dev: support deferring device flag change notifications

Split dev_change_flags() into two functions: __dev_change_flags() to
perform the actual changes and __dev_notify_flags() to invoke netdevice
notifiers. This will be used by rtnl_link to defer netlink notifications
until the device has been fully configured.

This changes ordering of some operations, in particular:

- netlink notifications are sent after all changes have been performed.
  As a side effect this surpresses one unnecessary netlink message when
  the IFF_UP and other flags are changed simultaneously.

- The NETDEV_UP/NETDEV_DOWN and NETDEV_CHANGE notifiers are invoked
  after all changes have been performed. Their relative is unchanged.

- net_dmaengine_put() is invoked before the NETDEV_DOWN notifier instead
  of afterwards. This should not make any difference since both RX and TX
  are already shut down at this point.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 1bfda90..c79a88b 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1587,7 +1587,9 @@ extern int                dev_valid_name(const char *name);
 extern int             dev_ioctl(struct net *net, unsigned int cmd, void __user *);
 extern int             dev_ethtool(struct net *net, struct ifreq *);
 extern unsigned                dev_get_flags(const struct net_device *);
+extern int             __dev_change_flags(struct net_device *, unsigned int flags);
 extern int             dev_change_flags(struct net_device *, unsigned);
+extern void            __dev_notify_flags(struct net_device *, unsigned int old_flags);
 extern int             dev_change_name(struct net_device *, const char *);
 extern int             dev_set_alias(struct net_device *, const char *, size_t);
 extern int             dev_change_net_namespace(struct net_device *,

diff --git a/net/core/dev.c b/net/core/dev.c
index 75332b0..e5972f7 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1113,19 +1113,7 @@ void dev_load(struct net *net, const char *name)
 }
 EXPORT_SYMBOL(dev_load);
 
-/**
- *     dev_open        - prepare an interface for use.
- *     @dev:   device to open
- *
- *     Takes a device from down to up state. The device's private open
- *     function is invoked and then the multicast lists are loaded. Finally
- *     the device is moved into the up state and a %NETDEV_UP message is
- *     sent to the netdev notifier chain.
- *
- *     Calling this function on an active interface is a nop. On a failure
- *     a negative errno code is returned.
- */
-int dev_open(struct net_device *dev)
+static int __dev_open(struct net_device *dev)
 {
        const struct net_device_ops *ops = dev->netdev_ops;
        int ret;
@@ -1133,13 +1121,6 @@ int dev_open(struct net_device *dev)
        ASSERT_RTNL();
 
        /*
-        *      Is it already up?
-        */
-
-       if (dev->flags & IFF_UP)
-               return 0;
-
-       /*
         *      Is it even present?
         */
        if (!netif_device_present(dev))
@@ -1187,36 +1168,57 @@ int dev_open(struct net_device *dev)
                 *      Wakeup transmit queue engine
                 */
                dev_activate(dev);
-
-               /*
-                *      ... and announce new interface.
-                */
-               call_netdevice_notifiers(NETDEV_UP, dev);
        }
 
        return ret;
 }
-EXPORT_SYMBOL(dev_open);
 
 /**
- *     dev_close - shutdown an interface.
- *     @dev: device to shutdown
+ *     dev_open        - prepare an interface for use.
+ *     @dev:   device to open
  *
- *     This function moves an active device into down state. A
- *     %NETDEV_GOING_DOWN is sent to the netdev notifier chain. The device
- *     is then deactivated and finally a %NETDEV_DOWN is sent to the notifier
- *     chain.
+ *     Takes a device from down to up state. The device's private open
+ *     function is invoked and then the multicast lists are loaded. Finally
+ *     the device is moved into the up state and a %NETDEV_UP message is
+ *     sent to the netdev notifier chain.
+ *
+ *     Calling this function on an active interface is a nop. On a failure
+ *     a negative errno code is returned.
  */
-int dev_close(struct net_device *dev)
+int dev_open(struct net_device *dev)
+{
+       int ret;
+
+       /*
+        *      Is it already up?
+        */
+       if (dev->flags & IFF_UP)
+               return 0;
+
+       /*
+        *      Open device
+        */
+       ret = __dev_open(dev);
+       if (ret < 0)
+               return ret;
+
+       /*
+        *      ... and announce new interface.
+        */
+       rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
+       call_netdevice_notifiers(NETDEV_UP, dev);
+
+       return ret;
+}
+EXPORT_SYMBOL(dev_open);
+
+static int __dev_close(struct net_device *dev)
 {
        const struct net_device_ops *ops = dev->netdev_ops;
-       ASSERT_RTNL();
 
+       ASSERT_RTNL();
        might_sleep();
 
-       if (!(dev->flags & IFF_UP))
-               return 0;
-
        /*
         *      Tell people we are going down, so that they can
         *      prepare to death, when device is still operating.
@@ -1252,14 +1254,34 @@ int dev_close(struct net_device *dev)
        dev->flags &= ~IFF_UP;
 
