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From: Lee Jones <lee.jones@linaro.org>
To: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Lee Jones <lee.jones@linaro.org>
Subject: [PATCH 09/10] futex: Simplify fixup_pi_state_owner()
Date: Wed,  3 Feb 2021 13:45:38 +0000	[thread overview]
Message-ID: <20210203134539.2583943-10-lee.jones@linaro.org> (raw)
In-Reply-To: <20210203134539.2583943-1-lee.jones@linaro.org>

From: Thomas Gleixner <tglx@linutronix.de>

[ Upstream commit f2dac39d93987f7de1e20b3988c8685523247ae2 ]

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: Lee Jones <lee.jones@linaro.org>
---
 kernel/futex.c | 41 +++++++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 14 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index be5e3e927bffa..c163f5d6efab3 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2272,18 +2272,16 @@ 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)
 {
 	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;
@@ -2324,7 +2322,7 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
 
 		if (__rt_mutex_futex_trylock(&pi_state->pi_mutex)) {
 			/* We got the lock after all, nothing to fix. */
-			return 0;
+			return 1;
 		}
 
 		/*
@@ -2339,7 +2337,7 @@ 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.
 			 */
-			return 0;
+			return 1;
 		}
 		newowner = argowner;
 	}
@@ -2380,7 +2378,7 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
 handle_fault:
 	spin_unlock(q->lock_ptr);
 
-	ret = fault_in_user_writeable(uaddr);
+	err = fault_in_user_writeable(uaddr);
 
 	spin_lock(q->lock_ptr);
 
@@ -2388,12 +2386,27 @@ 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)
-		return 0;
+		return argowner == current;
 
-	if (ret)
-		return ret;
+	/* Retry if err was -EAGAIN or the fault in succeeded */
+	if (!err)
+		goto retry;
 
-	goto retry;
+	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);
+
+	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);
-- 
2.25.1


  parent reply	other threads:[~2021-02-03 13:48 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-03 13:45 [PATCH 4.9 00/10] [Set 2] Futex back-port Lee Jones
2021-02-03 13:45 ` [PATCH 01/10] futex,rt_mutex: Provide futex specific rt_mutex API Lee Jones
2021-02-03 13:45 ` [PATCH 02/10] futex: Remove rt_mutex_deadlock_account_*() Lee Jones
2021-02-03 13:45 ` [PATCH 03/10] futex: Rework inconsistent rt_mutex/futex_q state Lee Jones
2021-02-03 13:45 ` [PATCH 04/10] futex: Avoid violating the 10th rule of futex Lee Jones
2021-02-03 13:45 ` [PATCH 05/10] futex: Replace pointless printk in fixup_owner() Lee Jones
2021-02-03 13:45 ` [PATCH 06/10] futex: Provide and use pi_state_update_owner() Lee Jones
2021-02-03 13:45 ` [PATCH 07/10] rtmutex: Remove unused argument from rt_mutex_proxy_unlock() Lee Jones
2021-02-03 13:45 ` [PATCH 08/10] futex: Use pi_state_update_owner() in put_pi_state() Lee Jones
2021-02-03 13:45 ` Lee Jones [this message]
2021-02-03 13:45 ` [PATCH 10/10] futex: Handle faults correctly for PI futexes Lee Jones
2021-02-04 15:15 ` [PATCH 4.9 00/10] [Set 2] Futex back-port Greg KH
2021-02-04 17:28 [PATCH 4.4 " Lee Jones
2021-02-04 17:29 ` [PATCH 09/10] futex: Simplify fixup_pi_state_owner() Lee Jones

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