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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 2/2] xen-netback: cancel the credit timer when taking the vif down
On 14/02/13 13:53, Wei Liu wrote: > On Thu, 2013-02-14 at 13:18 +0000, David Vrabel wrote: >> From: David Vrabel <david.vrabel@xxxxxxxxxx> >> >> 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: David Vrabel <david.vrabel@xxxxxxxxxx> > > You would need to reinitialize the timer in xenvif_up, given that user > might `ifconfig vifX.X down; ifconfig vifX.X up`. No. Deleted timers do not need to be reinitialized. The timer will be armed as usual with mod_timer() when credit is next exhausted. David _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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