futex: make futex_(get|put)_key() calls symmetric

Impact: cleanup

This patch makes the calls to futex_get_key_refs() and futex_drop_key_refs()
explicitly symmetric by only "putting" keys we successfully "got".  Also
cleanup a couple return points that didn't "put" after a successful "get".

Build and boot tested on an x86_64 system.

Signed-off-by: Darren Hart <dvhltc@us.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/futex.c b/kernel/futex.c
index b4f87bac91c1afb824404fe8fb6ce90d43669d41..c5ac55cc0c16036efa116d55149200388c6d3791 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -723,8 +723,8 @@ static int futex_wake(u32 __user *uaddr, int fshared, int nr_wake, u32 bitset)
        }
 
        spin_unlock(&hb->lock);
-out:
        put_futex_key(fshared, &key);
+out:
        return ret;
 }
 
@@ -748,7 +748,7 @@ retryfull:
                goto out;
        ret = get_futex_key(uaddr2, fshared, &key2);
        if (unlikely(ret != 0))
-               goto out;
+               goto out_put_key1;
 
        hb1 = hash_futex(&key1);
        hb2 = hash_futex(&key2);
@@ -770,12 +770,12 @@ retry:
                 * but we might get them from range checking
                 */
                ret = op_ret;
-               goto out;
+               goto out_put_keys;
 #endif
 
                if (unlikely(op_ret != -EFAULT)) {
                        ret = op_ret;
-                       goto out;
+                       goto out_put_keys;
                }
 
                /*
@@ -789,7 +789,7 @@ retry:
                        ret = futex_handle_fault((unsigned long)uaddr2,
                                                 attempt);
                        if (ret)
-                               goto out;
+                               goto out_put_keys;
                        goto retry;
                }
 
@@ -827,10 +827,11 @@ retry:
        spin_unlock(&hb1->lock);
        if (hb1 != hb2)
                spin_unlock(&hb2->lock);
-out:
+out_put_keys:
        put_futex_key(fshared, &key2);
+out_put_key1:
        put_futex_key(fshared, &key1);
-
+out:
        return ret;
 }
 
@@ -847,13 +848,13 @@ static int futex_requeue(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
        struct futex_q *this, *next;
        int ret, drop_count = 0;
 
- retry:
+retry:
        ret = get_futex_key(uaddr1, fshared, &key1);
        if (unlikely(ret != 0))
                goto out;
        ret = get_futex_key(uaddr2, fshared, &key2);
        if (unlikely(ret != 0))
-               goto out;
+               goto out_put_key1;
 
        hb1 = hash_futex(&key1);
        hb2 = hash_futex(&key2);
@@ -875,7 +876,7 @@ static int futex_requeue(u32 __user *uaddr1, int fshared, u32 __user *uaddr2,
                        if (!ret)
                                goto retry;
 
-                       return ret;
+                       goto out_put_keys;
                }
                if (curval != *cmpval) {
                        ret = -EAGAIN;
@@ -920,9 +921,11 @@ out_unlock:
        while (--drop_count >= 0)
                drop_futex_key_refs(&key1);
 
-out:
+out_put_keys:
        put_futex_key(fshared, &key2);
+out_put_key1:
        put_futex_key(fshared, &key1);
+out:
        return ret;
 }
 
@@ -983,7 +986,7 @@ static int unqueue_me(struct futex_q *q)
        int ret = 0;
 
        /* In the common case we don't take the spinlock, which is nice. */
- retry:
+retry:
        lock_ptr = q->lock_ptr;
        barrier();
        if (lock_ptr != NULL) {
@@ -1165,11 +1168,11 @@ static int futex_wait(u32 __user *uaddr, int fshared,
 
        q.pi_state = NULL;
        q.bitset = bitset;
- retry:
+retry:
        q.key = FUTEX_KEY_INIT;
        ret = get_futex_key(uaddr, fshared, &q.key);
        if (unlikely(ret != 0))
-               goto out_release_sem;
+               goto out;
 
        hb = queue_lock(&q);
 
