[Xen-devel] [3/9] [NET] back: Replace netif->status with netif_carrier_ok

[Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>]

Hi:

[NET] back: Replace netif->status with netif_carrier_ok

The connection status to the frontend can be represented using
netif_carrier_ok instead of netif->status.  As a result, we delay
the construction of the dev qdisc until the carrier comes on.  This
is a prerequisite for adding a tx queue.

By the same token, netif->active is now simply the conjunction of
netif_running and netif_carrier_ok so it too can be removed.

Because netif_carrier_off/netif_carrier_on and rtnl_lock all entail
memory barriers, there is no need to have extra memory barriers around
them.

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
--
diff -r 7bf12da8a6ed -r c42c1f4bd148 
linux-2.6-xen-sparse/drivers/xen/netback/common.h
--- a/linux-2.6-xen-sparse/drivers/xen/netback/common.h Fri Jul 28 17:51:32 
2006 +1000
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/common.h Fri Jul 28 18:11:09 
2006 +1000
@@ -86,8 +86,6 @@ typedef struct netif_st {
        struct timer_list credit_timeout;
 
        /* Miscellaneous private stuff. */
-       enum { DISCONNECTED, DISCONNECTING, CONNECTED } status;
-       int active;
        struct list_head list;  /* scheduling list */
        atomic_t         refcnt;
        struct net_device *dev;
diff -r 7bf12da8a6ed -r c42c1f4bd148 
linux-2.6-xen-sparse/drivers/xen/netback/interface.c
--- a/linux-2.6-xen-sparse/drivers/xen/netback/interface.c      Fri Jul 28 
17:51:32 2006 +1000
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/interface.c      Fri Jul 28 
18:11:09 2006 +1000
@@ -36,28 +36,20 @@
 
 static void __netif_up(netif_t *netif)
 {
-       struct net_device *dev = netif->dev;
-       netif_tx_lock_bh(dev);
-       netif->active = 1;
-       netif_tx_unlock_bh(dev);
        enable_irq(netif->irq);
        netif_schedule_work(netif);
 }
 
 static void __netif_down(netif_t *netif)
 {
-       struct net_device *dev = netif->dev;
        disable_irq(netif->irq);
-       netif_tx_lock_bh(dev);
-       netif->active = 0;
-       netif_tx_unlock_bh(dev);
        netif_deschedule_work(netif);
 }
 
 static int net_open(struct net_device *dev)
 {
        netif_t *netif = netdev_priv(dev);
-       if (netif->status == CONNECTED)
+       if (netif_carrier_ok(dev))
                __netif_up(netif);
        netif_start_queue(dev);
        return 0;
@@ -67,7 +59,7 @@ static int net_close(struct net_device *
 {
        netif_t *netif = netdev_priv(dev);
        netif_stop_queue(dev);
-       if (netif->status == CONNECTED)
+       if (netif_carrier_ok(dev))
                __netif_down(netif);
        return 0;
 }
@@ -93,11 +85,12 @@ netif_t *netif_alloc(domid_t domid, unsi
                return ERR_PTR(-ENOMEM);
        }
 
+       netif_carrier_off(dev);
+
        netif = netdev_priv(dev);
        memset(netif, 0, sizeof(*netif));
        netif->domid  = domid;
        netif->handle = handle;
-       netif->status = DISCONNECTED;
        atomic_set(&netif->refcnt, 1);
        init_waitqueue_head(&netif->waiting_to_free);
        netif->dev = dev;
@@ -256,11 +249,9 @@ int netif_map(netif_t *netif, unsigned l
        netif->rx_req_cons_peek = 0;
 
        netif_get(netif);
-       wmb(); /* Other CPUs see new state before interface is started. */
 
        rtnl_lock();
-       netif->status = CONNECTED;
-       wmb();
+       netif_carrier_on(netif->dev);
        if (netif_running(netif->dev))
                __netif_up(netif);
        rtnl_unlock();
@@ -296,20 +287,13 @@ static void netif_free(netif_t *netif)
 
 void netif_disconnect(netif_t *netif)
 {
-       switch (netif->status) {
-       case CONNECTED:
+       if (netif_carrier_ok(netif->dev)) {
                rtnl_lock();
-               netif->status = DISCONNECTING;
-               wmb();
+               netif_carrier_off(netif->dev);
                if (netif_running(netif->dev))
                        __netif_down(netif);
                rtnl_unlock();
                netif_put(netif);
-               /* fall through */
-       case DISCONNECTED:
-               netif_free(netif);
-               break;
-       default:
-               BUG();
-       }
-}
+       }
+       netif_free(netif);
+}
diff -r 7bf12da8a6ed -r c42c1f4bd148 
linux-2.6-xen-sparse/drivers/xen/netback/netback.c
--- a/linux-2.6-xen-sparse/drivers/xen/netback/netback.c        Fri Jul 28 
17:51:32 2006 +1000
+++ b/linux-2.6-xen-sparse/drivers/xen/netback/netback.c        Fri Jul 28 
18:11:09 2006 +1000
@@ -143,7 +143,7 @@ int netif_be_start_xmit(struct sk_buff *
        BUG_ON(skb->dev != dev);
 
        /* Drop the packet if the target domain has no receive buffers. */
-       if (!netif->active || 
+       if (unlikely(!netif_running(dev) || !netif_carrier_ok(dev)) ||
            (netif->rx_req_cons_peek == netif->rx.sring->req_prod) ||
            ((netif->rx_req_cons_peek - netif->rx.rsp_prod_pvt) ==
             NET_RX_RING_SIZE))
@@ -404,7 +404,9 @@ static void add_to_net_schedule_list_tai
                return;
 
        spin_lock_irq(&net_schedule_list_lock);
-       if (!__on_net_schedule_list(netif) && netif->active) {
+       if (!__on_net_schedule_list(netif) &&
+           likely(netif_running(netif->dev) &&
+                  netif_carrier_ok(netif->dev))) {
                list_add_tail(&netif->list, &net_schedule_list);
                netif_get(netif);
        }

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel