[Xen-devel] [PATCH] Make frontend features distinct from netback feature flags.

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

Make sure that if a feature flag is disabled by ethtool on netback
that we do not gratuitously re-enabled it when we check the frontend
features during ring connection.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 drivers/xen/netback/common.h    |   15 ++++++---
 drivers/xen/netback/interface.c |   68 ++++++++++++++++++++++++++++++--------
 drivers/xen/netback/netback.c   |    2 +-
 drivers/xen/netback/xenbus.c    |   51 +++++++++++------------------
 4 files changed, 83 insertions(+), 53 deletions(-)

diff --git a/drivers/xen/netback/common.h b/drivers/xen/netback/common.h
index 1cbc4ff..a673331 100644
--- a/drivers/xen/netback/common.h
+++ b/drivers/xen/netback/common.h
@@ -76,14 +76,18 @@ struct xen_netif {
        struct vm_struct *tx_comms_area;
        struct vm_struct *rx_comms_area;
 
-       /* Set of features that can be turned on in dev->features. */
-       int features;
+    /* Flags that must not be set in dev->features */
+    int features_disabled;
 
-       int smart_poll;
+       /* Frontend feature information. */
+    u8 can_sg:1;
+    u8 gso:1;
+    u8 gso_prefix:1;
+    u8 csum:1;
+    u8 smart_poll:1;
 
        /* Internal feature information. */
        u8 can_queue:1;     /* can queue packets for receiver? */
-       u8 gso_prefix:1;    /* use a prefix segment for GSO information */
 
        /* Allow netif_be_start_xmit() to peek ahead in the rx request
         * ring.  This is a prediction of what rx_req_cons will be once
@@ -189,6 +193,7 @@ void netif_accel_init(void);
 
 void netif_disconnect(struct xen_netif *netif);
 
+void netif_set_features(struct xen_netif *netif);
 struct xen_netif *netif_alloc(struct device *parent, domid_t domid, unsigned 
int handle);
 int netif_map(struct xen_netif *netif, unsigned long tx_ring_ref,
              unsigned long rx_ring_ref, unsigned int evtchn);
@@ -225,7 +230,7 @@ static inline int netbk_can_queue(struct net_device *dev)
 static inline int netbk_can_sg(struct net_device *dev)
 {
        struct xen_netif *netif = netdev_priv(dev);
-       return netif->features & NETIF_F_SG;
+       return netif->can_sg;
 }
 
 struct pending_tx_info {
diff --git a/drivers/xen/netback/interface.c b/drivers/xen/netback/interface.c
index 172ef4c..2e8508a 100644
--- a/drivers/xen/netback/interface.c
+++ b/drivers/xen/netback/interface.c
@@ -121,31 +121,69 @@ static int netbk_change_mtu(struct net_device *dev, int 
mtu)
        return 0;
 }
 
-static int netbk_set_sg(struct net_device *dev, u32 data)
+void netif_set_features(struct xen_netif *netif)
 {
-       if (data) {
-               struct xen_netif *netif = netdev_priv(dev);
+       struct net_device *dev = netif->dev;
+       int features = dev->features;
+
+       if (netif->can_sg)
+               features |= NETIF_F_SG;
+       if (netif->gso || netif->gso_prefix)
+               features |= NETIF_F_TSO;
+       if (netif->csum)
+               features |= NETIF_F_IP_CSUM;
+
+       features &= ~(netif->features_disabled);
 
-               if (!(netif->features & NETIF_F_SG))
+       if (!(features & NETIF_F_SG) && dev->mtu > ETH_DATA_LEN)
+               dev->mtu = ETH_DATA_LEN;
+
+       dev->features = features;
+}
+
+static int netbk_set_tx_csum(struct net_device *dev, u32 data)
+{
+       struct xen_netif *netif = netdev_priv(dev);
+       if (data) {
+               if (!netif->csum)
                        return -ENOSYS;
+               netif->features_disabled &= ~NETIF_F_IP_CSUM;
+       } else {
+               netif->features_disabled |= NETIF_F_IP_CSUM;
        }
 
-       if (dev->mtu > ETH_DATA_LEN)
-               dev->mtu = ETH_DATA_LEN;
+       netif_set_features(netif);
+       return 0;
+}
 
-       return ethtool_op_set_sg(dev, data);
+static int netbk_set_sg(struct net_device *dev, u32 data)
+{
+       struct xen_netif *netif = netdev_priv(dev);
+       if (data) {
+               if (!netif->can_sg)
+                       return -ENOSYS;
+               netif->features_disabled &= ~NETIF_F_SG;
+       } else {
+               netif->features_disabled |= NETIF_F_SG;
+       }
+
+       netif_set_features(netif);
+       return 0;
 }
 
 static int netbk_set_tso(struct net_device *dev, u32 data)
 {
+       struct xen_netif *netif = netdev_priv(dev);
        if (data) {
-               struct xen_netif *netif = netdev_priv(dev);
-
-               if (!(netif->features & NETIF_F_TSO))
+               if (!netif->gso && !netif->gso_prefix)
                        return -ENOSYS;
+               netif->features_disabled &= ~NETIF_F_TSO;
+       } else {
+               netif->features_disabled |= NETIF_F_TSO;
        }
 
-       return ethtool_op_set_tso(dev, data);
+       netif_set_features(netif);
+       return 0;
 }
 
 static void netbk_get_drvinfo(struct net_device *dev,
@@ -200,7 +238,7 @@ static struct ethtool_ops network_ethtool_ops =
        .get_drvinfo = netbk_get_drvinfo,
 
