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Commit d07355f5 authored by Dmitry Adamushko's avatar Dmitry Adamushko Committed by Ingo Molnar
Browse files

sched: check for SD_SERIALIZE atomically in rebalance_domains() 



Nothing really serious here, mainly just a matter of nit-picking :-/

From: Dmitry Adamushko <dmitry.adamushko@gmail.com>
For CONFIG_SCHED_DEBUG && CONFIG_SYSCT configs, sd->flags can be altered
while being manipulated in rebalance_domains(). Let's do an atomic check.
We rely here on the atomicity of read/write accesses for aligned words.

Signed-off-by: default avatarDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 6d299f1b

kernel/sched.c

+4 −2
Original line number Diff line number Diff line
@@ -3668,6 +3668,7 @@ static void rebalance_domains(int cpu, enum cpu_idle_type idle) 
	/* Earliest time when we have to do rebalance again */

	unsigned long next_balance = jiffies + 60*HZ;

	int update_next_balance = 0;

	int need_serialize;

	cpumask_t tmp;



	for_each_domain(cpu, sd) {
@@ -3685,8 +3686,9 @@ static void rebalance_domains(int cpu, enum cpu_idle_type idle) 
		if (interval > HZ*NR_CPUS/10)

			interval = HZ*NR_CPUS/10;



		need_serialize = sd->flags & SD_SERIALIZE;



		if (sd->flags & SD_SERIALIZE) {

		if (need_serialize) {

			if (!spin_trylock(&balancing))

				goto out;

		}
@@ -3702,7 +3704,7 @@ static void rebalance_domains(int cpu, enum cpu_idle_type idle) 
			}

			sd->last_balance = jiffies;

		}

		if (sd->flags & SD_SERIALIZE)

		if (need_serialize)

			spin_unlock(&balancing);

out:

		if (time_after(next_balance, sd->last_balance + interval)) {