Previous patches changed the meaning of the return value of
rt_mutex_slowunlock(); update comments and code to reflect this.
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
kernel/futex.c | 12 ++++++------
kernel/locking/rtmutex.c | 20 +++++++++-----------
kernel/locking/rtmutex_common.h | 2 +-
3 files changed, 16 insertions(+), 18 deletions(-)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1261,7 +1261,7 @@ static int wake_futex_pi(u32 __user *uad
struct futex_pi_state *pi_state = this->pi_state;
u32 uninitialized_var(curval), newval;
WAKE_Q(wake_q);
- bool deboost;
+ bool postunlock;
int ret = 0;
if (!pi_state)
@@ -1327,17 +1327,17 @@ static int wake_futex_pi(u32 __user *uad
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
- deboost = rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q);
+ postunlock = rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q);
/*
* First unlock HB so the waiter does not spin on it once he got woken
- * up. Second wake up the waiter before the priority is adjusted. If we
- * deboost first (and lose our higher priority), then the task might get
- * scheduled away before the wake up can take place.
+ * up. Then wakeup the waiter by calling rt_mutex_postunlock(). Priority
+ * is already adjusted and preemption is disabled to avoid inversion.
*/
spin_unlock(&hb->lock);
- rt_mutex_postunlock(&wake_q, deboost);
+ if (postunlock)
+ rt_mutex_postunlock(&wake_q);
return 0;
}
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1254,7 +1254,8 @@ static inline int rt_mutex_slowtrylock(s
/*
* Slow path to release a rt-mutex.
- * Return whether the current task needs to undo a potential priority boosting.
+ *
+ * Return whether the current task needs to call rt_mutex_postunlock().
*/
static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock,
struct wake_q_head *wake_q)
@@ -1327,7 +1328,7 @@ static bool __sched rt_mutex_slowunlock(
raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
- /* check PI boosting */
+ /* call rt_mutex_postunlock() */
return true;
}
@@ -1378,15 +1379,14 @@ rt_mutex_fasttrylock(struct rt_mutex *lo
}
/*
- * Undo pi boosting (if necessary) and wake top waiter.
+ * Performs the wakeup of the the top-waiter and re-enables preemption.
*/
-void rt_mutex_postunlock(struct wake_q_head *wake_q, bool deboost)
+void rt_mutex_postunlock(struct wake_q_head *wake_q)
{
wake_up_q(wake_q);
/* Pairs with preempt_disable() in rt_mutex_slowunlock() */
- if (deboost)
- preempt_enable();
+ preempt_enable();
}
/**
@@ -1489,9 +1489,8 @@ void __sched rt_mutex_unlock(struct rt_m
rt_mutex_deadlock_account_unlock(current);
} else {
- bool deboost = rt_mutex_slowunlock(lock, &wake_q);
-
- rt_mutex_postunlock(&wake_q, deboost);
+ if (rt_mutex_slowunlock(lock, &wake_q))
+ rt_mutex_postunlock(&wake_q);
}
}
EXPORT_SYMBOL_GPL(rt_mutex_unlock);
@@ -1500,8 +1499,7 @@ EXPORT_SYMBOL_GPL(rt_mutex_unlock);
* rt_mutex_futex_unlock - Futex variant of rt_mutex_unlock
* @lock: the rt_mutex to be unlocked
*
- * Returns: true/false indicating whether priority adjustment is
- * required or not.
+ * Returns: true/false indicating whether we should call rt_mutex_postunlock().
*/
bool __sched rt_mutex_futex_unlock(struct rt_mutex *lock,
struct wake_q_head *wqh)
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -111,7 +111,7 @@ extern int rt_mutex_finish_proxy_lock(st
extern int rt_mutex_timed_futex_lock(struct rt_mutex *l, struct
hrtimer_sleeper *to);
extern bool rt_mutex_futex_unlock(struct rt_mutex *lock,
struct wake_q_head *wqh);
-extern void rt_mutex_postunlock(struct wake_q_head *wake_q, bool deboost);
+extern void rt_mutex_postunlock(struct wake_q_head *wake_q);
extern void rt_mutex_adjust_prio(struct task_struct *task);
#ifdef CONFIG_DEBUG_RT_MUTEXES
