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sched/core: Check for available DL bandwidth in cpuset_cpu_inactive()

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Hotplug operations are destructive w.r.t. cpusets. In case such an
operation is performed on a CPU belonging to an exlusive cpuset, the
DL bandwidth information associated with the corresponding root
domain is gone even if the operation fails (in sched_cpu_inactive()).

For this reason we need to move the check we currently have in
sched_cpu_inactive() to cpuset_cpu_inactive() to prevent useless
cpusets reconfiguration in the CPU_DOWN_FAILED path.

Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@gmail.com>
Link: http://lkml.kernel.org/r/1427792017-7356-2-git-send-email-juri.lelli@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Juri Lelli 2015-03-31 09:53:37 +01:00 committed by Ingo Molnar
parent 4cd57f9713
commit 3c18d447b3
1 changed files with 28 additions and 28 deletions
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56
kernel/sched/core.c
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@ -5337,36 +5337,13 @@ static int sched_cpu_active(struct notifier_block *nfb,
static int sched_cpu_inactive(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
unsigned long flags;
long cpu = (long)hcpu;
struct dl_bw *dl_b;
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_DOWN_PREPARE:
set_cpu_active(cpu, false);
/* explicitly allow suspend */
if (!(action & CPU_TASKS_FROZEN)) {
bool overflow;
int cpus;
rcu_read_lock_sched();
dl_b = dl_bw_of(cpu);
raw_spin_lock_irqsave(&dl_b->lock, flags);
cpus = dl_bw_cpus(cpu);
overflow = __dl_overflow(dl_b, cpus, 0, 0);
raw_spin_unlock_irqrestore(&dl_b->lock, flags);
rcu_read_unlock_sched();
if (overflow)
return notifier_from_errno(-EBUSY);
}
set_cpu_active((long)hcpu, false);
return NOTIFY_OK;
default:
return NOTIFY_DONE;
}
return NOTIFY_DONE;
}
static int __init migration_init(void)
@ -7006,7 +6983,6 @@ static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
*/
case CPU_ONLINE:
case CPU_DOWN_FAILED:
cpuset_update_active_cpus(true);
break;
default:
@ -7018,8 +6994,32 @@ static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
void *hcpu)
{
switch (action) {
unsigned long flags;
long cpu = (long)hcpu;
struct dl_bw *dl_b;
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_DOWN_PREPARE:
/* explicitly allow suspend */
if (!(action & CPU_TASKS_FROZEN)) {
bool overflow;
int cpus;
rcu_read_lock_sched();
dl_b = dl_bw_of(cpu);
raw_spin_lock_irqsave(&dl_b->lock, flags);
cpus = dl_bw_cpus(cpu);
overflow = __dl_overflow(dl_b, cpus, 0, 0);
raw_spin_unlock_irqrestore(&dl_b->lock, flags);
rcu_read_unlock_sched();
if (overflow) {
trace_printk("hotplug failed for cpu %lu", cpu);
return notifier_from_errno(-EBUSY);
}
}
cpuset_update_active_cpus(false);
break;
case CPU_DOWN_PREPARE_FROZEN: