X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Ffutex.c;h=d9b3a2228f9d8c184719ef5052f37e26b2913195;hb=d5aa407f59f5b83d2c50ec88f5bf56d40f1f8978;hp=1e176f3ab26cfc2200ed793a369cbaeb68241d05;hpb=eaaea8036d0261d87d7072c5bc88c7ea730c18ac;p=safe%2Fjmp%2Flinux-2.6

diff --git a/kernel/futex.c b/kernel/futex.c
index 1e176f3..d9b3a22 100644
--- 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);
 }
@@ -202,8 +203,6 @@ static void drop_futex_key_refs(union futex_key *key)
  * @uaddr:	virtual address of the futex
  * @fshared:	0 for a PROCESS_PRIVATE futex, 1 for PROCESS_SHARED
  * @key:	address where result is stored.
- * @rw:		mapping needs to be read/write (values: VERIFY_READ,
- * 		VERIFY_WRITE)
  *
  * Returns a negative error code or 0
  * The key words are stored in *key on success.
@@ -215,7 +214,7 @@ static void drop_futex_key_refs(union futex_key *key)
  * lock_page() might sleep, the caller should not hold a spinlock.
  */
 static int
-get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw)
+get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key)
 {
 	unsigned long address = (unsigned long)uaddr;
 	struct mm_struct *mm = current->mm;
@@ -238,7 +237,7 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw)
 	 *        but access_ok() should be faster than find_vma()
 	 */
 	if (!fshared) {
-		if (unlikely(!access_ok(rw, uaddr, sizeof(u32))))
+		if (unlikely(!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))))
 			return -EFAULT;
 		key->private.mm = mm;
 		key->private.address = address;
@@ -247,7 +246,7 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw)
 	}
 
 again:
-	err = get_user_pages_fast(address, 1, rw == VERIFY_WRITE, &page);
+	err = get_user_pages_fast(address, 1, 1, &page);
 	if (err < 0)
 		return err;
 
@@ -303,8 +302,14 @@ void put_futex_key(int fshared, union futex_key *key)
  */
 static int fault_in_user_writeable(u32 __user *uaddr)
 {
-	int ret = get_user_pages(current, current->mm, (unsigned long)uaddr,
-				 1, 1, 0, NULL, NULL);
+	struct mm_struct *mm = current->mm;
+	int ret;
+
+	down_read(&mm->mmap_sem);
+	ret = get_user_pages(current, mm, (unsigned long)uaddr,
+			     1, 1, 0, NULL, NULL);
+	up_read(&mm->mmap_sem);
+
 	return ret < 0 ? ret : 0;
 }
 
@@ -396,9 +401,9 @@ static void free_pi_state(struct futex_pi_state *pi_state)
 	 * and has cleaned up the pi_state already
 	 */
 	if (pi_state->owner) {
-		spin_lock_irq(&pi_state->owner->pi_lock);
+		raw_spin_lock_irq(&pi_state->owner->pi_lock);
 		list_del_init(&pi_state->list);
-		spin_unlock_irq(&pi_state->owner->pi_lock);
+		raw_spin_unlock_irq(&pi_state->owner->pi_lock);
 
 		rt_mutex_proxy_unlock(&pi_state->pi_mutex, pi_state->owner);
 	}
@@ -463,18 +468,18 @@ void exit_pi_state_list(struct task_struct *curr)
 	 * pi_state_list anymore, but we have to be careful
 	 * versus waiters unqueueing themselves:
 	 */
-	spin_lock_irq(&curr->pi_lock);
+	raw_spin_lock_irq(&curr->pi_lock);
 	while (!list_empty(head)) {
 
 		next = head->next;
 		pi_state = list_entry(next, struct futex_pi_state, list);
 		key = pi_state->key;
 		hb = hash_futex(&key);
-		spin_unlock_irq(&curr->pi_lock);
+		raw_spin_unlock_irq(&curr->pi_lock);
 
 		spin_lock(&hb->lock);
 
-		spin_lock_irq(&curr->pi_lock);
+		raw_spin_lock_irq(&curr->pi_lock);
 		/*
 		 * We dropped the pi-lock, so re-check whether this
 		 * task still owns the PI-state:
@@ -488,15 +493,15 @@ void exit_pi_state_list(struct task_struct *curr)
 		WARN_ON(list_empty(&pi_state->list));
 		list_del_init(&pi_state->list);
 		pi_state->owner = NULL;
-		spin_unlock_irq(&curr->pi_lock);
+		raw_spin_unlock_irq(&curr->pi_lock);
 
 		rt_mutex_unlock(&pi_state->pi_mutex);
 
 		spin_unlock(&hb->lock);
 
