elevator: Fix a race in elevator switching

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / block / cfq-iosched.c

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index d5cd3131c57a36645bcf049e28ab9a46ab5ea559..d5bbdcfd0dab5f56fa76f9ca08dc979fe16d1a35 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -4347,18 +4347,28 @@ static void cfq_exit_queue(struct elevator_queue *e)
        kfree(cfqd);
 }
 
-static int cfq_init_queue(struct request_queue *q)
+static int cfq_init_queue(struct request_queue *q, struct elevator_type *e)
 {
        struct cfq_data *cfqd;
        struct blkcg_gq *blkg __maybe_unused;
        int i, ret;
+       struct elevator_queue *eq;
+
+       eq = elevator_alloc(q, e);
+       if (!eq)
+               return -ENOMEM;
 
        cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
-       if (!cfqd)
+       if (!cfqd) {
+               kobject_put(&eq->kobj);
                return -ENOMEM;
+       }
+       eq->elevator_data = cfqd;
 
        cfqd->queue = q;
-       q->elevator->elevator_data = cfqd;
+       spin_lock_irq(q->queue_lock);
+       q->elevator = eq;
+       spin_unlock_irq(q->queue_lock);
 
        /* Init root service tree */
        cfqd->grp_service_tree = CFQ_RB_ROOT;
@@ -4433,6 +4443,7 @@ static int cfq_init_queue(struct request_queue *q)
 
 out_free:
        kfree(cfqd);
+       kobject_put(&eq->kobj);
        return ret;
 }