From ef25cb39a9cb9e36a8872dcd252686023eaec959 Mon Sep 17 00:00:00 2001
From: Stefano Brivio <sbrivio@redhat.com>
Date: Thu, 18 Mar 2021 11:36:55 +0100
Subject: [PATCH] passt: Set soft limit for number of open files to hard limit

Default value for /proc/sys/fs/nr_open is 2^20, which is more than
enough: set this hard limit as current (soft) limit on start, and
drop the 'ulimit -n' from the demo script.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 doc/demo.sh |  1 -
 passt.c     | 12 ++++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/doc/demo.sh b/doc/demo.sh
index a5b45b5..fe24751 100755
--- a/doc/demo.sh
+++ b/doc/demo.sh
@@ -75,7 +75,6 @@ sysctl -w net.ipv6.conf.all.forwarding=1
 ethtool -K veth_passt tx off
 ip netns exec passt ethtool -K veth_passt tx off
 ip netns exec passt sysctl -w net.ipv4.ping_group_range="0 2147483647"
-ulimit -n 300000
 
 
 ip netns exec passt ./passt
diff --git a/passt.c b/passt.c
index 9786221..6b160c0 100644
--- a/passt.c
+++ b/passt.c
@@ -18,6 +18,7 @@
 #include <sys/socket.h>
 #include <sys/types.h>
 #include <sys/ioctl.h>
+#include <sys/resource.h>
 #include <sys/un.h>
 #include <ifaddrs.h>
 #include <linux/if_ether.h>
@@ -513,6 +514,7 @@ int main(int argc, char **argv)
 	struct timespec last_time;
 	struct ctx c = { 0 };
 	int nfds, i, fd_unix;
+	struct rlimit limit;
 
 	if (argc != 1)
 		usage(argv[0]);
@@ -528,6 +530,16 @@ int main(int argc, char **argv)
 		exit(EXIT_FAILURE);
 	}
 
+	if (getrlimit(RLIMIT_NOFILE, &limit)) {
+		perror("getrlimit");
+		exit(EXIT_FAILURE);
+	}
+	limit.rlim_cur = limit.rlim_max;
+	if (setrlimit(RLIMIT_NOFILE, &limit)) {
+		perror("setrlimit");
+		exit(EXIT_FAILURE);
+	}
+
 	if (icmp_sock_init(&c) || tcp_sock_init(&c) || udp_sock_init(&c))
 		exit(EXIT_FAILURE);