From 31ecd29b3b3f51145fd78f63087c10e9fcadf999 Mon Sep 17 00:00:00 2001
From: Steve Dickson <steved@redhat.com>
Date: Tue, 22 May 2018 12:41:59 +0200
Subject: [PATCH] Listen on a TCP socket
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rpc.rquotad spins in libtirpc's rendezvous_request() on accepting TCP
connections because the polled TCP socket is not listening:

poll([{fd=4, events=POLLIN|POLLPRI|POLLRDNORM|POLLRDBAND}, {fd=5,
  events=POLLIN|POLLPRI|POLLRDNORM|POLLRDBAND}, {fd=6,
  events=POLLIN|POLLPRI|POLLRDNORM|POLLRDBAND}, {fd=7,
  events=POLLIN|POLLPRI|POLLRDNORM|POLLRDBAND}], 4, -1) = 2 ([{fd=5,
  revents=POLLHUP}, {fd=7, revents=POLLHUP}])
accept(5, 0x7ffe61698700, [128])        = -1 EINVAL (Invalid argument)
accept(7, 0x7ffe61698700, [128])        = -1 EINVAL (Invalid argument)

The polled descriptors are:

rpc.rquot 21981 root    4u  IPv4 80449159      0t0      UDP *:rquotad
rpc.rquot 21981 root    5u  sock      0,9      0t0 80449162 protocol: TCP
rpc.rquot 21981 root    6u  IPv6 80449165      0t0      UDP *:rquotad
rpc.rquot 21981 root    7u  sock      0,9      0t0 80449168 protocol: TCPv6

That results into a high CPU usage just after staring rpc.rquotad
process.

This patch adds a listen() call to svc_create_sock()
routine which is needed with libtirpc version of svc_tli_create()
as well as a needed IPv6 setsockopt().

Signed-off-by: Petr Písař <ppisar@redhat.com>
---
 svc_socket.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/svc_socket.c b/svc_socket.c
index 8a44604..d2e3abf 100644
--- a/svc_socket.c
+++ b/svc_socket.c
@@ -118,6 +118,15 @@ static int svc_create_sock(struct addrinfo *ai)
 		return -1;
 	}
 
+	if (ai->ai_family == AF_INET6) {
+		if (setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY,
+				&optval, sizeof(optval)) < 0) {
+			errstr(_("Cannot set IPv6 socket options: %s\n"), strerror(errno));
+			close(fd);
+			return -1;
+		}
+	}
+
 	if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)) < 0) {
 		errstr(_("Cannot set socket options: %s\n"), strerror(errno));
 		close(fd);
@@ -129,6 +138,15 @@ static int svc_create_sock(struct addrinfo *ai)
 		close(fd);
 		return -1;
 	}
+
+	if (ai->ai_protocol == IPPROTO_TCP) {
+		if (listen(fd, SOMAXCONN) < 0) {
+			errstr(_("Cannot listen to address: %s\n"), strerror(errno));
+			close(fd);
+			return -1;
+		}
+	}
+
 	return fd;
 }
 
-- 
2.14.3