1 files changed, 113 insertions, 94 deletions

diff --git a/kernel/futex/waitwake.c b/kernel/futex/waitwake.c
index 25877d4f2f8f..e2bbe5509ec2 100644
--- a/kernel/futex/waitwake.c
+++ b/kernel/futex/waitwake.c
@@ -154,7 +154,6 @@ void futex_wake_mark(struct wake_q_head *wake_q, struct futex_q *q)
  */
 int futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset)
 {
-	struct futex_hash_bucket *hb;
 	struct futex_q *this, *next;
 	union futex_key key = FUTEX_KEY_INIT;
 	DEFINE_WAKE_Q(wake_q);
@@ -170,7 +169,7 @@ int futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset)
 	if ((flags & FLAGS_STRICT) && !nr_wake)
 		return 0;
 
-	hb = futex_hash(&key);
+	CLASS(hb, hb)(&key);
 
 	/* Make sure we really have tasks to wakeup */
 	if (!futex_hb_waiters_pending(hb))
@@ -253,7 +252,6 @@ int 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;
-	struct futex_hash_bucket *hb1, *hb2;
 	struct futex_q *this, *next;
 	int ret, op_ret;
 	DEFINE_WAKE_Q(wake_q);
@@ -266,67 +264,69 @@ retry:
 	if (unlikely(ret != 0))
 		return ret;
 
-	hb1 = futex_hash(&key1);
-	hb2 = futex_hash(&key2);
-
 retry_private:
-	double_lock_hb(hb1, hb2);
-	op_ret = futex_atomic_op_inuser(op, uaddr2);
-	if (unlikely(op_ret < 0)) {
-		double_unlock_hb(hb1, hb2);
-
-		if (!IS_ENABLED(CONFIG_MMU) ||
-		    unlikely(op_ret != -EFAULT && op_ret != -EAGAIN)) {
-			/*
-			 * we don't get EFAULT from MMU faults if we don't have
-			 * an MMU, but we might get them from range checking
-			 */
-			ret = op_ret;
-			return ret;
-		}
-
-		if (op_ret == -EFAULT) {
-			ret = fault_in_user_writeable(uaddr2);
-			if (ret)
+	if (1) {
+		CLASS(hb, hb1)(&key1);
+		CLASS(hb, hb2)(&key2);
+
+		double_lock_hb(hb1, hb2);
+		op_ret = futex_atomic_op_inuser(op, uaddr2);
+		if (unlikely(op_ret < 0)) {
+			double_unlock_hb(hb1, hb2);
+
+			if (!IS_ENABLED(CONFIG_MMU) ||
+			    unlikely(op_ret != -EFAULT && op_ret != -EAGAIN)) {
+				/*
+				 * we don't get EFAULT from MMU faults if we don't have
+				 * an MMU, but we might get them from range checking
+				 */
+				ret = op_ret;
 				return ret;
-		}
-
-		cond_resched();
-		if (!(flags & FLAGS_SHARED))
-			goto retry_private;
-		goto retry;
-	}
+			}
 
-	plist_for_each_entry_safe(this, next, &hb1->chain, list) {
-		if (futex_match (&this->key, &key1)) {
-			if (this->pi_state || this->rt_waiter) {
-				ret = -EINVAL;
-				goto out_unlock;
+			if (op_ret == -EFAULT) {
+				ret = fault_in_user_writeable(uaddr2);
+				if (ret)
+					return ret;
 			}
-			this->wake(&wake_q, this);
-			if (++ret >= nr_wake)
-				break;
+
+			cond_resched();
+			if (!(flags & FLAGS_SHARED))
+				goto retry_private;
+			goto retry;
 		}
-	}
 
