From: David Vrabel <david.vrabel@citrix•com>
To: Wei Liu <wei.liu2@citrix•com>
Cc: "xen-devel@lists•xen.org" <xen-devel@lists•xen.org>,
Ian Campbell <Ian.Campbell@citrix•com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle•com>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
Jan Beulich <jbeulich@suse•com>,
"Wei Liu (3P)" <wei.liu@citrix•com>
Subject: Re: [Xen-devel] [PATCH 2/2] xen-netback: cancel the credit timer when taking the vif down
Date: Thu, 14 Feb 2013 13:56:24 +0000 [thread overview]
Message-ID: <511CED08.9080902@citrix.com> (raw)
In-Reply-To: <1360849999.16636.135.camel@zion.uk.xensource.com>
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@citrix•com>
>>
>> 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@citrix•com>
>
> 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
next prev parent reply other threads:[~2013-02-14 13:56 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-14 13:18 xen-netback: fix oopes during shutdown and error handling David Vrabel
2013-02-14 13:18 ` [PATCH 1/2] xen-netback: correctly return errors from netbk_count_requests() David Vrabel
2013-02-14 16:39 ` Ian Campbell
2013-02-14 13:18 ` [PATCH 2/2] xen-netback: cancel the credit timer when taking the vif down David Vrabel
2013-02-14 13:53 ` [Xen-devel] " Wei Liu
2013-02-14 13:56 ` David Vrabel [this message]
2013-02-14 14:10 ` Wei Liu
2013-02-14 14:15 ` Jan Beulich
2013-02-14 14:21 ` Wei Liu
2013-02-14 16:39 ` Ian Campbell
2013-02-14 16:48 ` [Xen-devel] " Wei Liu
2013-02-14 18:21 ` xen-netback: fix oopes during shutdown and error handling David Miller
2013-02-14 21:57 ` Christopher S. Aker
2013-02-15 8:45 ` [Xen-devel] " Ian Campbell
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