        .get_tx_csum = ethtool_op_get_tx_csum,
-       .set_tx_csum = ethtool_op_set_tx_csum,
+       .set_tx_csum = netbk_set_tx_csum,
        .get_sg = ethtool_op_get_sg,
        .set_sg = netbk_set_sg,
        .get_tso = ethtool_op_get_tso,
@@ -242,7 +280,8 @@ struct xen_netif *netif_alloc(struct device *parent, 
domid_t domid, unsigned int
        netif->domid  = domid;
        netif->group  = -1;
        netif->handle = handle;
-       netif->features = NETIF_F_SG;
+       netif->can_sg = 1;
+       netif->csum = 1;
        atomic_set(&netif->refcnt, 1);
        init_waitqueue_head(&netif->waiting_to_free);
        netif->dev = dev;
@@ -259,8 +298,7 @@ struct xen_netif *netif_alloc(struct device *parent, 
domid_t domid, unsigned int
        init_timer(&netif->tx_queue_timeout);
 
        dev->netdev_ops = &netback_ops;
-       dev->features   = NETIF_F_IP_CSUM|NETIF_F_SG;
-
+       netif_set_features(netif);
        SET_ETHTOOL_OPS(dev, &network_ethtool_ops);
 
        dev->tx_queue_len = netbk_queue_length;
diff --git a/drivers/xen/netback/netback.c b/drivers/xen/netback/netback.c
index 93f0686..426aada 100644
--- a/drivers/xen/netback/netback.c
+++ b/drivers/xen/netback/netback.c
@@ -238,7 +238,7 @@ static struct sk_buff *netbk_copy_skb(struct sk_buff *skb)
 
 static inline int netbk_max_required_rx_slots(struct xen_netif *netif)
 {
-       if (netif->features & (NETIF_F_SG|NETIF_F_TSO))
+       if (netif->can_sg || netif->gso || netif->gso_prefix)
                return MAX_SKB_FRAGS + 2; /* header + extra_info + frags */
        return 1; /* all in one */
 }
diff --git a/drivers/xen/netback/xenbus.c b/drivers/xen/netback/xenbus.c
index 74c035b..81b3a96 100644
--- a/drivers/xen/netback/xenbus.c
+++ b/drivers/xen/netback/xenbus.c
@@ -412,6 +412,7 @@ static void connect(struct backend_info *be)
 
 static int connect_rings(struct backend_info *be)
 {
+       struct xen_netif *netif = be->netif;
        struct xenbus_device *dev = be->dev;
        unsigned long tx_ring_ref, rx_ring_ref;
        unsigned int evtchn, rx_copy;
@@ -445,61 +446,47 @@ static int connect_rings(struct backend_info *be)
        if (!rx_copy)
                return -EOPNOTSUPP;
 
-       if (be->netif->dev->tx_queue_len != 0) {
+       if (netif->dev->tx_queue_len != 0) {
                if (xenbus_scanf(XBT_NIL, dev->otherend,
                                 "feature-rx-notify", "%d", &val) < 0)
                        val = 0;
                if (val)
-                       be->netif->can_queue = 1;
+                       netif->can_queue = 1;
                else
                        /* Must be non-zero for pfifo_fast to work. */
-                       be->netif->dev->tx_queue_len = 1;
+                       netif->dev->tx_queue_len = 1;
        }
 
-       if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg", "%d", &val) < 0)
+       if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg",
+                        "%d", &val) < 0)
                val = 0;
-       if (!val) {
-               be->netif->features &= ~NETIF_F_SG;
-               be->netif->dev->features &= ~NETIF_F_SG;
-               if (be->netif->dev->mtu > ETH_DATA_LEN)
-                       be->netif->dev->mtu = ETH_DATA_LEN;
-       }
+       netif->can_sg = !!val;
 
        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
-                       "%d", &val) < 0)
+                        "%d", &val) < 0)
                val = 0;
-       if (val) {
-               be->netif->features |= NETIF_F_TSO;
-               be->netif->dev->features |= NETIF_F_TSO;
-       }
+       netif->gso = !!val;
 
        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4-prefix",
-                       "%d", &val) < 0)
+                        "%d", &val) < 0)
                val = 0;
-       if (val) {
-               be->netif->features |= NETIF_F_TSO;
-               be->netif->dev->features |= NETIF_F_TSO;
-               be->netif->gso_prefix = 1;
-       }
+       netif->gso_prefix = !!val;
 
        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
-                       "%d", &val) < 0)
+                        "%d", &val) < 0)
                val = 0;
-       if (val) {
-               be->netif->features &= ~NETIF_F_IP_CSUM;
-               be->netif->dev->features &= ~NETIF_F_IP_CSUM;
-       }
+       netif->csum = !!val;
 
        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-smart-poll",
-                       "%d", &val) < 0)
+                        "%d", &val) < 0)
                val = 0;
-       if (val)
-               be->netif->smart_poll = 1;
-       else
-               be->netif->smart_poll = 0;
+       netif->smart_poll = !!val;
+
+       /* Set dev->features */
+       netif_set_features(netif);
 
        /* Map the shared frame, irq etc. */
-       err = netif_map(be->netif, tx_ring_ref, rx_ring_ref, evtchn);
+       err = netif_map(netif, tx_ring_ref, rx_ring_ref, evtchn);
        if (err) {
                xenbus_dev_fatal(dev, err,
                                 "mapping shared-frames %lu/%lu port %u",
-- 
1.5.6.5


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