From: Sebastian Andrzej Siewior Date: Wed, 26 Jun 2019 17:44:27 +0200 Subject: [PATCH 274/353] Revert "futex: workaround migrate_disable/enable in different context" Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=25adb203ce6bb1c640d6b4dd64c09a6566fbfd3f [ 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 Signed-off-by: Steven Rostedt (VMware) --- 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); /*