[Xen-devel] [RFC PATCH V4 03/13] netback: add module get/put operations along with vif connect/disconnect.

[Wei Liu <wei.liu2@xxxxxxxxxx>]

If there is vif running and user unloads netback, it will certainly
cause problems -- guest's network interface just mysteriously stops
working.

disconnect function may get called by the generic framework even
before vif connects.

Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 drivers/net/xen-netback/interface.c |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/drivers/net/xen-netback/interface.c 
b/drivers/net/xen-netback/interface.c
index 1825629..4795c0f 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -312,6 +312,8 @@ int xenvif_connect(struct xenvif *vif, unsigned long 
tx_ring_ref,
        if (vif->irq)
                return 0;
 
+       __module_get(THIS_MODULE);
+
        err = xen_netbk_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);
        if (err < 0)
                goto err;
@@ -339,12 +341,15 @@ int xenvif_connect(struct xenvif *vif, unsigned long 
tx_ring_ref,
 err_unmap:
        xen_netbk_unmap_frontend_rings(vif);
 err:
+       module_put(THIS_MODULE);
        return err;
 }
 
 void xenvif_disconnect(struct xenvif *vif)
 {
        struct net_device *dev = vif->dev;
+       int need_module_put = 0;
+
        if (netif_carrier_ok(dev)) {
                rtnl_lock();
                netif_carrier_off(dev); /* discard queued packets */
@@ -359,12 +364,17 @@ void xenvif_disconnect(struct xenvif *vif)
 
        del_timer_sync(&vif->credit_timeout);
 
-       if (vif->irq)
+       if (vif->irq) {
                unbind_from_irqhandler(vif->irq, vif);
+               need_module_put = 1;
+       }
 
        unregister_netdev(vif->dev);
 
        xen_netbk_unmap_frontend_rings(vif);
 
        free_netdev(vif->dev);
+
+       if (need_module_put)
+               module_put(THIS_MODULE);
 }
-- 
1.7.2.5


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