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author | Steven Rostedt <rostedt@goodmis.org> | 2014-03-11 19:24:20 -0400 |
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committer | Ingo Molnar <mingo@kernel.org> | 2014-03-12 10:48:59 +0100 |
commit | 383afd0971538b3d77532a56404b24cfe967b5dd (patch) | |
tree | 0ea584d122218bf5598b1c7a976c19e4fc272718 /kernel/sched | |
parent | 070826820daf423eee83ee4e90bf3daf2cdd85c2 (diff) | |
download | linux-stable-383afd0971538b3d77532a56404b24cfe967b5dd.tar.gz linux-stable-383afd0971538b3d77532a56404b24cfe967b5dd.tar.bz2 linux-stable-383afd0971538b3d77532a56404b24cfe967b5dd.zip |
sched: Fix broken setscheduler()
I decided to run my tests on linux-next, and my wakeup_rt tracer was
broken. After running a bisect, I found that the problem commit was:
linux-next commit c365c292d059
"sched: Consider pi boosting in setscheduler()"
And the reason the wake_rt tracer test was failing, was because it had
no RT task to trace. I first noticed this when running with
sched_switch event and saw that my RT task still had normal SCHED_OTHER
priority. Looking at the problem commit, I found:
- p->normal_prio = normal_prio(p);
- p->prio = rt_mutex_getprio(p);
With no
+ p->normal_prio = normal_prio(p);
+ p->prio = rt_mutex_getprio(p);
Reading what the commit is suppose to do, I realize that the p->prio
can't be set if the task is boosted with a higher prio, but the
p->normal_prio still needs to be set regardless, otherwise, when the
task is deboosted, it wont get the new priority.
The p->prio has to be set before "check_class_changed()" is called,
otherwise the class wont be changed.
Also added fix to newprio to include a check for deadline policy that
was missing. This change was suggested by Juri Lelli.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: SebastianAndrzej Siewior <bigeasy@linutronix.de>
Cc: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140306120438.638bfe94@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r-- | kernel/sched/core.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9e126a21c5c7..ae365aaa8181 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3195,6 +3195,7 @@ static void __setscheduler_params(struct task_struct *p, * getparam()/getattr() don't report silly values for !rt tasks. */ p->rt_priority = attr->sched_priority; + p->normal_prio = normal_prio(p); set_load_weight(p); } @@ -3204,6 +3205,12 @@ static void __setscheduler(struct rq *rq, struct task_struct *p, { __setscheduler_params(p, attr); + /* + * If we get here, there was no pi waiters boosting the + * task. It is safe to use the normal prio. + */ + p->prio = normal_prio(p); + if (dl_prio(p->prio)) p->sched_class = &dl_sched_class; else if (rt_prio(p->prio)) @@ -3262,7 +3269,8 @@ static int __sched_setscheduler(struct task_struct *p, const struct sched_attr *attr, bool user) { - int newprio = MAX_RT_PRIO - 1 - attr->sched_priority; + int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 : + MAX_RT_PRIO - 1 - attr->sched_priority; int retval, oldprio, oldpolicy = -1, on_rq, running; int policy = attr->sched_policy; unsigned long flags; |