[Xen-devel] [PATCH net-next 1/2] xen-netback: add a vif-is-connected flag

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

Having applied my patch to separate vif disconnect and free, I ran into a
BUG when testing resume from S3 with a Windows frontend because the vif task
pointer was not cleared by xenvif_disconnect() and so a double call to this
function tries to stop the thread twice.
Rather than applying a point fix for that issue it seems better to introduce
a boolean to indicate whether the vif is connected or not such that repeated
calls to either xenvif_connect() or xenvif_disconnect() behave appropriately.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Cc: David Vrabel <david.vrabel@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 drivers/net/xen-netback/common.h    |    1 +
 drivers/net/xen-netback/interface.c |   24 +++++++++++++-----------
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 5715318..860d92c 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -169,6 +169,7 @@ struct xenvif {
 
        /* Miscellaneous private stuff. */
        struct net_device *dev;
+       bool connected;
 };
 
 static inline struct xenbus_device *xenvif_to_xenbus_device(struct xenvif *vif)
diff --git a/drivers/net/xen-netback/interface.c 
b/drivers/net/xen-netback/interface.c
index 01bb854..94b47f5 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -366,7 +366,7 @@ int xenvif_connect(struct xenvif *vif, unsigned long 
tx_ring_ref,
        int err = -ENOMEM;
 
        /* Already connected through? */
-       if (vif->tx_irq)
+       if (vif->connected)
                return 0;
 
        err = xenvif_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);
@@ -425,6 +425,7 @@ int xenvif_connect(struct xenvif *vif, unsigned long 
tx_ring_ref,
 
        wake_up_process(vif->task);
 
+       vif->connected = 1;
        return 0;
 
 err_rx_unbind:
@@ -453,23 +454,24 @@ void xenvif_carrier_off(struct xenvif *vif)
 
 void xenvif_disconnect(struct xenvif *vif)
 {
+       if (!vif->connected)
+               return;
+
        if (netif_carrier_ok(vif->dev))
                xenvif_carrier_off(vif);
 
-       if (vif->tx_irq) {
-               if (vif->tx_irq == vif->rx_irq)
-                       unbind_from_irqhandler(vif->tx_irq, vif);
-               else {
-                       unbind_from_irqhandler(vif->tx_irq, vif);
-                       unbind_from_irqhandler(vif->rx_irq, vif);
-               }
-               vif->tx_irq = 0;
+       if (vif->tx_irq == vif->rx_irq)
+               unbind_from_irqhandler(vif->tx_irq, vif);
+       else {
+               unbind_from_irqhandler(vif->tx_irq, vif);
+               unbind_from_irqhandler(vif->rx_irq, vif);
        }
 
-       if (vif->task)
-               kthread_stop(vif->task);
+       kthread_stop(vif->task);
 
        xenvif_unmap_frontend_rings(vif);
+
+       vif->connected = 0;
 }
 
 void xenvif_free(struct xenvif *vif)
-- 
1.7.10.4


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