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0782e63bc6
Ronny reported that the following scenario is not handled correctly: T1 (prio = 10) lock(rtmutex); T2 (prio = 20) lock(rtmutex) boost T1 T1 (prio = 20) sys_set_scheduler(prio = 30) T1 prio = 30 .... sys_set_scheduler(prio = 10) T1 prio = 30 The last step is wrong as T1 should now be back at prio 20. Commitc365c292d0("sched: Consider pi boosting in setscheduler()") only handles the case where a boosted tasks tries to lower its priority. Fix it by taking the new effective priority into account for the decision whether a change of the priority is required. Reported-by: Ronny Meeus <ronny.meeus@gmail.com> Tested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Cc: <stable@vger.kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Fixes:c365c292d0("sched: Consider pi boosting in setscheduler()") Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1505051806060.4225@nanos Signed-off-by: Ingo Molnar <mingo@kernel.org>
61 lines
1.3 KiB
C
61 lines
1.3 KiB
C
#ifndef _SCHED_RT_H
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#define _SCHED_RT_H
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#include <linux/sched/prio.h>
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static inline int rt_prio(int prio)
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{
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if (unlikely(prio < MAX_RT_PRIO))
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return 1;
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return 0;
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}
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static inline int rt_task(struct task_struct *p)
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{
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return rt_prio(p->prio);
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}
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#ifdef CONFIG_RT_MUTEXES
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extern int rt_mutex_getprio(struct task_struct *p);
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extern void rt_mutex_setprio(struct task_struct *p, int prio);
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extern int rt_mutex_get_effective_prio(struct task_struct *task, int newprio);
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extern struct task_struct *rt_mutex_get_top_task(struct task_struct *task);
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extern void rt_mutex_adjust_pi(struct task_struct *p);
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static inline bool tsk_is_pi_blocked(struct task_struct *tsk)
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{
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return tsk->pi_blocked_on != NULL;
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}
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#else
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static inline int rt_mutex_getprio(struct task_struct *p)
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{
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return p->normal_prio;
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}
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static inline int rt_mutex_get_effective_prio(struct task_struct *task,
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int newprio)
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{
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return newprio;
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}
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static inline struct task_struct *rt_mutex_get_top_task(struct task_struct *task)
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{
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return NULL;
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}
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# define rt_mutex_adjust_pi(p) do { } while (0)
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static inline bool tsk_is_pi_blocked(struct task_struct *tsk)
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{
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return false;
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}
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#endif
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extern void normalize_rt_tasks(void);
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/*
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* default timeslice is 100 msecs (used only for SCHED_RR tasks).
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* Timeslices get refilled after they expire.
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*/
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#define RR_TIMESLICE (100 * HZ / 1000)
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#endif /* _SCHED_RT_H */
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