Subject: Re: [Xen-devel] [PATCH 2/8] netback: add module unload function

From: Andrew Cooper <[email-masked]>
Date: Mon, 4 Mar 2013 20:58:17 +0000

On 04/03/13 20:55, Konrad Rzeszutek Wilk wrote:
> On Fri, Feb 15, 2013 at 04:00:03PM +0000, Wei Liu wrote:
>> Enable users to unload netback module. Users should make sure there is not vif
>> runnig.
> 'sure there are no vif's running.'

If we are picking at grammar, no apostrophe in 'vifs'

~Andrew

>
> Any way of making this VIF part be automatic? Meaning that netback
> can figure out if there are VIFs running and if so don't unload
> all of the parts and just mention that you are leaking memory.
>
> This looks quite dangerous - meaning if there are guests running and
> we for fun do 'rmmod xen_netback' it looks like we could crash dom0?
>
>> Signed-off-by: Wei Liu <[email-masked]>
>> ---
>>  drivers/net/xen-netback/common.h  |    1 +
>>  drivers/net/xen-netback/netback.c |   18 ++++++++++++++++++
>>  drivers/net/xen-netback/xenbus.c  |    5 +++++
>>  3 files changed, 24 insertions(+)
>>
>> diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
>> index 9d7f172..35d8772 100644
>> --- a/drivers/net/xen-netback/common.h
>> +++ b/drivers/net/xen-netback/common.h
>> @@ -120,6 +120,7 @@ void xenvif_get(struct xenvif *vif);
>>  void xenvif_put(struct xenvif *vif);
>>  
>>  int xenvif_xenbus_init(void);
>> +void xenvif_xenbus_exit(void);
>>  
>>  int xenvif_schedulable(struct xenvif *vif);
>>  
>> diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
>> index db8d45a..de59098 100644
>> --- a/drivers/net/xen-netback/netback.c
>> +++ b/drivers/net/xen-netback/netback.c
>> @@ -1761,5 +1761,23 @@ failed_init:
>>  
>>  module_init(netback_init);
>>  
>> +static void __exit netback_exit(void)
>> +{
>> +	int group, i;
>> +	xenvif_xenbus_exit();
> You should check the return code of this function.
>
>> +	for (group = 0; group < xen_netbk_group_nr; group++) {
>> +		struct xen_netbk *netbk = &xen_netbk[group];
>> +		for (i = 0; i < MAX_PENDING_REQS; i++) {
>> +			if (netbk->mmap_pages[i])
>> +				__free_page(netbk->mmap_pages[i]);
>> +		}
>> +		del_timer_sync(&netbk->net_timer);
>> +		kthread_stop(netbk->task);
>> +	}
>> +	vfree(xen_netbk);
>> +}
>> +
>> +module_exit(netback_exit);
>> +
>>  MODULE_LICENSE("Dual BSD/GPL");
>>  MODULE_ALIAS("xen-backend:vif");
>> diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
>> index 410018c..65d14f2 100644
>> --- a/drivers/net/xen-netback/xenbus.c
>> +++ b/drivers/net/xen-netback/xenbus.c
>> @@ -485,3 +485,8 @@ int xenvif_xenbus_init(void)
>>  {
>>  	return xenbus_register_backend(&netback_driver);
>>  }
>> +
>> +void xenvif_xenbus_exit(void)
>> +{
>> +	return xenbus_unregister_driver(&netback_driver);
>> +}
>> -- 
>> 1.7.10.4
>>
>>
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>> http://lists.xen.org/xen-devel
>>
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