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Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fix from Thomas Gleixner: "A fix for a state leak which was introduced in the recent rework of futex/rtmutex interaction" * 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: futex,rt_mutex: Fix rt_mutex_cleanup_proxy_lock()
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commit
805f286907
1 changed files with 18 additions and 6 deletions
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@ -1785,12 +1785,14 @@ int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
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int ret;
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raw_spin_lock_irq(&lock->wait_lock);
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set_current_state(TASK_INTERRUPTIBLE);
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/* sleep on the mutex */
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set_current_state(TASK_INTERRUPTIBLE);
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ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter);
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/*
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* try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
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* have to fix that up.
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*/
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fixup_rt_mutex_waiters(lock);
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raw_spin_unlock_irq(&lock->wait_lock);
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return ret;
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@ -1821,16 +1823,26 @@ bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
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bool cleanup = false;
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raw_spin_lock_irq(&lock->wait_lock);
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/*
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* Do an unconditional try-lock, this deals with the lock stealing
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* state where __rt_mutex_futex_unlock() -> mark_wakeup_next_waiter()
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* sets a NULL owner.
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*
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* We're not interested in the return value, because the subsequent
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* test on rt_mutex_owner() will infer that. If the trylock succeeded,
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* we will own the lock and it will have removed the waiter. If we
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* failed the trylock, we're still not owner and we need to remove
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* ourselves.
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*/
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try_to_take_rt_mutex(lock, current, waiter);
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/*
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* Unless we're the owner; we're still enqueued on the wait_list.
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* So check if we became owner, if not, take us off the wait_list.
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*/
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if (rt_mutex_owner(lock) != current) {
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remove_waiter(lock, waiter);
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fixup_rt_mutex_waiters(lock);
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cleanup = true;
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}
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/*
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* try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
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* have to fix that up.
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