-		spin_lock_irq(&curr->pi_lock);
+		raw_spin_lock_irq(&curr->pi_lock);
 	}
-	spin_unlock_irq(&curr->pi_lock);
+	raw_spin_unlock_irq(&curr->pi_lock);
 }
 
 static int
@@ -551,7 +556,7 @@ lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
 	 * change of the task flags, we do this protected by
 	 * p->pi_lock:
 	 */
-	spin_lock_irq(&p->pi_lock);
+	raw_spin_lock_irq(&p->pi_lock);
 	if (unlikely(p->flags & PF_EXITING)) {
 		/*
 		 * The task is on the way out. When PF_EXITPIDONE is
@@ -560,7 +565,7 @@ lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
 		 */
 		int ret = (p->flags & PF_EXITPIDONE) ? -ESRCH : -EAGAIN;
 
-		spin_unlock_irq(&p->pi_lock);
+		raw_spin_unlock_irq(&p->pi_lock);
 		put_task_struct(p);
 		return ret;
 	}
@@ -579,7 +584,7 @@ lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
 	WARN_ON(!list_empty(&pi_state->list));
 	list_add(&pi_state->list, &p->pi_state_list);
 	pi_state->owner = p;
-	spin_unlock_irq(&p->pi_lock);
+	raw_spin_unlock_irq(&p->pi_lock);
 
 	put_task_struct(p);
 
@@ -753,7 +758,7 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this)
 	if (!pi_state)
 		return -EINVAL;
 
-	spin_lock(&pi_state->pi_mutex.wait_lock);
+	raw_spin_lock(&pi_state->pi_mutex.wait_lock);
 	new_owner = rt_mutex_next_owner(&pi_state->pi_mutex);
 
 	/*
@@ -782,23 +787,23 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this)
 		else if (curval != uval)
 			ret = -EINVAL;
 		if (ret) {
-			spin_unlock(&pi_state->pi_mutex.wait_lock);
+			raw_spin_unlock(&pi_state->pi_mutex.wait_lock);
 			return ret;
 		}
 	}
 
-	spin_lock_irq(&pi_state->owner->pi_lock);
+	raw_spin_lock_irq(&pi_state->owner->pi_lock);
 	WARN_ON(list_empty(&pi_state->list));
 	list_del_init(&pi_state->list);
-	spin_unlock_irq(&pi_state->owner->pi_lock);
+	raw_spin_unlock_irq(&pi_state->owner->pi_lock);
 
-	spin_lock_irq(&new_owner->pi_lock);
+	raw_spin_lock_irq(&new_owner->pi_lock);
 	WARN_ON(!list_empty(&pi_state->list));
 	list_add(&pi_state->list, &new_owner->pi_state_list);
 	pi_state->owner = new_owner;
-	spin_unlock_irq(&new_owner->pi_lock);
+	raw_spin_unlock_irq(&new_owner->pi_lock);
 
-	spin_unlock(&pi_state->pi_mutex.wait_lock);
+	raw_spin_unlock(&pi_state->pi_mutex.wait_lock);
 	rt_mutex_unlock(&pi_state->pi_mutex);
 
 	return 0;
@@ -860,7 +865,7 @@ 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, VERIFY_READ);
+	ret = get_futex_key(uaddr, fshared, &key);
 	if (unlikely(ret != 0))
 		goto out;
 
@@ -906,10 +911,10 @@ futex_wake_op(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
 	int ret, op_ret;
 
 retry:
-	ret = get_futex_key(uaddr1, fshared, &key1, VERIFY_READ);
+	ret = get_futex_key(uaddr1, fshared, &key1);
 	if (unlikely(ret != 0))
 		goto out;
-	ret = get_futex_key(uaddr2, fshared, &key2, VERIFY_WRITE);
+	ret = get_futex_key(uaddr2, fshared, &key2);
 	if (unlikely(ret != 0))
 		goto out_put_key1;
 
@@ -1003,7 +1008,7 @@ void requeue_futex(struct futex_q *q, struct futex_hash_bucket *hb1,
 		plist_add(&q->list, &hb2->chain);
 		q->lock_ptr = &hb2->lock;
 #ifdef CONFIG_DEBUG_PI_LIST
-		q->list.plist.lock = &hb2->lock;
+		q->list.plist.spinlock = &hb2->lock;
 #endif
 	}
 	get_futex_key_refs(key2);
@@ -1028,7 +1033,6 @@ 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;
 
@@ -1040,7 +1044,7 @@ void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key,
 
 	q->lock_ptr = &hb->lock;
 #ifdef CONFIG_DEBUG_PI_LIST
-	q->list.plist.lock = &hb->lock;
+	q->list.plist.spinlock = &hb->lock;
 #endif
 
 	wake_up_state(q->task, TASK_NORMAL);
@@ -1169,11 +1173,10 @@ retry:
 		pi_state = NULL;
 	}
 
