diff -urN 2.3.18ac7/include/net/sock.h 2.3.18ac7-netlockup/include/net/sock.h
--- 2.3.18ac7/include/net/sock.h	Mon Sep 20 22:44:38 1999
+++ 2.3.18ac7-netlockup/include/net/sock.h	Tue Sep 21 19:54:58 1999
@@ -312,6 +312,16 @@
 	__u32	last_seg_size;	/* Size of last incoming segment */
 	__u32	rcv_mss;	/* MSS used for delayed ACK decisions */ 
 
+	/* The syn_wait_lock is necessary only to avoid tcp_get_info having
+	   to grab the main lock sock while browsing the listening hash
+	   (otherwise it's deadlock prone).
+	   This lock is acquired in read mode only from tcp_get_info() and
+	   it's acquired in write mode _only_ from code that is actively
+	   changing the syn_wait_queue. All readers that are holding
+	   the master sock lock don't need to grab this lock in read mode
+	   too as the syn_wait_queue writes are always protected from
+	   the main sock lock. */
+	rwlock_t		syn_wait_lock;
 	struct open_request	*syn_wait_queue;
 	struct open_request	**syn_wait_last;
 
diff -urN 2.3.18ac7/include/net/tcp.h 2.3.18ac7-netlockup/include/net/tcp.h
--- 2.3.18ac7/include/net/tcp.h	Mon Sep 20 22:44:38 1999
+++ 2.3.18ac7-netlockup/include/net/tcp.h	Tue Sep 21 19:54:58 1999
@@ -1129,23 +1129,57 @@
 
 extern __inline__ void tcp_synq_unlink(struct tcp_opt *tp, struct open_request *req, struct open_request *prev)
 {
+	write_lock(&tp->syn_wait_lock);
 	if(!req->dl_next)
 		tp->syn_wait_last = (struct open_request **)prev;
 	prev->dl_next = req->dl_next;
+	write_unlock(&tp->syn_wait_lock);
 }
 
 extern __inline__ void tcp_synq_queue(struct tcp_opt *tp, struct open_request *req)
 { 
+	write_lock(&tp->syn_wait_lock);
 	req->dl_next = NULL;
 	*tp->syn_wait_last = req; 
 	tp->syn_wait_last = &req->dl_next;
+	write_unlock(&tp->syn_wait_lock);
 }
 
 extern __inline__ void tcp_synq_init(struct tcp_opt *tp)
 {
+	write_lock(&tp->syn_wait_lock);
 	tp->syn_wait_queue = NULL;
 	tp->syn_wait_last = &tp->syn_wait_queue;
+	write_unlock(&tp->syn_wait_lock);
 }
+
+extern __inline__ void __tcp_synq_init(struct tcp_opt *tp)
+{
+	tp->syn_wait_lock = RW_LOCK_UNLOCKED;
+	tp->syn_wait_queue = NULL;
+	tp->syn_wait_last = &tp->syn_wait_queue;
+}
+
+#define tcp_synq_unlink_bh(tp, req, prev)		\
+	do {						\
+		local_bh_disable();			\
+		tcp_synq_unlink((tp), (req), (prev));	\
+		local_bh_enable();			\
+	} while (0)
+
+#define tcp_synq_queue_bh(tp, req)		\
+	do {					\
+		local_bh_disable();		\
+		tcp_synq_queue((tp), (req));	\
+		local_bh_enable();		\
+	} while (0)
+
+#define tcp_synq_init_bh(tp)			\
+	do {					\
+		local_bh_disable();		\
+		tcp_synq_init(tp);		\
+		local_bh_enable();		\
+	} while (0)
 
 extern void __tcp_inc_slow_timer(struct tcp_sl_timer *slt);
 extern __inline__ void tcp_inc_slow_timer(int timer)
diff -urN 2.3.18ac7/net/ipv4/tcp.c 2.3.18ac7-netlockup/net/ipv4/tcp.c
--- 2.3.18ac7/net/ipv4/tcp.c	Tue Sep 21 16:46:51 1999
+++ 2.3.18ac7-netlockup/net/ipv4/tcp.c	Tue Sep 21 19:59:04 1999
@@ -1471,6 +1471,9 @@
 	struct tcp_opt *tp = &(sk->tp_pinfo.af_tcp);
 	struct open_request *req = tp->syn_wait_queue;
 
+	/* make all the syn_wait_queue list local to us */
+	tcp_synq_init_bh(tp);
+
 	while(req) {
 		struct open_request *iter;
 		