@@ -1197,6 +1200,7 @@ static int futex_wait(u32 __user *uaddr, int fshared,
 
        if (unlikely(ret)) {
                queue_unlock(&q, hb);
+               put_futex_key(fshared, &q.key);
 
                ret = get_user(uval, uaddr);
 
@@ -1206,7 +1210,7 @@ static int futex_wait(u32 __user *uaddr, int fshared,
        }
        ret = -EWOULDBLOCK;
        if (uval != val)
-               goto out_unlock_release_sem;
+               goto out_unlock_put_key;
 
        /* Only actually queue if *uaddr contained val.  */
        queue_me(&q, hb);
@@ -1298,11 +1302,11 @@ static int futex_wait(u32 __user *uaddr, int fshared,
                return -ERESTART_RESTARTBLOCK;
        }
 
- out_unlock_release_sem:
+out_unlock_put_key:
        queue_unlock(&q, hb);
-
- out_release_sem:
        put_futex_key(fshared, &q.key);
+
+out:
        return ret;
 }
 
@@ -1351,16 +1355,16 @@ static int futex_lock_pi(u32 __user *uaddr, int fshared,
        }
 
        q.pi_state = NULL;
- retry:
+retry:
        q.key = FUTEX_KEY_INIT;
        ret = get_futex_key(uaddr, fshared, &q.key);
        if (unlikely(ret != 0))
-               goto out_release_sem;
+               goto out;
 
- retry_unlocked:
+retry_unlocked:
        hb = queue_lock(&q);
 
- retry_locked:
+retry_locked:
        ret = lock_taken = 0;
 
        /*
@@ -1381,14 +1385,14 @@ static int futex_lock_pi(u32 __user *uaddr, int fshared,
         */
        if (unlikely((curval & FUTEX_TID_MASK) == task_pid_vnr(current))) {
                ret = -EDEADLK;
-               goto out_unlock_release_sem;
+               goto out_unlock_put_key;
        }
 
        /*
         * Surprise - we got the lock. Just return to userspace:
         */
        if (unlikely(!curval))
-               goto out_unlock_release_sem;
+               goto out_unlock_put_key;
 
        uval = curval;
 
@@ -1424,7 +1428,7 @@ static int futex_lock_pi(u32 __user *uaddr, int fshared,
         * We took the lock due to owner died take over.
         */
        if (unlikely(lock_taken))
-               goto out_unlock_release_sem;
+               goto out_unlock_put_key;
 
        /*
         * We dont have the lock. Look up the PI state (or create it if
@@ -1463,7 +1467,7 @@ static int futex_lock_pi(u32 __user *uaddr, int fshared,
                                goto retry_locked;
                        }
                default:
-                       goto out_unlock_release_sem;
+                       goto out_unlock_put_key;
                }
        }
 
@@ -1554,16 +1558,17 @@ static int futex_lock_pi(u32 __user *uaddr, int fshared,
                destroy_hrtimer_on_stack(&to->timer);
        return ret != -EINTR ? ret : -ERESTARTNOINTR;
 
- out_unlock_release_sem:
+out_unlock_put_key:
        queue_unlock(&q, hb);
 
- out_release_sem:
+out_put_key:
        put_futex_key(fshared, &q.key);
+out:
        if (to)
                destroy_hrtimer_on_stack(&to->timer);
        return ret;
 
- uaddr_faulted:
+uaddr_faulted:
        /*
         * We have to r/w  *(int __user *)uaddr, and we have to modify it
         * atomically.  Therefore, if we continue to fault after get_user()
@@ -1576,7 +1581,7 @@ static int futex_lock_pi(u32 __user *uaddr, int fshared,
        if (attempt++) {
                ret = futex_handle_fault((unsigned long)uaddr, attempt);
                if (ret)
-                       goto out_release_sem;
+                       goto out_put_key;
                goto retry_unlocked;
        }
 
@@ -1668,9 +1673,9 @@ retry_unlocked:
 
 out_unlock:
        spin_unlock(&hb->lock);
-out:
        put_futex_key(fshared, &key);
 
+out:
        return ret;
 
 pi_faulted: