The reason here is that when the server tries to create a second link,
smc_llc_srv_add_link() has no protection and may add a new link to
link group. This breaks the security environment protected by
llc_conf_mutex.
Fixes: 2d2209f20189 ("net/smc: first part of add link processing as SMC server") Signed-off-by: D. Wythe <alibuda@linux.alibaba.com> Reviewed-by: Larysa Zaremba <larysa.zaremba@intel.com> Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>