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From 55ea172ce3ebe276e734352eb1b236b3065496c3 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 19 Jan 2021 16:26:38 +0100
Subject: [PATCH] futex: Simplify fixup_pi_state_owner()
commit f2dac39d93987f7de1e20b3988c8685523247ae2 upstream
Too many gotos already and an upcoming fix would make it even more
unreadable.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/futex.c | 53 +++++++++++++++++++++++++-------------------------
1 file changed, 26 insertions(+), 27 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index 758deac71345..48c37ff4388d 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2462,18 +2462,13 @@ static void unqueue_me_pi(struct futex_q *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)
{
+ u32 uval, uninitialized_var(curval), newval, newtid;
struct futex_pi_state *pi_state = q->pi_state;
- u32 uval, uninitialized_var(curval), newval;
struct task_struct *oldowner, *newowner;
- u32 newtid;
- int ret, err = 0;
-
- lockdep_assert_held(q->lock_ptr);
-
- raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
+ int err = 0;
oldowner = pi_state->owner;
@@ -2507,14 +2502,12 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
* We raced against a concurrent self; things are
* already fixed up. Nothing to do.
*/
- ret = 0;
- goto out_unlock;
+ return 0;
}
if (__rt_mutex_futex_trylock(&pi_state->pi_mutex)) {
/* We got the lock. pi_state is correct. Tell caller. */
- ret = 1;
- goto out_unlock;
+ return 1;
}
/*
@@ -2541,8 +2534,7 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
* We raced against a concurrent self; things are
* already fixed up. Nothing to do.
*/
- ret = 1;
- goto out_unlock;
+ return 1;
}
newowner = argowner;
}
@@ -2573,7 +2565,6 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
* itself.
*/
pi_state_update_owner(pi_state, newowner);
- raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
return argowner == current;
@@ -2596,17 +2587,16 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
switch (err) {
case -EFAULT:
- ret = fault_in_user_writeable(uaddr);
+ err = fault_in_user_writeable(uaddr);
break;
case -EAGAIN:
cond_resched();
- ret = 0;
+ err = 0;
break;
default:
WARN_ON_ONCE(1);
- ret = err;
break;
}
@@ -2616,17 +2606,26 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
/*
* Check if someone else fixed it for us:
*/
- if (pi_state->owner != oldowner) {
- ret = argowner == current;
- goto out_unlock;
- }
+ if (pi_state->owner != oldowner)
+ return argowner == current;
- if (ret)
- goto out_unlock;
+ /* Retry if err was -EAGAIN or the fault in succeeded */
+ if (!err)
+ goto retry;
- goto retry;
+ return err;
+}
-out_unlock:
+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);
+
+ 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;
}
--
2.17.1
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