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>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/kernel/padata.c b/kernel/padata.c
index 6d7ea48..ec6b8b7 100644 (file)
--- 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);