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From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org,
	linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Carsten Emde <C.Emde@osadl.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	John Kacur <jkacur@redhat.com>,
	Paul Gortmaker <paul.gortmaker@windriver.com>,
	Julia Cartwright <julia@ni.com>, Daniel Wagner <wagi@monom.org>,
	tom.zanussi@linux.intel.com
Subject: [PATCH RT 12/16] Revert "futex: workaround migrate_disable/enable in different context"
Date: Fri, 19 Jul 2019 17:49:43 -0400	[thread overview]
Message-ID: <20190719214957.919918275@goodmis.org> (raw)
In-Reply-To: 20190719214931.700049248@goodmis.org

4.19.59-rt24-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

[ Upstream commit a71221d81cc4873891ae44f3aa02df596079b786 ]

Drop the RT fixup, the futex code will be changed to avoid the need for
the workaround.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/futex.c | 19 -------------------
 1 file changed, 19 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 1d9423914bf4..54ffc25183ed 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2875,14 +2875,6 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags,
 	 * before __rt_mutex_start_proxy_lock() is done.
 	 */
 	raw_spin_lock_irq(&q.pi_state->pi_mutex.wait_lock);
-	/*
-	 * the migrate_disable() here disables migration in the in_atomic() fast
-	 * path which is enabled again in the following spin_unlock(). We have
-	 * one migrate_disable() pending in the slow-path which is reversed
-	 * after the raw_spin_unlock_irq() where we leave the atomic context.
-	 */
-	migrate_disable();
-
 	spin_unlock(q.lock_ptr);
 	/*
 	 * __rt_mutex_start_proxy_lock() unconditionally enqueues the @rt_waiter
@@ -2891,7 +2883,6 @@ static int futex_lock_pi(u32 __user *uaddr, unsigned int flags,
 	 */
 	ret = __rt_mutex_start_proxy_lock(&q.pi_state->pi_mutex, &rt_waiter, current);
 	raw_spin_unlock_irq(&q.pi_state->pi_mutex.wait_lock);
-	migrate_enable();
 
 	if (ret) {
 		if (ret == 1)
@@ -3040,21 +3031,11 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags)
 		 * rt_waiter. Also see the WARN in wake_futex_pi().
 		 */
 		raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
-		/*
-		 * Magic trickery for now to make the RT migrate disable
-		 * logic happy. The following spin_unlock() happens with
-		 * interrupts disabled so the internal migrate_enable()
-		 * won't undo the migrate_disable() which was issued when
-		 * locking hb->lock.
-		 */
-		migrate_disable();
 		spin_unlock(&hb->lock);
 
 		/* drops pi_state->pi_mutex.wait_lock */
 		ret = wake_futex_pi(uaddr, uval, pi_state);
 
-		migrate_enable();
-
 		put_pi_state(pi_state);
 
 		/*
-- 
2.20.1



  parent reply	other threads:[~2019-07-19 21:50 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-19 21:49 [PATCH RT 00/16] Linux 4.19.59-rt24-rc1 Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 01/16] kthread: add a global worker thread Steven Rostedt
2019-07-22  8:30   ` Juri Lelli
2019-07-23 18:54     ` Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 02/16] genirq: Do not invoke the affinity callback via a workqueue on RT Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 03/16] genirq: Handle missing work_struct in irq_set_affinity_notifier() Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 04/16] arm: imx6: cpuidle: Use raw_spinlock_t Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 05/16] rcu: Dont allow to change rcu_normal_after_boot on RT Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 06/16] pci/switchtec: fix stream_open.cocci warnings Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 07/16] sched/core: Drop a preempt_disable_rt() statement Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 08/16] timers: Redo the notification of canceling timers on -RT Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 09/16] Revert "futex: Ensure lock/unlock symetry versus pi_lock and hash bucket lock" Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 10/16] Revert "futex: Fix bug on when a requeued RT task times out" Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 11/16] Revert "rtmutex: Handle the various new futex race conditions" Steven Rostedt
2019-07-19 21:49 ` Steven Rostedt [this message]
2019-07-19 21:49 ` [PATCH RT 13/16] futex: Make the futex_hash_bucket lock raw Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 14/16] futex: Delay deallocation of pi_state Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 15/16] mm/zswap: Do not disable preemption in zswap_frontswap_store() Steven Rostedt
2019-07-19 21:49 ` [PATCH RT 16/16] Linux 4.19.59-rt24-rc1 Steven Rostedt

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