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Subject[PATCH 7/8] padata: Flush the padata queues actively
yield was used to wait until all references of the internal control
structure in use are dropped before it is freed. This patch implements
padata_flush_queues which actively flushes the padata percpu queues
in this case.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
kernel/padata.c | 33 +++++++++++++++++++++++++--------
1 files changed, 25 insertions(+), 8 deletions(-)
diff --git a/kernel/padata.c b/kernel/padata.c
index 6d7ea48..ec6b8b7 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -417,6 +417,29 @@ static void padata_free_pd(struct parallel_data *pd)
kfree(pd);
}

+static void padata_flush_queues(struct parallel_data *pd)
+{
+ int cpu;
+ struct padata_queue *queue;
+
+ for_each_cpu(cpu, pd->cpumask) {
+ queue = per_cpu_ptr(pd->queue, cpu);
+ flush_work(&queue->pwork);
+ }
+
+ del_timer_sync(&pd->timer);
+
+ if (atomic_read(&pd->reorder_objects))
+ padata_reorder(pd);
+
+ for_each_cpu(cpu, pd->cpumask) {
+ queue = per_cpu_ptr(pd->queue, cpu);
+ flush_work(&queue->swork);
+ }
+
+ BUG_ON(atomic_read(&pd->refcnt) != 0);
+}
+
static void padata_replace(struct padata_instance *pinst,
struct parallel_data *pd_new)
{
@@ -428,11 +451,7 @@ static void padata_replace(struct padata_instance *pinst,

synchronize_rcu();

- while (atomic_read(&pd_old->refcnt) != 0)
- yield();
-
- flush_workqueue(pinst->wq);
-
+ padata_flush_queues(pd_old);
padata_free_pd(pd_old);

pinst->flags &= ~PADATA_RESET;
@@ -695,12 +714,10 @@ void padata_free(struct padata_instance *pinst)

synchronize_rcu();

- while (atomic_read(&pinst->pd->refcnt) != 0)
- yield();
-
#ifdef CONFIG_HOTPLUG_CPU
unregister_hotcpu_notifier(&pinst->cpu_notifier);
#endif
+ padata_flush_queues(pinst->pd);
padata_free_pd(pinst->pd);
free_cpumask_var(pinst->cpumask);
kfree(pinst);
--
1.5.6.5


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