[PATCH 4.4 10/38] futex: Simplify fixup_pi_state_owner()

[Greg Kroah-Hartman]

From: Lee Jones <lee.jo...@linaro.org>

From: Thomas Gleixner <t...@linutronix.de>

[ Upstream commit f2dac39d93987f7de1e20b3988c8685523247ae2 ]

Too many gotos already and an upcoming fix would make it even more
unreadable.

Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: sta...@vger.kernel.org
Signed-off-by: Lee Jones <lee.jo...@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 kernel/futex.c |   41 +++++++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 14 deletions(-)

--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2237,18 +2237,16 @@ static void unqueue_me_pi(struct futex_q
        spin_unlock(q->lock_ptr);
 }
 
-static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
-                               struct task_struct *argowner)
+static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
+                                 struct task_struct *argowner)
 {
        struct futex_pi_state *pi_state = q->pi_state;
-       u32 uval, uninitialized_var(curval), newval;
        struct task_struct *oldowner, *newowner;
-       u32 newtid;
-       int ret;
-
-       lockdep_assert_held(q->lock_ptr);
+       u32 uval, curval, newval, newtid;
+       int err = 0;
 
        oldowner = pi_state->owner;
+
        /* Owner died? */
        if (!pi_state->owner)
                newtid |= FUTEX_OWNER_DIED;
@@ -2289,7 +2287,7 @@ retry:
 
                if (__rt_mutex_futex_trylock(&pi_state->pi_mutex)) {
                        /* We got the lock after all, nothing to fix. */
-                       return 0;
+                       return 1;
                }
 
                /*
@@ -2304,7 +2302,7 @@ retry:
                         * We raced against a concurrent self; things are
                         * already fixed up. Nothing to do.
                         */
-                       return 0;
+                       return 1;
                }
                newowner = argowner;
        }
@@ -2345,7 +2343,7 @@ retry:
 handle_fault:
        spin_unlock(q->lock_ptr);
 
-       ret = fault_in_user_writeable(uaddr);
+       err = fault_in_user_writeable(uaddr);
 
        spin_lock(q->lock_ptr);
 
@@ -2353,12 +2351,27 @@ handle_fault:
         * Check if someone else fixed it for us:
         */
        if (pi_state->owner != oldowner)
-               return 0;
+               return argowner == current;
+
+       /* Retry if err was -EAGAIN or the fault in succeeded */
+       if (!err)
+               goto retry;
 
-       if (ret)
-               return ret;
+       return err;
+}
+
+static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
+                               struct task_struct *argowner)
+{
+       struct futex_pi_state *pi_state = q->pi_state;
+       int ret;
+
+       lockdep_assert_held(q->lock_ptr);
 
-       goto retry;
+       raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
+       ret = __fixup_pi_state_owner(uaddr, q, argowner);
+       raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
+       return ret;
 }
 
 static long futex_wait_restart(struct restart_block *restart);