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From 42f821c624f6605415eed76cbf5ece8a41b47ddf Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Wed, 26 Jun 2019 17:44:27 +0200
Subject: [PATCH 275/347] Revert "futex: workaround migrate_disable/enable in
different context"
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz
[ 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 bcd01b5a47df..9bcfdcffb2dd 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2998,14 +2998,6 @@ 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
@@ -3014,7 +3006,6 @@ 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)
@@ -3149,21 +3140,11 @@ 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);
/*
--
2.36.1
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