padata: Block until the instance is unused on stop

This patch makes padata_stop to block until the padata
instance is unused. Also we split padata_stop to a locked
and a unlocked version. This is in preparation to be able
to change the cpumask after a call to patata stop.

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 e7d723a..9e18dfa 100644 (file)
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -490,6 +490,20 @@ static void __padata_start(struct padata_instance *pinst)
        pinst->flags |= PADATA_INIT;
 }
 
+static void __padata_stop(struct padata_instance *pinst)
+{
+       if (!(pinst->flags & PADATA_INIT))
+               return;
+
+       pinst->flags &= ~PADATA_INIT;
+
+       synchronize_rcu();
+
+       get_online_cpus();
+       padata_flush_queues(pinst->pd);
+       put_online_cpus();
+}
+
 /* Replace the internal control stucture with a new one. */
 static void padata_replace(struct padata_instance *pinst,
                           struct parallel_data *pd_new)
@@ -649,7 +663,7 @@ EXPORT_SYMBOL(padata_start);
 void padata_stop(struct padata_instance *pinst)
 {
        mutex_lock(&pinst->lock);
-       pinst->flags &= ~PADATA_INIT;
+       __padata_stop(pinst);
        mutex_unlock(&pinst->lock);
 }
 EXPORT_SYMBOL(padata_stop);
@@ -770,17 +784,11 @@ EXPORT_SYMBOL(padata_alloc);
  */
 void padata_free(struct padata_instance *pinst)
 {
-       padata_stop(pinst);
-
-       synchronize_rcu();
-
 #ifdef CONFIG_HOTPLUG_CPU
        unregister_hotcpu_notifier(&pinst->cpu_notifier);
 #endif
-       get_online_cpus();
-       padata_flush_queues(pinst->pd);
-       put_online_cpus();
 
+       padata_stop(pinst);
        padata_free_pd(pinst->pd);
        free_cpumask_var(pinst->cpumask);
        kfree(pinst);