-	if (op_ret > 0) {
-		op_ret = 0;
-		plist_for_each_entry_safe(this, next, &hb2->chain, list) {
-			if (futex_match (&this->key, &key2)) {
+		plist_for_each_entry_safe(this, next, &hb1->chain, list) {
+			if (futex_match(&this->key, &key1)) {
 				if (this->pi_state || this->rt_waiter) {
 					ret = -EINVAL;
 					goto out_unlock;
 				}
 				this->wake(&wake_q, this);
-				if (++op_ret >= nr_wake2)
+				if (++ret >= nr_wake)
 					break;
 			}
 		}
-		ret += op_ret;
-	}
+
+		if (op_ret > 0) {
+			op_ret = 0;
+			plist_for_each_entry_safe(this, next, &hb2->chain, list) {
+				if (futex_match(&this->key, &key2)) {
+					if (this->pi_state || this->rt_waiter) {
+						ret = -EINVAL;
+						goto out_unlock;
+					}
+					this->wake(&wake_q, this);
+					if (++op_ret >= nr_wake2)
+						break;
+				}
+			}
+			ret += op_ret;
+		}
 
 out_unlock:
-	double_unlock_hb(hb1, hb2);
+		double_unlock_hb(hb1, hb2);
+	}
 	wake_up_q(&wake_q);
 	return ret;
 }
@@ -334,23 +334,12 @@ out_unlock:
 static long futex_wait_restart(struct restart_block *restart);
 
 /**
- * futex_wait_queue() - futex_queue() and wait for wakeup, timeout, or signal
- * @hb:		the futex hash bucket, must be locked by the caller
+ * futex_do_wait() - wait for wakeup, timeout, or signal
  * @q:		the futex_q to queue up on
  * @timeout:	the prepared hrtimer_sleeper, or null for no timeout
  */
-void futex_wait_queue(struct futex_hash_bucket *hb, struct futex_q *q,
-			    struct hrtimer_sleeper *timeout)
+void futex_do_wait(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 smp_store_mb() and
-	 * futex_queue() calls spin_unlock() upon completion, both serializing
-	 * access to the hash list and forcing another memory barrier.
-	 */
-	set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
-	futex_queue(q, hb, current);
-
 	/* Arm the timer */
 	if (timeout)
 		hrtimer_sleeper_start_expires(timeout, HRTIMER_MODE_ABS);
@@ -412,12 +401,17 @@ int futex_unqueue_multiple(struct futex_vector *v, int count)
  */
 int futex_wait_multiple_setup(struct futex_vector *vs, int count, int *woken)
 {
-	struct futex_hash_bucket *hb;
 	bool retry = false;
 	int ret, i;
 	u32 uval;
 
 	/*
+	 * Make sure to have a reference on the private_hash such that we
+	 * don't block on rehash after changing the task state below.
+	 */
+	guard(private_hash)();
+
+	/*
 	 * Enqueuing multiple futexes is tricky, because we need to enqueue
 	 * each futex on the list before dealing with the next one to avoid
 	 * deadlocking on the hash bucket. But, before enqueuing, we need to
@@ -451,20 +445,24 @@ retry:
 		struct futex_q *q = &vs[i].q;
 		u32 val = vs[i].w.val;
 
-		hb = futex_q_lock(q);
-		ret = futex_get_value_locked(&uval, uaddr);
+		if (1) {
+			CLASS(hb, hb)(&q->key);
 
-		if (!ret && uval == val) {
-			/*
-			 * The bucket lock can't be held while dealing with the
-			 * next futex. Queue each futex at this moment so hb can
-			 * be unlocked.
-			 */
-			futex_queue(q, hb, current);
-			continue;
-		}
+			futex_q_lock(q, hb);
+			ret = futex_get_value_locked(&uval, uaddr);
+
+			if (!ret && uval == val) {
+				/*
+				 * The bucket lock can't be held while dealing with the
+				 * next futex. Queue each futex at this moment so hb can
+				 * be unlocked.
+				 */
+				futex_queue(q, hb, current);
+				continue;
+			}
 
-		futex_q_unlock(hb);
+			futex_q_unlock(hb);
+		}
 		__set_current_state(TASK_RUNNING);
 
