futex: clean up futex_(un)lock_pi fault handling

[safe/jmp/linux-2.6] / kernel / futex.c

diff --git a/kernel/futex.c b/kernel/futex.c
index 99f8acc..b4f87ba 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1565,12 +1565,11 @@ static int futex_lock_pi(u32 __user *uaddr, int fshared,
 
  uaddr_faulted:
        /*
-        * We have to r/w  *(int __user *)uaddr, but we can't modify it
-        * non-atomically.  Therefore, if get_user below is not
-        * enough, we need to handle the fault ourselves, while
-        * still holding the mmap_sem.
-        *
-        * ... and hb->lock. :-) --ANK
+        * We have to r/w  *(int __user *)uaddr, and we have to modify it
+        * atomically.  Therefore, if we continue to fault after get_user()
+        * below, we need to handle the fault ourselves, while still holding
+        * the mmap_sem.  This can occur if the uaddr is under contention as
+        * we have to drop the mmap_sem in order to call get_user().
         */
        queue_unlock(&q, hb);
 
@@ -1582,7 +1581,7 @@ static int futex_lock_pi(u32 __user *uaddr, int fshared,
        }
 
        ret = get_user(uval, uaddr);
-       if (!ret && (uval != -EFAULT))
+       if (!ret)
                goto retry;
 
        if (to)
@@ -1676,12 +1675,11 @@ out:
 
 pi_faulted:
        /*
-        * We have to r/w  *(int __user *)uaddr, but we can't modify it
-        * non-atomically.  Therefore, if get_user below is not
-        * enough, we need to handle the fault ourselves, while
-        * still holding the mmap_sem.
-        *
-        * ... and hb->lock. --ANK
+        * We have to r/w  *(int __user *)uaddr, and we have to modify it
+        * atomically.  Therefore, if we continue to fault after get_user()
+        * below, we need to handle the fault ourselves, while still holding
+        * the mmap_sem.  This can occur if the uaddr is under contention as
+        * we have to drop the mmap_sem in order to call get_user().
         */
        spin_unlock(&hb->lock);
 
@@ -1694,7 +1692,7 @@ pi_faulted:
        }
 
        ret = get_user(uval, uaddr);
-       if (!ret && (uval != -EFAULT))
+       if (!ret)
                goto retry;
 
        return ret;