mptcp: Do not lock in tcp_get_info for MPTCP_INFO

Because, we are already holding the meta-lock. If we are coming from mptcp_del_sock, we even are in bh-context and thus can't call lock_sock(). Fixes: 0b4d84d ("mptcp: Get MPTCP_INFO") Signed-off-by: Christoph Paasch <[email protected]> Signed-off-by: Matthieu Baerts <[email protected]>
multipath-tcp · Mar 8, 2019 · bd9b7a1 · bd9b7a1
1 parent 95520ec
commit bd9b7a1
Show file tree

Hide file tree

Showing 4 changed files with 12 additions and 9 deletions.
diff --git a/include/net/tcp.h b/include/net/tcp.h
@@ -749,7 +749,7 @@ static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
 }
 
 /* tcp.c */
-void tcp_get_info(struct sock *, struct tcp_info *);
+void tcp_get_info(struct sock *, struct tcp_info *, bool no_lock);
 
 /* Read 'sendfile()'-style from a TCP socket */
 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
@@ -3279,7 +3279,7 @@ static void tcp_get_info_chrono_stats(const struct tcp_sock *tp,
 }
 
 /* Return information about state of tcp endpoint in API format. */
-void tcp_get_info(struct sock *sk, struct tcp_info *info)
+void tcp_get_info(struct sock *sk, struct tcp_info *info, bool no_lock)
 {
 	const struct tcp_sock *tp = tcp_sk(sk); /* iff sk_type == SOCK_STREAM */
 	const struct inet_connection_sock *icsk = inet_csk(sk);
@@ -3316,7 +3316,8 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
 		return;
 	}
 
-	slow = lock_sock_fast(sk);
+	if (!no_lock)
+		slow = lock_sock_fast(sk);
 
 	info->tcpi_ca_state = icsk->icsk_ca_state;
 	info->tcpi_retransmits = icsk->icsk_retransmits;
@@ -3390,7 +3391,9 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info)
 	info->tcpi_bytes_retrans = tp->bytes_retrans;
 	info->tcpi_dsack_dups = tp->dsack_dups;
 	info->tcpi_reord_seen = tp->reord_seen;
-	unlock_sock_fast(sk, slow);
+
+	if (!no_lock)
+		unlock_sock_fast(sk, slow);
 }
 EXPORT_SYMBOL_GPL(tcp_get_info);
 
@@ -3535,7 +3538,7 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
 		if (get_user(len, optlen))
 			return -EFAULT;
 
-		tcp_get_info(sk, &info);
+		tcp_get_info(sk, &info, false);
 
 		len = min_t(unsigned int, len, sizeof(info));
 		if (put_user(len, optlen))

diff --git a/net/ipv4/tcp_diag.c b/net/ipv4/tcp_diag.c
@@ -34,7 +34,7 @@ static void tcp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
 		r->idiag_wqueue = tp->write_seq - tp->snd_una;
 	}
 	if (info)
-		tcp_get_info(sk, info);
+		tcp_get_info(sk, info, false);
 }
 
 #ifdef CONFIG_TCP_MD5SIG

diff --git a/net/mptcp/mptcp_ctrl.c b/net/mptcp/mptcp_ctrl.c
@@ -1530,7 +1530,7 @@ void mptcp_del_sock(struct sock *sk)
 						    GFP_ATOMIC);
 
 			if (mpcb->master_info)
-				tcp_get_info(sk, mpcb->master_info);
+				tcp_get_info(sk, mpcb->master_info, true);
 		}
 
 		mpcb->master_sk = NULL;
@@ -2718,7 +2718,7 @@ int mptcp_get_info(const struct sock *meta_sk, char __user *optval, int optlen)
 		if (mpcb->master_sk) {
 			struct tcp_info info;
 
-			tcp_get_info(mpcb->master_sk, &info);
+			tcp_get_info(mpcb->master_sk, &info, true);
 			if (copy_to_user((void __user *)m_info.initial, &info, info_len))
 				return -EFAULT;
 		} else if (meta_tp->record_master_info && mpcb->master_info) {
@@ -2741,7 +2741,7 @@ int mptcp_get_info(const struct sock *meta_sk, char __user *optval, int optlen)
 			struct tcp_info t_info;
 			unsigned int tmp_len;
 
-			tcp_get_info(mptcp_to_sock(mptcp), &t_info);
+			tcp_get_info(mptcp_to_sock(mptcp), &t_info, true);
 
 			tmp_len = min_t(unsigned int, len, info_len);
 			len -= tmp_len;