@@ -1491,7 +1494,6 @@
 	}
 	BUG_TRAP(tp->syn_backlog == 0);
 	BUG_TRAP(sk->ack_backlog == 0);
-	tcp_synq_init(tp);
 }
 
 static __inline__ void tcp_kill_sk_queues(struct sock *sk)
@@ -1785,7 +1787,7 @@
 			goto out;
 	}
 
-	tcp_synq_unlink(tp, req, prev);
+	tcp_synq_unlink_bh(tp, req, prev);
 	newsk = req->sk;
 	req->class->destructor(req);
 	tcp_openreq_free(req);
diff -urN 2.3.18ac7/net/ipv4/tcp_input.c 2.3.18ac7-netlockup/net/ipv4/tcp_input.c
--- 2.3.18ac7/net/ipv4/tcp_input.c	Tue Sep 21 16:46:52 1999
+++ 2.3.18ac7-netlockup/net/ipv4/tcp_input.c	Tue Sep 21 19:54:59 1999
@@ -2406,7 +2406,7 @@
 		newtp->syn_seq = req->rcv_isn;
 		newtp->fin_seq = req->rcv_isn;
 		newtp->urg_data = 0;
-		tcp_synq_init(newtp);
+		__tcp_synq_init(newtp);
 		newtp->syn_backlog = 0;
 		if (skb->len >= 536)
 			newtp->last_seg_size = skb->len; 
diff -urN 2.3.18ac7/net/ipv4/tcp_ipv4.c 2.3.18ac7-netlockup/net/ipv4/tcp_ipv4.c
--- 2.3.18ac7/net/ipv4/tcp_ipv4.c	Tue Sep 14 14:35:58 1999
+++ 2.3.18ac7-netlockup/net/ipv4/tcp_ipv4.c	Tue Sep 21 19:54:59 1999
@@ -1964,7 +1964,7 @@
 	sk->write_space = tcp_write_space; 
 
 	/* Init SYN queue. */
-	tcp_synq_init(tp);
+	__tcp_synq_init(tp);
 
 	sk->tp_pinfo.af_tcp.af_specific = &ipv4_specific;
 
@@ -2114,7 +2114,7 @@
 			}
 
 skip_listen:
-			lock_sock(sk);
+			read_lock_bh(&tp->syn_wait_lock);
 			for (req = tp->syn_wait_queue; req; req = req->dl_next, num++) {
 				if (req->sk)
 					continue;
@@ -2127,12 +2127,12 @@
 				get_openreq(sk, req, tmpbuf, num);
 				len += sprintf(buffer+len, "%-127s\n", tmpbuf);
 				if(len >= length) {
+					read_unlock_bh(&tp->syn_wait_lock);
 					tcp_listen_unlock();
-					release_sock(sk);
 					goto out_no_bh;
 				}
 			}
-			release_sock(sk);
+			read_unlock_bh(&tp->syn_wait_lock);
 		}
 	}
 	tcp_listen_unlock();
diff -urN 2.3.18ac7/net/ipv6/tcp_ipv6.c 2.3.18ac7-netlockup/net/ipv6/tcp_ipv6.c
--- 2.3.18ac7/net/ipv6/tcp_ipv6.c	Tue Sep 14 14:35:29 1999
+++ 2.3.18ac7-netlockup/net/ipv6/tcp_ipv6.c	Tue Sep 21 19:54:59 1999
@@ -1843,7 +1843,7 @@
 	sk->max_ack_backlog = SOMAXCONN;
 
 	/* Init SYN queue. */
-	tcp_synq_init(tp);
+	__tcp_synq_init(tp);
 
 	sk->tp_pinfo.af_tcp.af_specific = &ipv6_specific;
 
@@ -2027,7 +2027,7 @@
 				}
 			}
 
-			lock_sock(sk);
+			read_lock_bh(&tp->syn_wait_lock);
 			for (req = tp->syn_wait_queue; req; req = req->dl_next, num++) {
 				if (req->sk)
 					continue;
@@ -2039,12 +2039,12 @@
 				get_openreq6(sk, req, tmpbuf, num);
 				len += sprintf(buffer+len, LINE_FMT, tmpbuf);
 				if(len >= length) { 
-					release_sock(sk);
+					read_unlock_bh(&tp->syn_wait_lock);
 					tcp_listen_unlock();
 					goto out_no_bh;
 				}
 			}
-			release_sock(sk);
+			read_unlock_bh(&tp->syn_wait_lock);
 		}
 	}
 	tcp_listen_unlock();