Commit 3e55f8b3 authored by David Vrabel's avatar David Vrabel Committed by David S. Miller
Browse files

xen-netback: cancel the credit timer when taking the vif down



If the credit timer is left armed after calling
xen_netbk_remove_xenvif(), then it may fire and attempt to schedule
the vif which will then oops as vif->netbk == NULL.

This may happen both in the fatal error path and during normal
disconnection from the front end.

The sequencing during shutdown is critical to ensure that: a)
vif->netbk doesn't become unexpectedly NULL; and b) the net device/vif
is not freed.

1. Mark as unschedulable (netif_carrier_off()).
2. Synchronously cancel the timer.
3. Remove the vif from the schedule list.
4. Remove it from it netback thread group.
5. Wait for vif->refcnt to become 0.
Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
Acked-by: default avatarIan Campbell <ian.campbell@citrix.com>
Reported-by: default avatarChristopher S. Aker <caker@theshore.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 35876b5f
......@@ -132,6 +132,7 @@ static void xenvif_up(struct xenvif *vif)
static void xenvif_down(struct xenvif *vif)
{
disable_irq(vif->irq);
del_timer_sync(&vif->credit_timeout);
xen_netbk_deschedule_xenvif(vif);
xen_netbk_remove_xenvif(vif);
}
......@@ -363,8 +364,6 @@ void xenvif_disconnect(struct xenvif *vif)
atomic_dec(&vif->refcnt);
wait_event(vif->waiting_to_free, atomic_read(&vif->refcnt) == 0);
del_timer_sync(&vif->credit_timeout);
if (vif->irq)
unbind_from_irqhandler(vif->irq, vif);
......
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