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Date:      Fri, 3 Jul 2015 12:09:06 +0000 (UTC)
From:      Roger Pau Monné <royger@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r285089 - head/sys/dev/xen/netfront
Message-ID:  <201507031209.t63C96wP074115@repo.freebsd.org>
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Author: royger
Date: Fri Jul  3 12:09:05 2015
New Revision: 285089
URL: https://svnweb.freebsd.org/changeset/base/285089

Log:
  netfront: preserve configuration across migrations
  
  Try to preserve the xn configuration when migrating. This is not always
  possible since the backend might not have the same set of options
  available, in which case we will try to preserve as many as possible.
  
  MFC after:    2 weeks
  PR:           183139
  Reported by:  mcdouga9@egr.msu.edu
  Sponsored by: Citrix Systems R&D

Modified:
  head/sys/dev/xen/netfront/netfront.c

Modified: head/sys/dev/xen/netfront/netfront.c
==============================================================================
--- head/sys/dev/xen/netfront/netfront.c	Fri Jul  3 11:16:20 2015	(r285088)
+++ head/sys/dev/xen/netfront/netfront.c	Fri Jul  3 12:09:05 2015	(r285089)
@@ -285,6 +285,8 @@ struct netfront_info {
 	multicall_entry_t	rx_mcl[NET_RX_RING_SIZE+1];
 	mmu_update_t		rx_mmu[NET_RX_RING_SIZE];
 	struct ifmedia		sc_media;
+
+	bool			xn_resume;
 };
 
 #define rx_mbufs xn_cdata.xn_rx_chain
@@ -500,6 +502,7 @@ netfront_resume(device_t dev)
 {
 	struct netfront_info *info = device_get_softc(dev);
 
+	info->xn_resume = true;
 	netif_disconnect_backend(info);
 	return (0);
 }
@@ -1982,18 +1985,33 @@ xn_query_features(struct netfront_info *
 static int
 xn_configure_features(struct netfront_info *np)
 {
-	int err;
+	int err, cap_enabled;
 
 	err = 0;
+
+	if (np->xn_resume &&
+	    ((np->xn_ifp->if_capenable & np->xn_ifp->if_capabilities)
+	    == np->xn_ifp->if_capenable)) {
+		/* Current options are available, no need to do anything. */
+		return (0);
+	}
+
+	/* Try to preserve as many options as possible. */
+	if (np->xn_resume)
+		cap_enabled = np->xn_ifp->if_capenable;
+	else
+		cap_enabled = UINT_MAX;
+
 #if __FreeBSD_version >= 700000 && (defined(INET) || defined(INET6))
-	if ((np->xn_ifp->if_capenable & IFCAP_LRO) != 0)
+	if ((np->xn_ifp->if_capenable & IFCAP_LRO) == (cap_enabled & IFCAP_LRO))
 		tcp_lro_free(&np->xn_lro);
 #endif
     	np->xn_ifp->if_capenable =
-	    np->xn_ifp->if_capabilities & ~(IFCAP_LRO|IFCAP_TSO4);
+	    np->xn_ifp->if_capabilities & ~(IFCAP_LRO|IFCAP_TSO4) & cap_enabled;
 	np->xn_ifp->if_hwassist &= ~CSUM_TSO;
 #if __FreeBSD_version >= 700000 && (defined(INET) || defined(INET6))
-	if (xn_enable_lro && (np->xn_ifp->if_capabilities & IFCAP_LRO) != 0) {
+	if (xn_enable_lro && (np->xn_ifp->if_capabilities & IFCAP_LRO) ==
+	    (cap_enabled & IFCAP_LRO)) {
 		err = tcp_lro_init(&np->xn_lro);
 		if (err) {
 			device_printf(np->xbdev, "LRO initialization failed\n");
@@ -2002,7 +2020,8 @@ xn_configure_features(struct netfront_in
 			np->xn_ifp->if_capenable |= IFCAP_LRO;
 		}
 	}
-	if ((np->xn_ifp->if_capabilities & IFCAP_TSO4) != 0) {
+	if ((np->xn_ifp->if_capabilities & IFCAP_TSO4) ==
+	    (cap_enabled & IFCAP_TSO4)) {
 		np->xn_ifp->if_capenable |= IFCAP_TSO4;
 		np->xn_ifp->if_hwassist |= CSUM_TSO;
 	}

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