MFC r368058:

Ensure consistent error messages from ifconfig(8).

If multiple threads are invoking "ifconfig XXX create" a race may occur
which can lead to two different error messages for the same error.

a) ifconfig: SIOCIFCREATE2: File exists
b) ifconfig: interface XXX already exists

This patch ensures ifconfig prints the same error code
for the same case.

Reviewed by:	imp@ and kib@
Differential Revision:	https://reviews.freebsd.org/D27380
Sponsored by:	Mellanox Technologies // NVIDIA Networking

6 files changed, 18 insertions, 8 deletions

diff --git a/sbin/ifconfig/ifclone.c b/sbin/ifconfig/ifclone.c
index 21dcdc3dec8e8..30ce5b2461252 100644
--- a/sbin/ifconfig/ifclone.c
+++ b/sbin/ifconfig/ifclone.c
@@ -138,8 +138,7 @@ ifclonecreate(int s, void *arg)
 	}
 	if (clone_cb == NULL) {
 		/* NB: no parameters */
-		if (ioctl(s, SIOCIFCREATE2, &ifr) < 0)
-			err(1, "SIOCIFCREATE2");
+	  	ioctl_ifcreate(s, &ifr);
 	} else {
 		clone_cb(s, &ifr);
 	}
diff --git a/sbin/ifconfig/ifconfig.c b/sbin/ifconfig/ifconfig.c
index 02c8339b1edb8..17d4cf6bf1717 100644
--- a/sbin/ifconfig/ifconfig.c
+++ b/sbin/ifconfig/ifconfig.c
@@ -185,6 +185,19 @@ usage(void)
 	exit(1);
 }
 
+void
+ioctl_ifcreate(int s, struct ifreq *ifr)
+{
+	if (ioctl(s, SIOCIFCREATE2, ifr) < 0) {
+		switch (errno) {
+		case EEXIST:
+			errx(1, "interface %s already exists", ifr->ifr_name);
+		default:
+			err(1, "SIOCIFCREATE2");
+		}
+	}
+}
+
 #define ORDERS_SIZE(x) sizeof(x) / sizeof(x[0])
 
 static int
diff --git a/sbin/ifconfig/ifconfig.h b/sbin/ifconfig/ifconfig.h
index 5a9af3aaa7b8b..bb4d0b77cb553 100644
--- a/sbin/ifconfig/ifconfig.h
+++ b/sbin/ifconfig/ifconfig.h
@@ -157,3 +157,4 @@ struct ifmediareq *ifmedia_getstate(int s);
 
 void print_vhid(const struct ifaddrs *, const char *);
 
+void ioctl_ifcreate(int s, struct ifreq *);
diff --git a/sbin/ifconfig/ifieee80211.c b/sbin/ifconfig/ifieee80211.c
index b13f674e6a830..bc0bf5fb77d00 100644
--- a/sbin/ifconfig/ifieee80211.c
+++ b/sbin/ifconfig/ifieee80211.c
@@ -5233,8 +5233,7 @@ wlan_create(int s, struct ifreq *ifr)
 	    memcmp(params.icp_bssid, zerobssid, sizeof(zerobssid)) == 0)
 		errx(1, "no bssid specified for WDS (use wlanbssid)");
 	ifr->ifr_data = (caddr_t) &params;
-	if (ioctl(s, SIOCIFCREATE2, ifr) < 0)
-		err(1, "SIOCIFCREATE2");
+	ioctl_ifcreate(s, ifr);
 
 	/* XXX preserve original name for ifclonecreate(). */
 	strlcpy(orig_name, name, sizeof(orig_name));
diff --git a/sbin/ifconfig/ifvlan.c b/sbin/ifconfig/ifvlan.c
index 3b37160c3c851..faa0c4e617088 100644
--- a/sbin/ifconfig/ifvlan.c
+++ b/sbin/ifconfig/ifvlan.c
@@ -105,8 +105,7 @@ vlan_create(int s, struct ifreq *ifr)
 			errx(1, "must specify a parent device for vlan create");
 		ifr->ifr_data = (caddr_t) &params;
 	}
-	if (ioctl(s, SIOCIFCREATE2, ifr) < 0)
-		err(1, "SIOCIFCREATE2");
+	ioctl_ifcreate(s, ifr);
 }
 
 static void
diff --git a/sbin/ifconfig/ifvxlan.c b/sbin/ifconfig/ifvxlan.c
index 7f78d2be88899..9c31358392203 100644
--- a/sbin/ifconfig/ifvxlan.c
+++ b/sbin/ifconfig/ifvxlan.c
@@ -191,8 +191,7 @@ vxlan_create(int s, struct ifreq *ifr)
 	vxlan_check_params();
 
 	ifr->ifr_data = (caddr_t) &params;
-	if (ioctl(s, SIOCIFCREATE2, ifr) < 0)
-		err(1, "SIOCIFCREATE2");
+	ioctl_ifcreate(s, ifr);
 }
 
 static