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authorEduardo Otubo <otubo@redhat.com>2017-11-23 15:18:35 +0100
committerDavid S. Miller <davem@davemloft.net>2017-11-27 14:21:58 -0500
commit5b5971df3bc2775107ddad164018a8a8db633b81 (patch)
treedca1b7578a39cd189f67e2feba7d49d54ade1adc /drivers/net
parentd3fe1e0185cffabc9b6f73f246a5552b46af7131 (diff)
downloadlinux-5b5971df3bc2775107ddad164018a8a8db633b81.tar.bz2
xen-netfront: remove warning when unloading module
v2: * Replace busy wait with wait_event()/wake_up_all() * Cannot garantee that at the time xennet_remove is called, the xen_netback state will not be XenbusStateClosed, so added a condition for that * There's a small chance for the xen_netback state is XenbusStateUnknown by the time the xen_netfront switches to Closed, so added a condition for that. When unloading module xen_netfront from guest, dmesg would output warning messages like below: [ 105.236836] xen:grant_table: WARNING: g.e. 0x903 still in use! [ 105.236839] deferring g.e. 0x903 (pfn 0x35805) This problem relies on netfront and netback being out of sync. By the time netfront revokes the g.e.'s netback didn't have enough time to free all of them, hence displaying the warnings on dmesg. The trick here is to make netfront to wait until netback frees all the g.e.'s and only then continue to cleanup for the module removal, and this is done by manipulating both device states. Signed-off-by: Eduardo Otubo <otubo@redhat.com> Acked-by: Juergen Gross <jgross@suse.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/xen-netfront.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 8b8689c6d887..391432e2725d 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -87,6 +87,8 @@ struct netfront_cb {
/* IRQ name is queue name with "-tx" or "-rx" appended */
#define IRQ_NAME_SIZE (QUEUE_NAME_SIZE + 3)
+static DECLARE_WAIT_QUEUE_HEAD(module_unload_q);
+
struct netfront_stats {
u64 packets;
u64 bytes;
@@ -2021,10 +2023,12 @@ static void netback_changed(struct xenbus_device *dev,
break;
case XenbusStateClosed:
+ wake_up_all(&module_unload_q);
if (dev->state == XenbusStateClosed)
break;
/* Missed the backend's CLOSING state -- fallthrough */
case XenbusStateClosing:
+ wake_up_all(&module_unload_q);
xenbus_frontend_closed(dev);
break;
}
@@ -2130,6 +2134,20 @@ static int xennet_remove(struct xenbus_device *dev)
dev_dbg(&dev->dev, "%s\n", dev->nodename);
+ if (xenbus_read_driver_state(dev->otherend) != XenbusStateClosed) {
+ xenbus_switch_state(dev, XenbusStateClosing);
+ wait_event(module_unload_q,
+ xenbus_read_driver_state(dev->otherend) ==
+ XenbusStateClosing);
+
+ xenbus_switch_state(dev, XenbusStateClosed);
+ wait_event(module_unload_q,
+ xenbus_read_driver_state(dev->otherend) ==
+ XenbusStateClosed ||
+ xenbus_read_driver_state(dev->otherend) ==
+ XenbusStateUnknown);
+ }
+
xennet_disconnect_backend(info);
unregister_netdev(info->netdev);