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-rw-r--r--block/blk-core.c10
-rw-r--r--block/elevator.c6
2 files changed, 15 insertions, 1 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 0c611d89d748..fce4b9387f36 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -741,9 +741,17 @@ blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
q->sg_reserved_size = INT_MAX;
+ /* Protect q->elevator from elevator_change */
+ mutex_lock(&q->sysfs_lock);
+
/* init elevator */
- if (elevator_init(q, NULL))
+ if (elevator_init(q, NULL)) {
+ mutex_unlock(&q->sysfs_lock);
return NULL;
+ }
+
+ mutex_unlock(&q->sysfs_lock);
+
return q;
}
EXPORT_SYMBOL(blk_init_allocated_queue);
diff --git a/block/elevator.c b/block/elevator.c
index 2bcbd8cc14d4..249cc5e10906 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -186,6 +186,12 @@ int elevator_init(struct request_queue *q, char *name)
struct elevator_type *e = NULL;
int err;
+ /*
+ * q->sysfs_lock must be held to provide mutual exclusion between
+ * elevator_switch() and here.
+ */
+ lockdep_assert_held(&q->sysfs_lock);
+
if (unlikely(q->elevator))
return 0;