From 0782e63bc6fe7e2d3408d250df11d388b7799c6b Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 5 May 2015 19:49:49 +0200 Subject: sched: Handle priority boosted tasks proper in setscheduler() 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. Commit c365c292d059 ("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 Tested-by: Steven Rostedt Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Steven Rostedt Cc: Cc: Borislav Petkov Cc: H. Peter Anvin Cc: Mike Galbraith Fixes: c365c292d059 ("sched: Consider pi boosting in setscheduler()") Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1505051806060.4225@nanos Signed-off-by: Ingo Molnar --- include/linux/sched/rt.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'include') diff --git a/include/linux/sched/rt.h b/include/linux/sched/rt.h index 6341f5be6e24..a30b172df6e1 100644 --- a/include/linux/sched/rt.h +++ b/include/linux/sched/rt.h @@ -18,7 +18,7 @@ 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_check_prio(struct task_struct *task, int newprio); +extern int rt_mutex_get_effective_prio(struct task_struct *task, int newprio); extern struct task_struct *rt_mutex_get_top_task(struct task_struct *task); extern void rt_mutex_adjust_pi(struct task_struct *p); static inline bool tsk_is_pi_blocked(struct task_struct *tsk) @@ -31,9 +31,10 @@ static inline int rt_mutex_getprio(struct task_struct *p) return p->normal_prio; } -static inline int rt_mutex_check_prio(struct task_struct *task, int newprio) +static inline int rt_mutex_get_effective_prio(struct task_struct *task, + int newprio) { - return 0; + return newprio; } static inline struct task_struct *rt_mutex_get_top_task(struct task_struct *task) -- cgit v1.2.3