xen-netback: enable user to unload netback module

This patch enables user to unload netback module, which is useful when user
wants to upgrade to a newer netback module without rebooting the host.

Netfront cannot handle netback removal event. As we cannot fix all possible
frontends we add module get / put along with vif get / put to avoid
mis-unloading of netback. To unload netback module, user needs to shutdown all
VMs or migrate them to another host or unplug all vifs before hand.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>¬
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 20 insertions, 0 deletions

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 295a9c267df4..2d9477fd900f 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -1949,5 +1949,25 @@ failed_init:
 
 module_init(netback_init);
 
+static void __exit netback_fini(void)
+{
+	int i, j;
+
+	xenvif_xenbus_fini();
+
+	for (i = 0; i < xen_netbk_group_nr; i++) {
+		struct xen_netbk *netbk = &xen_netbk[i];
+		del_timer_sync(&netbk->net_timer);
+		kthread_stop(netbk->task);
+		for (j = 0; j < MAX_PENDING_REQS; j++) {
+			if (netbk->mmap_pages[i])
+				__free_page(netbk->mmap_pages[i]);
+		}
+	}
+
+	vfree(xen_netbk);
+}
+module_exit(netback_fini);
+
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_ALIAS("xen-backend:vif");