Commit 77034937 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

sched: fix crash in sys_sched_rr_get_interval()

Luiz Fernando N. Capitulino reported that sched_rr_get_interval()
crashes for SCHED_OTHER tasks that are on an idle runqueue.

The fix is to return a 0 timeslice for tasks that are on an idle
runqueue. (and which are not running, obviously)

this also shrinks the code a bit:

   text    data     bss     dec     hex filename
  47903    3934     336   52173    cbcd sched.o.before
  47885    3934     336   52155    cbbb sched.o.after
Reported-by: default avatarLuiz Fernando N. Capitulino <>
Signed-off-by: default avatarIngo Molnar <>
parent 09b56adc
...@@ -4850,17 +4850,21 @@ long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval) ...@@ -4850,17 +4850,21 @@ long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval)
if (retval) if (retval)
goto out_unlock; goto out_unlock;
if (p->policy == SCHED_FIFO) /*
time_slice = 0; * Time slice is 0 for SCHED_FIFO tasks and for SCHED_OTHER
else if (p->policy == SCHED_RR) * tasks that are on an otherwise idle runqueue:
time_slice = 0;
if (p->policy == SCHED_RR) {
time_slice = DEF_TIMESLICE; time_slice = DEF_TIMESLICE;
else { } else {
struct sched_entity *se = &p->se; struct sched_entity *se = &p->se;
unsigned long flags; unsigned long flags;
struct rq *rq; struct rq *rq;
rq = task_rq_lock(p, &flags); rq = task_rq_lock(p, &flags);
time_slice = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se)); if (rq->cfs.load.weight)
time_slice = NS_TO_JIFFIES(sched_slice(&rq->cfs, se));
task_rq_unlock(rq, &flags); task_rq_unlock(rq, &flags);
} }
read_unlock(&tasklist_lock); read_unlock(&tasklist_lock);
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