svn commit: r320219 - stable/11/sys/dev/xen/netfront

[Colin Percival]

Author: cperciva
Date: Thu Jun 22 05:30:27 2017
New Revision: 320219
URL: https://svnweb.freebsd.org/changeset/base/320219

Log:
  MFC r319491:
  
  Skip setting the MTU in the netfront driver (xn# devices) if the new MTU
  is the same as the old MTU.  In particular, on Amazon EC2 "T2" instances
  without this change, the network interface is reinitialized every 30
  minutes due to the MTU being (re)set when a new DHCP lease is obtained.
  
  Approved by:	re (delphij)

Modified:
  stable/11/sys/dev/xen/netfront/netfront.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/dev/xen/netfront/netfront.c
==============================================================================
--- stable/11/sys/dev/xen/netfront/netfront.c	Thu Jun 22 05:26:08 2017	(r320218)
+++ stable/11/sys/dev/xen/netfront/netfront.c	Thu Jun 22 05:30:27 2017	(r320219)
@@ -1767,6 +1767,9 @@ xn_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
 #endif
 		break;
 	case SIOCSIFMTU:
+		if (ifp->if_mtu == ifr->ifr_mtu)
+			break;
+
 		ifp->if_mtu = ifr->ifr_mtu;
 		ifp->if_drv_flags &= ~IFF_DRV_RUNNING;
 		xn_ifinit(sc);