        /*
-        * Tell people we are down
+        *      Shutdown NET_DMA
         */
-       call_netdevice_notifiers(NETDEV_DOWN, dev);
+       net_dmaengine_put();
+
+       return 0;
+}
+
+/**
+ *     dev_close - shutdown an interface.
+ *     @dev: device to shutdown
+ *
+ *     This function moves an active device into down state. A
+ *     %NETDEV_GOING_DOWN is sent to the netdev notifier chain. The device
+ *     is then deactivated and finally a %NETDEV_DOWN is sent to the notifier
+ *     chain.
+ */
+int dev_close(struct net_device *dev)
+{
+       if (!(dev->flags & IFF_UP))
+               return 0;
+
+       __dev_close(dev);
 
        /*
-        *      Shutdown NET_DMA
+        * Tell people we are down
         */
-       net_dmaengine_put();
+       rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
+       call_netdevice_notifiers(NETDEV_DOWN, dev);
 
        return 0;
 }
@@ -4299,18 +4321,10 @@ unsigned dev_get_flags(const struct net_device *dev)
 }
 EXPORT_SYMBOL(dev_get_flags);
 
-/**
- *     dev_change_flags - change device settings
- *     @dev: device
- *     @flags: device state flags
- *
- *     Change settings on device based state flags. The flags are
- *     in the userspace exported format.
- */
-int dev_change_flags(struct net_device *dev, unsigned flags)
+int __dev_change_flags(struct net_device *dev, unsigned int flags)
 {
-       int ret, changes;
        int old_flags = dev->flags;
+       int ret;
 
        ASSERT_RTNL();
 
@@ -4341,17 +4355,12 @@ int dev_change_flags(struct net_device *dev, unsigned flags)
 
        ret = 0;
        if ((old_flags ^ flags) & IFF_UP) {     /* Bit is different  ? */
-               ret = ((old_flags & IFF_UP) ? dev_close : dev_open)(dev);
+               ret = ((old_flags & IFF_UP) ? __dev_close : __dev_open)(dev);
 
                if (!ret)
                        dev_set_rx_mode(dev);
        }
 
-       if (dev->flags & IFF_UP &&
-           ((old_flags ^ dev->flags) & ~(IFF_UP | IFF_PROMISC | IFF_ALLMULTI |
-                                         IFF_VOLATILE)))
-               call_netdevice_notifiers(NETDEV_CHANGE, dev);
-
        if ((flags ^ dev->gflags) & IFF_PROMISC) {
                int inc = (flags & IFF_PROMISC) ? 1 : -1;
 
@@ -4370,11 +4379,47 @@ int dev_change_flags(struct net_device *dev, unsigned flags)
                dev_set_allmulti(dev, inc);
        }
 
-       /* Exclude state transition flags, already notified */
-       changes = (old_flags ^ dev->flags) & ~(IFF_UP | IFF_RUNNING);
+       return ret;
+}
+
+void __dev_notify_flags(struct net_device *dev, unsigned int old_flags)
+{
+       unsigned int changes = dev->flags ^ old_flags;
+
+       if (changes & IFF_UP) {
+               if (dev->flags & IFF_UP)
+                       call_netdevice_notifiers(NETDEV_UP, dev);
+               else
+                       call_netdevice_notifiers(NETDEV_DOWN, dev);
+       }
+
+       if (dev->flags & IFF_UP &&
+           (changes & ~(IFF_UP | IFF_PROMISC | IFF_ALLMULTI | IFF_VOLATILE)))
+               call_netdevice_notifiers(NETDEV_CHANGE, dev);
+}
+
+/**
+ *     dev_change_flags - change device settings
+ *     @dev: device
+ *     @flags: device state flags
+ *
+ *     Change settings on device based state flags. The flags are
+ *     in the userspace exported format.
+ */
+int dev_change_flags(struct net_device *dev, unsigned flags)
+{
+       int ret, changes;
+       int old_flags = dev->flags;
+
+       ret = __dev_change_flags(dev, flags);
+       if (ret < 0)
+               return ret;
+
+       changes = old_flags ^ dev->flags;
        if (changes)
                rtmsg_ifinfo(RTM_NEWLINK, dev, changes);
 
+       __dev_notify_flags(dev, old_flags);
        return ret;
 }
 EXPORT_SYMBOL(dev_change_flags);

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 020e43b..c21ec42 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1427,8 +1427,6 @@ static int rtnetlink_event(struct notifier_block *this, unsigned long event, voi
        switch (event) {
        case NETDEV_UP:
        case NETDEV_DOWN:
-               rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
-               break;
        case NETDEV_PRE_UP:
        case NETDEV_POST_INIT:
        case NETDEV_REGISTER: