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Merge branch 'linus' into locking/core, to pick up fixes

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Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2019-02-28 07:50:39 +01:00
commit 0614621d89
768 changed files with 7468 additions and 3957 deletions
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32
kernel/futex.c
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@ -2217,11 +2217,11 @@ static inline struct futex_hash_bucket *queue_lock(struct futex_q *q)
* decrement the counter at queue_unlock() when some error has
* occurred and we don't end up adding the task to the list.
*/
hb_waiters_inc(hb);
hb_waiters_inc(hb); /* implies smp_mb(); (A) */
q->lock_ptr = &hb->lock;
spin_lock(&hb->lock); /* implies smp_mb(); (A) */
spin_lock(&hb->lock);
return hb;
}
@ -2857,35 +2857,39 @@ retry_private:
* and BUG when futex_unlock_pi() interleaves with this.
*
* Therefore acquire wait_lock while holding hb->lock, but drop the
* latter before calling rt_mutex_start_proxy_lock(). This still fully
* serializes against futex_unlock_pi() as that does the exact same
* lock handoff sequence.
* latter before calling __rt_mutex_start_proxy_lock(). This
* interleaves with futex_unlock_pi() -- which does a similar lock
* handoff -- such that the latter can observe the futex_q::pi_state
* before __rt_mutex_start_proxy_lock() is done.
*/
raw_spin_lock_irq(&q.pi_state->pi_mutex.wait_lock);
spin_unlock(q.lock_ptr);
/*
* __rt_mutex_start_proxy_lock() unconditionally enqueues the @rt_waiter
* such that futex_unlock_pi() is guaranteed to observe the waiter when
* it sees the futex_q::pi_state.
*/
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);
if (ret) {
if (ret == 1)
ret = 0;
spin_lock(q.lock_ptr);
goto no_block;
goto cleanup;
}
if (unlikely(to))
hrtimer_start_expires(&to->timer, HRTIMER_MODE_ABS);
ret = rt_mutex_wait_proxy_lock(&q.pi_state->pi_mutex, to, &rt_waiter);
cleanup:
spin_lock(q.lock_ptr);
/*
* If we failed to acquire the lock (signal/timeout), we must
* If we failed to acquire the lock (deadlock/signal/timeout), we must
* first acquire the hb->lock before removing the lock from the
* rt_mutex waitqueue, such that we can keep the hb and rt_mutex
* wait lists consistent.
* rt_mutex waitqueue, such that we can keep the hb and rt_mutex wait
* lists consistent.
*
* In particular; it is important that futex_unlock_pi() can not
* observe this inconsistency.
@ -3009,6 +3013,10 @@ retry:
* there is no point where we hold neither; and therefore
* wake_futex_pi() must observe a state consistent with what we
* observed.
*
* In particular; this forces __rt_mutex_start_proxy() to
* complete such that we're guaranteed to observe the
* rt_waiter. Also see the WARN in wake_futex_pi().
*/
raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
spin_unlock(&hb->lock);