Fix the following Smatch complaint:
net/mptcp/pm_netlink.c:213 mptcp_pm_add_timer()
warn: variable dereferenced before check 'msk' (see line 208)
net/mptcp/pm_netlink.c
207 struct mptcp_sock *msk = entry->sock;
208 struct sock *sk = (struct sock *)msk;
209 struct net *net = sock_net(sk);
^^
"msk" dereferenced here.
210
211 pr_debug("msk=%p", msk);
212
213 if (!msk)
^^^^
Too late.
214 return;
215
Fixes: 93f323b9cccc ("mptcp: add a new sysctl add_addr_timeout")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Geliang Tang <geliangtang@xxxxxxxxx>
Reviewed-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>