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sched: check for SD_SERIALIZE atomically in rebalance_domains()

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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: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Dmitry Adamushko 2008-05-12 21:21:15 +02:00 committed by Ingo Molnar
parent 6d299f1b53
commit d07355f5de
1 changed files with 4 additions and 2 deletions
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6
kernel/sched.c
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@ -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)) {