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authorSteven Rostedt <rostedt@goodmis.org>2014-03-11 19:24:20 -0400
committerIngo Molnar <mingo@kernel.org>2014-03-12 10:48:59 +0100
commit383afd0971538b3d77532a56404b24cfe967b5dd (patch)
tree0ea584d122218bf5598b1c7a976c19e4fc272718 /kernel/sched
parent070826820daf423eee83ee4e90bf3daf2cdd85c2 (diff)
downloadop-kernel-dev-383afd0971538b3d77532a56404b24cfe967b5dd.zip
op-kernel-dev-383afd0971538b3d77532a56404b24cfe967b5dd.tar.gz
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.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9e126a2..ae365aa 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;
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