The risks are very high to provide free WiFi domestically. First of all, there is the policy risk. If you only provide a channel and do not operate applications that snatch other people's business such as VoIP, there probably won't be much problem. But being cautious doesn't hurt.
Last year, there was a free lunch of FON for WiFi abroad. Now we can also enjoy it domestically. A domestic company has recently released its WiFi Commune - Huoju Commune: www.hoju.cn.