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Commit 2636ed5f authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched/rt: Avoid obvious configuration fail 



Setting the root group's cpu.rt_runtime_us to 0 is a bad thing; it
would disallow the kernel creating RT tasks.

One can of course still set it to 1, which will (likely) still wreck
your kernel, but at least make it clear that setting it to 0 is not
good.

Collect both sanity checks into the one place while we're there.

Suggested-by: default avatarZefan Li <lizefan@huawei.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20150209112715.GO24151@twins.programming.kicks-ass.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 1fe89e1b

kernel/sched/core.c

+11 −3
Original line number Diff line number Diff line
@@ -7675,6 +7675,17 @@ static int tg_set_rt_bandwidth(struct task_group *tg, 
{

	int i, err = 0;



	/*

	 * Disallowing the root group RT runtime is BAD, it would disallow the

	 * kernel creating (and or operating) RT threads.

	 */

	if (tg == &root_task_group && rt_runtime == 0)

		return -EINVAL;



	/* No period doesn't make any sense. */

	if (rt_period == 0)

		return -EINVAL;



	mutex_lock(&rt_constraints_mutex);

	read_lock(&tasklist_lock);

	err = __rt_schedulable(tg, rt_period, rt_runtime);
@@ -7731,9 +7742,6 @@ static int sched_group_set_rt_period(struct task_group *tg, long rt_period_us) 
	rt_period = (u64)rt_period_us * NSEC_PER_USEC;

	rt_runtime = tg->rt_bandwidth.rt_runtime;



	if (rt_period == 0)

		return -EINVAL;



	return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);

}