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rtmutex: Fix more prio comparisons
There was a pure ->prio comparison left in try_to_wake_rt_mutex(), convert it to use rt_mutex_waiter_less(), noting that greater-or-equal is not-less (both in kernel priority view). This necessitated the introduction of cmp_task() which creates a pointer to an unnamed stack variable of struct rt_mutex_waiter type to compare against tasks. With this, we can now also create and employ rt_mutex_waiter_equal(). Reviewed-and-tested-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: juri.lelli@arm.com Cc: bigeasy@linutronix.de Cc: xlpang@redhat.com Cc: rostedt@goodmis.org Cc: mathieu.desnoyers@efficios.com Cc: jdesfossez@efficios.com Cc: bristot@redhat.com Link: http://lkml.kernel.org/r/20170323150216.455584638@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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@ -224,6 +224,12 @@ static inline bool unlock_rt_mutex_safe(struct rt_mutex *lock,
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}
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#endif
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/*
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* Only use with rt_mutex_waiter_{less,equal}()
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*/
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#define task_to_waiter(p) \
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&(struct rt_mutex_waiter){ .prio = (p)->prio, .deadline = (p)->dl.deadline }
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static inline int
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rt_mutex_waiter_less(struct rt_mutex_waiter *left,
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struct rt_mutex_waiter *right)
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@ -243,6 +249,25 @@ rt_mutex_waiter_less(struct rt_mutex_waiter *left,
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return 0;
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}
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static inline int
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rt_mutex_waiter_equal(struct rt_mutex_waiter *left,
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struct rt_mutex_waiter *right)
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{
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if (left->prio != right->prio)
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return 0;
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/*
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* If both waiters have dl_prio(), we check the deadlines of the
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* associated tasks.
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* If left waiter has a dl_prio(), and we didn't return 0 above,
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* then right waiter has a dl_prio() too.
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*/
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if (dl_prio(left->prio))
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return left->deadline == right->deadline;
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return 1;
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}
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static void
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rt_mutex_enqueue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter)
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{
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@ -553,7 +578,7 @@ static int rt_mutex_adjust_prio_chain(struct task_struct *task,
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* enabled we continue, but stop the requeueing in the chain
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* walk.
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*/
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if (waiter->prio == task->prio && !dl_task(task)) {
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if (rt_mutex_waiter_equal(waiter, task_to_waiter(task))) {
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if (!detect_deadlock)
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goto out_unlock_pi;
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else
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@ -856,7 +881,8 @@ static int try_to_take_rt_mutex(struct rt_mutex *lock, struct task_struct *task,
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* the top waiter priority (kernel view),
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* @task lost.
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*/
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if (task->prio >= rt_mutex_top_waiter(lock)->prio)
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if (!rt_mutex_waiter_less(task_to_waiter(task),
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rt_mutex_top_waiter(lock)))
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return 0;
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/*
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@ -1119,7 +1145,7 @@ void rt_mutex_adjust_pi(struct task_struct *task)
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raw_spin_lock_irqsave(&task->pi_lock, flags);
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waiter = task->pi_blocked_on;
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if (!waiter || (waiter->prio == task->prio && !dl_prio(task->prio))) {
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if (!waiter || rt_mutex_waiter_equal(waiter, task_to_waiter(task))) {
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raw_spin_unlock_irqrestore(&task->pi_lock, flags);
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return;
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}
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