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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 <lcapitulino@mandriva.com.br>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 09b56adc

kernel/sched.c

+9 −5
Original line number Diff line number Diff line
@@ -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 is 0 for SCHED_FIFO tasks and for SCHED_OTHER

	 * tasks that are on an otherwise idle runqueue:

	 */

	time_slice = 0;

	else if (p->policy == SCHED_RR)

	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);