net: hns3: fix debugfs concurrency issue between kfree buffer and read

Now in hns3_dbg_uninit(), there may be concurrency between
kfree buffer and read, it may result in memory error.

Moving debugfs_remove_recursive() in front of kfree buffer to ensure
they don't happen at the same time.

Fixes: 5e69ea7e ("net: hns3: refactor the debugfs process")
Signed-off-by: NHao Chen <chenhao418@huawei.com>
Signed-off-by: NJijie Shao <shaojijie@huawei.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c

@@ -1415,9 +1415,9 @@ int hns3_dbg_init(struct hnae3_handle *handle)
 	return 0;
 
 out:
-	mutex_destroy(&handle->dbgfs_lock);
 	debugfs_remove_recursive(handle->hnae3_dbgfs);
 	handle->hnae3_dbgfs = NULL;
+	mutex_destroy(&handle->dbgfs_lock);
 	return ret;
 }
 
@@ -1425,6 +1425,9 @@ void hns3_dbg_uninit(struct hnae3_handle *handle)
 {
 	u32 i;
 
+	debugfs_remove_recursive(handle->hnae3_dbgfs);
+	handle->hnae3_dbgfs = NULL;
+
 	for (i = 0; i < ARRAY_SIZE(hns3_dbg_cmd); i++)
 		if (handle->dbgfs_buf[i]) {
 			kvfree(handle->dbgfs_buf[i]);
@@ -1432,8 +1435,6 @@ void hns3_dbg_uninit(struct hnae3_handle *handle)
 		}
 
 	mutex_destroy(&handle->dbgfs_lock);
-	debugfs_remove_recursive(handle->hnae3_dbgfs);
-	handle->hnae3_dbgfs = NULL;
 }
 
 void hns3_dbg_register_debugfs(const char *debugfs_dir_name)