()
+ * 2) wakeup on uaddr2 after a requeue and subsequent unlock
+ * 3) signal (before or after requeue)
+ * 4) timeout (before or after requeue)
+ *
+ * If 3, we setup a restart_block with futex_wait_requeue_pi() as the function.
+ *
+ * If 2, we may then block on trying to take the rt_mutex and return via:
+ * 5) successful lock
+ * 6) signal
+ * 7) timeout
+ * 8) other lock acquisition failure
+ *
+ * If 6, we setup a restart_block with futex_lock_pi() as the function.
+ *
+ * If 4 or 7, we cleanup and return with -ETIMEDOUT.
+ *
+ * Returns:
+ * 0 - On success
+ * <0 - On error
+ */
+static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared,
+ u32 val, ktime_t *abs_time, u32 bitset,
+ int clockrt, u32 __user *uaddr2)
+{
+ struct hrtimer_sleeper timeout, *to = NULL;
+ struct rt_mutex_waiter rt_waiter;
+ struct rt_mutex *pi_mutex = NULL;
+ DECLARE_WAITQUEUE(wait, current);
+ struct restart_block *restart;
+ struct futex_hash_bucket *hb;
+ union futex_key key2;
+ struct futex_q q;
+ int res, ret;
+ u32 uval;
+
+ if (!bitset)
+ return -EINVAL;
+
+ if (abs_time) {
+ to = &timeout;
+ hrtimer_init_on_stack(&to->timer, 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);
+ }
+
+ /*
+ * The waiter is allocated on our stack, manipulated by the requeue
+ * code while we sleep on uaddr.
+ */
+ debug_rt_mutex_init_waiter(&rt_waiter);
+ rt_waiter.task = NULL;
+
+ q.pi_state = NULL;
+ q.bitset = bitset;
+ q.rt_waiter = &rt_waiter;
+
+ key2 = FUTEX_KEY_INIT;
+ ret = get_futex_key(uaddr2, fshared, &key2);
+ if (unlikely(ret != 0))
+ goto out;
+
+ /* Prepare to wait on uaddr. */
+ ret = futex_wait_setup(uaddr, val, fshared, &q, &hb);
+ if (ret) {
+ put_futex_key(fshared, &key2);
+ goto out;
+ }
+
+ /* Queue the futex_q, drop the hb lock, wait for wakeup. */
+ futex_wait_queue_me(hb, &q, to, &wait);
+
+ spin_lock(&hb->lock);
+ ret = handle_early_requeue_pi_wakeup(hb, &q, &key2, to);
+ spin_unlock(&hb->lock);
+ if (ret)
+ goto out_put_keys;
+
+ /*
+ * 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.
+ */
+
+ /* Check if the requeue code acquired the second futex for us. */
+ if (!q.rt_waiter) {
+ /*
+ * Got the lock. We might not be the anticipated owner if we
+ * did a lock-steal - fix up the PI-state in that case.
+ */
+ if (q.pi_state && (q.pi_state->owner != current)) {
+ spin_lock(q.lock_ptr);
+ ret = fixup_pi_state_owner(uaddr2, &q, current,
+ fshared);
+ spin_unlock(q.lock_ptr);
+ }
+ } else {
+ /*
+ * We have been woken up by futex_unlock_pi(), a timeout, or a
+ * signal. futex_unlock_pi() will not destroy the lock_ptr nor
+ * the pi_state.
+ */
+ WARN_ON(!&q.pi_state);
+ pi_mutex = &q.pi_state->pi_mutex;
+ ret = rt_mutex_finish_proxy_lock(pi_mutex, to, &rt_waiter, 1);
+ debug_rt_mutex_free_waiter(&rt_waiter);
+
+ spin_lock(q.lock_ptr);
+ /*
+ * Fixup the pi_state owner and possibly acquire the lock if we
+ * haven't already.
+ */
+ res = fixup_owner(uaddr2, fshared, &q, !ret);
+ /*
+ * If fixup_owner() returned an error, proprogate that. If it
+ * acquired the lock, clear our -ETIMEDOUT or -EINTR.