-	ret = get_futex_key(uaddr1, fshared, &key1, VERIFY_READ);
+	ret = get_futex_key(uaddr1, fshared, &key1);
 	if (unlikely(ret != 0))
 		goto out;
-	ret = get_futex_key(uaddr2, fshared, &key2,
-			    requeue_pi ? VERIFY_WRITE : VERIFY_READ);
+	ret = get_futex_key(uaddr2, fshared, &key2);
 	if (unlikely(ret != 0))
 		goto out_put_key1;
 
@@ -1226,6 +1229,7 @@ retry_private:
 		 */
 		if (ret == 1) {
 			WARN_ON(pi_state);
+			drop_count++;
 			task_count++;
 			ret = get_futex_value_locked(&curval2, uaddr2);
 			if (!ret)
@@ -1304,6 +1308,7 @@ retry_private:
 			if (ret == 1) {
 				/* We got the lock. */
 				requeue_pi_wake_futex(this, &key2, hb2);
+				drop_count++;
 				continue;
 			} else if (ret) {
 				/* -EDEADLK */
@@ -1386,7 +1391,7 @@ static inline void queue_me(struct futex_q *q, struct futex_hash_bucket *hb)
 
 	plist_node_init(&q->list, prio);
 #ifdef CONFIG_DEBUG_PI_LIST
-	q->list.plist.lock = &hb->lock;
+	q->list.plist.spinlock = &hb->lock;
 #endif
 	plist_add(&q->list, &hb->chain);
 	q->task = current;
@@ -1521,18 +1526,18 @@ retry:
 	 * itself.
 	 */
 	if (pi_state->owner != NULL) {
-		spin_lock_irq(&pi_state->owner->pi_lock);
+		raw_spin_lock_irq(&pi_state->owner->pi_lock);
 		WARN_ON(list_empty(&pi_state->list));
 		list_del_init(&pi_state->list);
-		spin_unlock_irq(&pi_state->owner->pi_lock);
+		raw_spin_unlock_irq(&pi_state->owner->pi_lock);
 	}
 
 	pi_state->owner = newowner;
 
-	spin_lock_irq(&newowner->pi_lock);
+	raw_spin_lock_irq(&newowner->pi_lock);
 	WARN_ON(!list_empty(&pi_state->list));
 	list_add(&pi_state->list, &newowner->pi_state_list);
-	spin_unlock_irq(&newowner->pi_lock);
+	raw_spin_unlock_irq(&newowner->pi_lock);
 	return 0;
 
 	/*
@@ -1656,6 +1661,12 @@ 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);
 
@@ -1724,7 +1735,7 @@ static int futex_wait_setup(u32 __user *uaddr, u32 val, int fshared,
 	 */
 retry:
 	q->key = FUTEX_KEY_INIT;
-	ret = get_futex_key(uaddr, fshared, &q->key, VERIFY_READ);
+	ret = get_futex_key(uaddr, fshared, &q->key);
 	if (unlikely(ret != 0))
 		return ret;
 
@@ -1785,6 +1796,7 @@ 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 +1814,14 @@ 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;
@@ -1884,7 +1901,7 @@ static int futex_lock_pi(u32 __user *uaddr, int fshared,
 	q.requeue_pi_key = NULL;
 retry:
 	q.key = FUTEX_KEY_INIT;
-	ret = get_futex_key(uaddr, fshared, &q.key, VERIFY_WRITE);
+	ret = get_futex_key(uaddr, fshared, &q.key);
 	if (unlikely(ret != 0))
 		goto out;
 
@@ -2003,7 +2020,7 @@ retry:
 	if ((uval & FUTEX_TID_MASK) != task_pid_vnr(current))
 		return -EPERM;
 
-	ret = get_futex_key(uaddr, fshared, &key, VERIFY_WRITE);
+	ret = get_futex_key(uaddr, fshared, &key);
 	if (unlikely(ret != 0))
 		goto out;
 
@@ -2111,11 +2128,12 @@ int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb,
 		 * Unqueue the futex_q and determine which it was.
 		 */
 		plist_del(&q->list, &q->list.plist);
-		drop_futex_key_refs(&q->key);
 
+		/* Handle spurious wakeups gracefully */
+		ret = -EWOULDBLOCK;
 		if (timeout && !timeout->task)
 			ret = -ETIMEDOUT;
-		else
+		else if (signal_pending(current))
 			ret = -ERESTARTNOINTR;
 	}
 	return ret;
@@ -2194,7 +2212,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared,
 	rt_waiter.task = NULL;
 
 	key2 = FUTEX_KEY_INIT;
-	ret = get_futex_key(uaddr2, fshared, &key2, VERIFY_WRITE);
+	ret = get_futex_key(uaddr2, fshared, &key2);
 	if (unlikely(ret != 0))
 		goto out;