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sched/rtmutex: Refactor rt_mutex_setprio()

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With the introduction of SCHED_DEADLINE the whole notion that priority
is a single number is gone, therefore the @prio argument to
rt_mutex_setprio() doesn't make sense anymore.

So rework the code to pass a pi_task instead.

Note this also fixes a problem with pi_top_task caching; previously we
would not set the pointer (call rt_mutex_update_top_task) if the
priority didn't change, this could lead to a stale pointer.

As for the XXX, I think its fine to use pi_task->prio, because if it
differs from waiter->prio, a PI chain update is immenent.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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/20170323150216.303827095@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Peter Zijlstra
2017-03-23 15:56:11 +01:00
committed by Thomas Gleixner
parent aa2bfe5536
commit acd58620e4
3 changed files with 91 additions and 111 deletions
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24
include/linux/sched/rt.h
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@@ -18,28 +18,20 @@ static inline int rt_task(struct task_struct *p)
}
#ifdef CONFIG_RT_MUTEXES
extern int rt_mutex_getprio(struct task_struct *p);
extern void rt_mutex_setprio(struct task_struct *p, int prio);
extern int rt_mutex_get_effective_prio(struct task_struct *task, int newprio);
extern void rt_mutex_update_top_task(struct task_struct *p);
extern struct task_struct *rt_mutex_get_top_task(struct task_struct *task);
/*
* Must hold either p->pi_lock or task_rq(p)->lock.
*/
static inline struct task_struct *rt_mutex_get_top_task(struct task_struct *p)
{
return p->pi_top_task;
}
extern void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task);
extern void rt_mutex_adjust_pi(struct task_struct *p);
static inline bool tsk_is_pi_blocked(struct task_struct *tsk)
{
return tsk->pi_blocked_on != NULL;
}
#else
static inline int rt_mutex_getprio(struct task_struct *p)
{
return p->normal_prio;
}
static inline int rt_mutex_get_effective_prio(struct task_struct *task,
int newprio)
{
return newprio;
}
static inline struct task_struct *rt_mutex_get_top_task(struct task_struct *task)
{
return NULL;