 		/*
@@ -578,7 +576,8 @@ int futex_wait_multiple(struct futex_vector *vs, unsigned int count,
  * @val:	the expected value
  * @flags:	futex flags (FLAGS_SHARED, etc.)
  * @q:		the associated futex_q
- * @hb:		storage for hash_bucket pointer to be returned to caller
+ * @key2:	the second futex_key if used for requeue PI
+ * @task:	Task queueing this futex
  *
  * Setup the futex_q and locate the hash_bucket.  Get the futex value and
  * compare it with the expected value.  Handle atomic faults internally.
@@ -586,10 +585,12 @@ int futex_wait_multiple(struct futex_vector *vs, unsigned int count,
  *
  * Return:
  *  -  0 - uaddr contains val and hb has been locked;
- *  - <1 - -EFAULT or -EWOULDBLOCK (uaddr does not contain val) and hb is unlocked
+ *  - <0 - On error and the hb is unlocked. A possible reason: the uaddr can not
+ *	   be read, does not contain the expected value or is not properly aligned.
  */
 int futex_wait_setup(u32 __user *uaddr, u32 val, unsigned int flags,
-		     struct futex_q *q, struct futex_hash_bucket **hb)
+		     struct futex_q *q, union futex_key *key2,
+		     struct task_struct *task)
 {
 	u32 uval;
 	int ret;
@@ -618,26 +619,45 @@ retry:
 		return ret;
 
 retry_private:
-	*hb = futex_q_lock(q);
+	if (1) {
+		CLASS(hb, hb)(&q->key);
 
-	ret = futex_get_value_locked(&uval, uaddr);
+		futex_q_lock(q, hb);
 
-	if (ret) {
-		futex_q_unlock(*hb);
+		ret = futex_get_value_locked(&uval, uaddr);
 
-		ret = get_user(uval, uaddr);
-		if (ret)
-			return ret;
+		if (ret) {
+			futex_q_unlock(hb);
 
-		if (!(flags & FLAGS_SHARED))
-			goto retry_private;
+			ret = get_user(uval, uaddr);
+			if (ret)
+				return ret;
 
-		goto retry;
-	}
+			if (!(flags & FLAGS_SHARED))
+				goto retry_private;
+
+			goto retry;
+		}
 
-	if (uval != val) {
-		futex_q_unlock(*hb);
-		ret = -EWOULDBLOCK;
+		if (uval != val) {
+			futex_q_unlock(hb);
+			return -EWOULDBLOCK;
+		}
+
+		if (key2 && futex_match(&q->key, key2)) {
+			futex_q_unlock(hb);
+			return -EINVAL;
+		}
+
+		/*
+		 * The task state is guaranteed to be set before another task can
+		 * wake it. set_current_state() is implemented using smp_store_mb() and
+		 * futex_queue() calls spin_unlock() upon completion, both serializing
+		 * access to the hash list and forcing another memory barrier.
+		 */
+		if (task == current)
+			set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
+		futex_queue(q, hb, task);
 	}
 
 	return ret;
@@ -647,7 +667,6 @@ int __futex_wait(u32 __user *uaddr, unsigned int flags, u32 val,
 		 struct hrtimer_sleeper *to, u32 bitset)
 {
 	struct futex_q q = futex_q_init;
-	struct futex_hash_bucket *hb;
 	int ret;
 
 	if (!bitset)
@@ -660,12 +679,12 @@ retry:
 	 * Prepare to wait on uaddr. On success, it holds hb->lock and q
 	 * is initialized.
 	 */
-	ret = futex_wait_setup(uaddr, val, flags, &q, &hb);
+	ret = futex_wait_setup(uaddr, val, flags, &q, NULL, current);
 	if (ret)
 		return ret;
 
 	/* futex_queue and wait for wakeup, timeout, or a signal. */
-	futex_wait_queue(hb, &q, to);
+	futex_do_wait(&q, to);
 
 	/* If we were woken (and unqueued), we succeeded, whatever. */
 	if (!futex_unqueue(&q))