+ */
+ if (res)
+ ret = (res < 0) ? res : 0;
+
+ /* Unqueue and drop the lock. */
+ unqueue_me_pi(&q);
+ }
+
+ /*
+ * If fixup_pi_state_owner() faulted and was unable to handle the
+ * fault, unlock the rt_mutex and return the fault to userspace.
+ */
+ if (ret == -EFAULT) {
+ if (rt_mutex_owner(pi_mutex) == current)
+ rt_mutex_unlock(pi_mutex);
+ } else if (ret == -EINTR) {
+ ret = -EFAULT;
+ if (get_user(uval, uaddr2))
+ goto out_put_keys;
+
+ /*
+ * We've already been requeued, so restart by calling
+ * futex_lock_pi() directly, rather then returning to this
+ * function.
+ */
+ ret = -ERESTART_RESTARTBLOCK;
+ restart = &current_thread_info()->restart_block;
+ restart->fn = futex_lock_pi_restart;
+ restart->futex.uaddr = (u32 *)uaddr2;
+ restart->futex.val = uval;
+ restart->futex.flags = 0;
+ if (abs_time) {
+ restart->futex.flags |= FLAGS_HAS_TIMEOUT;
+ restart->futex.time = abs_time->tv64;
+ }
+
+ if (fshared)
+ restart->futex.flags |= FLAGS_SHARED;
+ if (clockrt)
+ restart->futex.flags |= FLAGS_CLOCKRT;
+ }
+
+out_put_keys:
+ put_futex_key(fshared, &q.key);
+ put_futex_key(fshared, &key2);
+
+out:
+ if (to) {
+ hrtimer_cancel(&to->timer);
+ destroy_hrtimer_on_stack(&to->timer);
+ }
+ return ret;
+}
+
/*
* Support for robust futexes: the kernel cleans up held futexes at
* thread exit time.
@@ -2025,7 +2491,7 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
fshared = 1;
clockrt = op & FUTEX_CLOCK_REALTIME;
- if (clockrt && cmd != FUTEX_WAIT_BITSET)
+ if (clockrt && cmd != FUTEX_WAIT_BITSET && cmd != FUTEX_WAIT_REQUEUE_PI)
return -ENOSYS;
switch (cmd) {
@@ -2040,10 +2506,11 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
ret = futex_wake(uaddr, fshared, val, val3);
break;
case FUTEX_REQUEUE:
- ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, NULL);
+ ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, NULL, 0);
break;
case FUTEX_CMP_REQUEUE:
- ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, &val3);
+ ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, &val3,
+ 0);
break;
case FUTEX_WAKE_OP:
ret = futex_wake_op(uaddr, fshared, uaddr2, val, val2, val3);
@@ -2060,6 +2527,18 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
if (futex_cmpxchg_enabled)
ret = futex_lock_pi(uaddr, fshared, 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);
+ break;
+ case FUTEX_REQUEUE_PI:
+ ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, NULL, 1);
+ break;
+ case FUTEX_CMP_REQUEUE_PI:
+ ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, &val3,
+ 1);
+ break;
default:
ret = -ENOSYS;
}
@@ -2077,7 +2556,8 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
int cmd = op & FUTEX_CMD_MASK;
if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||
- cmd == FUTEX_WAIT_BITSET)) {
+ cmd == FUTEX_WAIT_BITSET ||
+ cmd == FUTEX_WAIT_REQUEUE_PI)) {
if (copy_from_user(&ts, utime, sizeof(ts)) != 0)
return -EFAULT;
if (!timespec_valid(&ts))
@@ -2089,10 +2569,11 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
tp = &t;
}
/*
- * requeue parameter in 'utime' if cmd == FUTEX_REQUEUE.
+ * requeue parameter in 'utime' if cmd == FUTEX_*_REQUEUE_*.
* number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP.
*/
if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
+ cmd == FUTEX_REQUEUE_PI || cmd == FUTEX_CMP_REQUEUE_PI ||
cmd == FUTEX_WAKE_OP)
val2 = (u32) (unsigned long) utime;