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sched: fix crash in sys_sched_rr_get_interval()

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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: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2007-12-04 17:04:39 +01:00
parent 09b56adc98
commit 77034937dc
1 changed files with 9 additions and 5 deletions
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14
kernel/sched.c
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@ -4850,17 +4850,21 @@ long sys_sched_rr_get_interval(pid_t pid, struct timespec __user *interval)
if (retval)
goto out_unlock;
if (p->policy == SCHED_FIFO)
time_slice = 0;
else if (p->policy == SCHED_RR)
/*
* Time slice is 0 for SCHED_FIFO tasks and for SCHED_OTHER
* tasks that are on an otherwise idle runqueue:
*/
time_slice = 0;
if (p->policy == SCHED_RR) {
time_slice = DEF_TIMESLICE;
else {
} else {
struct sched_entity *se = &p->se;
unsigned long flags;
struct rq *rq;
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);
}
read_unlock(&tasklist_lock);