1 files changed, 24 insertions, 8 deletions

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 7d208b2b1a19..37b48f63ae6a 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -135,6 +135,7 @@ int dm_table_create(struct dm_table **result, blk_mode_t mode,
 		return -ENOMEM;
 
 	INIT_LIST_HEAD(&t->devices);
+	init_rwsem(&t->devices_lock);
 
 	if (!num_targets)
 		num_targets = KEYS_PER_NODE;
@@ -359,16 +360,20 @@ int __ref dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode,
 	if (dev == disk_devt(t->md->disk))
 		return -EINVAL;
 
+	down_write(&t->devices_lock);
+
 	dd = find_device(&t->devices, dev);
 	if (!dd) {
 		dd = kmalloc(sizeof(*dd), GFP_KERNEL);
-		if (!dd)
-			return -ENOMEM;
+		if (!dd) {
+			r = -ENOMEM;
+			goto unlock_ret_r;
+		}
 
 		r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev);
 		if (r) {
 			kfree(dd);
-			return r;
+			goto unlock_ret_r;
 		}
 
 		refcount_set(&dd->count, 1);
@@ -378,12 +383,17 @@ int __ref dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode,
 	} else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) {
 		r = upgrade_mode(dd, mode, t->md);
 		if (r)
-			return r;
+			goto unlock_ret_r;
 	}
 	refcount_inc(&dd->count);
 out:
+	up_write(&t->devices_lock);
 	*result = dd->dm_dev;
 	return 0;
+
+unlock_ret_r:
+	up_write(&t->devices_lock);
+	return r;
 }
 EXPORT_SYMBOL(dm_get_device);
 
@@ -419,9 +429,12 @@ static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 void dm_put_device(struct dm_target *ti, struct dm_dev *d)
 {
 	int found = 0;
-	struct list_head *devices = &ti->table->devices;
+	struct dm_table *t = ti->table;
+	struct list_head *devices = &t->devices;
 	struct dm_dev_internal *dd;
 
+	down_write(&t->devices_lock);
+
 	list_for_each_entry(dd, devices, list) {
 		if (dd->dm_dev == d) {
 			found = 1;
@@ -430,14 +443,17 @@ void dm_put_device(struct dm_target *ti, struct dm_dev *d)
 	}
 	if (!found) {
 		DMERR("%s: device %s not in table devices list",
-		      dm_device_name(ti->table->md), d->name);
-		return;
+		      dm_device_name(t->md), d->name);
+		goto unlock_ret;
 	}
 	if (refcount_dec_and_test(&dd->count)) {
-		dm_put_table_device(ti->table->md, d);
+		dm_put_table_device(t->md, d);
 		list_del(&dd->list);
 		kfree(dd);
 	}
+
+unlock_ret:
+	up_write(&t->devices_lock);
 }
 EXPORT_SYMBOL(dm_put_device);