svn commit: r333454 - head/sys/dev/ena

[Marcin Wojtas]

Author: mw
Date: Thu May 10 09:32:59 2018
New Revision: 333454
URL: https://svnweb.freebsd.org/changeset/base/333454

Log:
  Skip setting the MTU for ENA if it is not changing
  
  On AWS, a network interface can get reinitialized every 30 minutes due
  to the MTU being (re)set when a new DHCP lease is obtained. This can
  cause packet drop, along with annoying syslog messages.
  
  Skip setting the MTU in the ena driver if the new MTU is the same as the
  old MTU. Note this fix is already in the netfront driver.
  
  Testing: Verified ena up/down messages do not appear every 30 min in
  /var/log/messages with the fix in place.
  
  Submitted by:   Krishna Yenduri <kyenduri at brkt.com>
  Reviewed by: Michal Krawczyk <mk at semihalf.com>

Modified:
  head/sys/dev/ena/ena.c

Modified: head/sys/dev/ena/ena.c
==============================================================================
--- head/sys/dev/ena/ena.c	Thu May 10 09:25:51 2018	(r333453)
+++ head/sys/dev/ena/ena.c	Thu May 10 09:32:59 2018	(r333454)
@@ -2368,6 +2368,8 @@ ena_ioctl(if_t ifp, u_long command, caddr_t data)
 	rc = 0;
 	switch (command) {
 	case SIOCSIFMTU:
+		if (ifp->if_mtu == ifr->ifr_mtu)
+			break;
 		sx_xlock(&adapter->ioctl_sx);
 		ena_down(adapter);