crypto: cryptd - Protect per-CPU resource by disabling BH.

index a1bea0f4baa88..668095eca0faf 100644
@@ -39,6 +39,10 @@ struct cryptd_cpu_queue {
 };
 
 struct cryptd_queue {
+	/*
+	 * Protected by disabling BH to allow enqueueing from softinterrupt and
+	 * dequeuing from kworker (cryptd_queue_worker()).
+	 */
 	struct cryptd_cpu_queue __percpu *cpu_queue;
 };
 

@@ -125,28 +129,28 @@ static void cryptd_fini_queue(struct cryptd_queue *queue)
 static int cryptd_enqueue_request(struct cryptd_queue *queue,
 				  struct crypto_async_request *request)
 {
-	int cpu, err;
+	int err;
 	struct cryptd_cpu_queue *cpu_queue;
 	refcount_t *refcnt;
 
-	cpu = get_cpu();
+	local_bh_disable();
 	cpu_queue = this_cpu_ptr(queue->cpu_queue);
 	err = crypto_enqueue_request(&cpu_queue->queue, request);
 
 	refcnt = crypto_tfm_ctx(request->tfm);
 
 	if (err == -ENOSPC)
-		goto out_put_cpu;
+		goto out;
 
-	queue_work_on(cpu, cryptd_wq, &cpu_queue->work);
+	queue_work_on(smp_processor_id(), cryptd_wq, &cpu_queue->work);
 
 	if (!refcount_read(refcnt))
-		goto out_put_cpu;
+		goto out;
 
 	refcount_inc(refcnt);
 
-out_put_cpu:
-	put_cpu();
+out:
+	local_bh_enable();
 
 	return err;
 }

@@ -162,15 +166,10 @@ static void cryptd_queue_worker(struct work_struct *work)
 	cpu_queue = container_of(work, struct cryptd_cpu_queue, work);
 	/*
 	 * Only handle one request at a time to avoid hogging crypto workqueue.
-	 * preempt_disable/enable is used to prevent being preempted by
-	 * cryptd_enqueue_request(). local_bh_disable/enable is used to prevent
-	 * cryptd_enqueue_request() being accessed from software interrupts.
 	 */
 	local_bh_disable();
-	preempt_disable();
 	backlog = crypto_get_backlog(&cpu_queue->queue);
 	req = crypto_dequeue_request(&cpu_queue->queue);
-	preempt_enable();
 	local_bh_enable();
 
 	if (!req)