padata: get_next is never NULL

Per Dan's static checker warning, the code that returns NULL was removed
in 2010, so this patch updates the comments and fixes the code
assumptions.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

kernel/padata.c

@@ -154,8 +154,6 @@ EXPORT_SYMBOL(padata_do_parallel);
  * A pointer to the control struct of the next object that needs
  * serialization, if present in one of the percpu reorder queues.
  *
- * NULL, if all percpu reorder queues are empty.
- *
  * -EINPROGRESS, if the next object that needs serialization will
  *  be parallel processed by another cpu and is not yet present in
  *  the cpu's reorder queue.
@@ -182,8 +180,6 @@ static struct padata_priv *padata_get_next(struct parallel_data *pd)
 	cpu = padata_index_to_cpu(pd, next_index);
 	next_queue = per_cpu_ptr(pd->pqueue, cpu);
 
-	padata = NULL;
-
 	reorder = &next_queue->reorder;
 
 	spin_lock(&reorder->lock);
@@ -235,12 +231,11 @@ static void padata_reorder(struct parallel_data *pd)
 		padata = padata_get_next(pd);
 
 		/*
-		 * All reorder queues are empty, or the next object that needs
-		 * serialization is parallel processed by another cpu and is
-		 * still on it's way to the cpu's reorder queue, nothing to
-		 * do for now.
+		 * If the next object that needs serialization is parallel
+		 * processed by another cpu and is still on it's way to the
+		 * cpu's reorder queue, nothing to do for now.
 		 */
-		if (!padata || PTR_ERR(padata) == -EINPROGRESS)
+		if (PTR_ERR(padata) == -EINPROGRESS)
 			break;
 
 		/*