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Re: [Xen-devel] [PATCH net-next] xen-netfront: clean up code in xennet_release_rx_bufs




On 2014-1-15 19:02, Andrew Bennieston wrote:
On 15/01/14 10:07, Wei Liu wrote:
On Fri, Jan 10, 2014 at 06:48:38AM +0800, Annie Li wrote:
Current netfront only grants pages for grant copy, not for grant transfer, so
remove corresponding transfer code and add receiving copy code in
xennet_release_rx_bufs.


This path seldom gets call -- not that many people unload xen-netfront
driver. If Annie has tested this patch and it works as expected I think
it's fine.

In XenServer we have seen a number of cases where unplugging and replugging VIFs results in leakage of grant references, eventually leading to a case where you cannot plug a VIF (after ~ 400 such cycles)...

It's worth pointing out, as far as this patch is concerned, that gnttab_end_foreign_access() can fail,

Just like what Wei mentioned, it is gnttab_end_foreign_access_ref here, right?

which is not taken into account here.

Good point, gnttab_end_foreign_access_ref fails for grant which is in use.

Thanks
Annie

Andrew.

I'm not netfront maintainer but I'm happy to add
Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
if Annie confirms she's tested this patch.

Wei.

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