diff -ur linux-2.4.21/include/linux/sunrpc/svcsock.h nfs/include/linux/sunrpc/svcsock.h
--- linux-2.4.21/include/linux/sunrpc/svcsock.h	2003-09-15 23:02:05.000000000 +0200
+++ nfs/include/linux/sunrpc/svcsock.h	2003-10-09 16:43:30.000000000 +0200
@@ -33,6 +33,7 @@
 #define	SK_CHNGBUF	7			/* need to change snd/rcv buffer sizes */
 
 	int			sk_reserved;	/* space on outq that is reserved */
+	struct semaphore	sk_sendlock;
 
 	int			(*sk_recvfrom)(struct svc_rqst *rqstp);
 	int			(*sk_sendto)(struct svc_rqst *rqstp);
diff -ur linux-2.4.21/net/sunrpc/svcsock.c nfs/net/sunrpc/svcsock.c
--- linux-2.4.21/net/sunrpc/svcsock.c	2003-10-08 15:36:27.000000000 +0200
+++ nfs/net/sunrpc/svcsock.c	2003-10-09 16:46:15.000000000 +0200
@@ -935,6 +935,7 @@
 static int
 svc_tcp_sendto(struct svc_rqst *rqstp)
 {
+	struct svc_sock	*svsk = rqstp->rq_sock;
 	struct svc_buf	*bufp = &rqstp->rq_resbuf;
 	int sent;
 
@@ -949,7 +950,10 @@
 	if (test_bit(SK_DEAD, &rqstp->rq_sock->sk_flags))
 		return -ENOTCONN;
 
+	down(&svsk->sk_sendlock);
 	sent = svc_sendto(rqstp, bufp->iov, bufp->nriov);
+	up(&svsk->sk_sendlock);
+
 	if (sent != bufp->len<<2) {
 		printk(KERN_NOTICE "rpc-srv/tcp: %s: sent only %d bytes of %d - shutting down socket\n",
 		       rqstp->rq_sock->sk_server->sv_name,
@@ -1191,6 +1195,8 @@
 	}
 	memset(svsk, 0, sizeof(*svsk));
 
+	init_MUTEX(&svsk->sk_sendlock);
+
 	inet = sock->sk;
 	inet->user_data = svsk;
 	svsk->sk_sock = sock;