From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Liu Subject: Re: [Xen-devel] [PATCH net-next] xen-netfront: clean up code in xennet_release_rx_bufs Date: Wed, 15 Jan 2014 11:14:22 +0000 Message-ID: <20140115111422.GJ5698@zion.uk.xensource.com> References: <1389307718-2845-1-git-send-email-Annie.li@oracle.com> <20140115100743.GG5698@zion.uk.xensource.com> <52D66ADF.9070401@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Wei Liu , Annie Li , , , To: Andrew Bennieston Return-path: Received: from smtp.citrix.com ([66.165.176.89]:22864 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751350AbaAOLOY (ORCPT ); Wed, 15 Jan 2014 06:14:24 -0500 Content-Disposition: inline In-Reply-To: <52D66ADF.9070401@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Jan 15, 2014 at 11:02:55AM +0000, 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)... > OK, this makes sense. > It's worth pointing out, as far as this patch is concerned, that > gnttab_end_foreign_access() can fail, which is not taken into > account here. > How? gnttab_end_foreign_access doesn't return any error. The gref which cannot be freed right away will be added to a deferred list and handle later. Wei.