From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [Xen-devel] [PATCH v4] xen/grant-table: Avoid m2p_override during mapping Date: Wed, 22 Jan 2014 10:58:00 +0000 Message-ID: <52DFA438.6050103@citrix.com> References: <1390335755-29328-1-git-send-email-zoltan.kiss@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: , , , , , , Stefano Stabellini To: Zoltan Kiss Return-path: Received: from smtp02.citrix.com ([66.165.176.63]:1098 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751773AbaAVK6F (ORCPT ); Wed, 22 Jan 2014 05:58:05 -0500 In-Reply-To: <1390335755-29328-1-git-send-email-zoltan.kiss@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: On 21/01/14 20:22, Zoltan Kiss wrote: > The grant mapping API does m2p_override unnecessarily: only gntdev needs it, > for blkback and future netback patches it just cause a lock contention, as > those pages never go to userspace. Therefore this series does the following: > - the original functions were renamed to __gnttab_[un]map_refs, with a new > parameter m2p_override > - based on m2p_override either they follow the original behaviour, or just set > the private flag and call set_phys_to_machine > - gnttab_[un]map_refs are now a wrapper to call __gnttab_[un]map_refs with > m2p_override false > - a new function gnttab_[un]map_refs_userspace provides the old behaviour > > v2: > - move the storing of the old mfn in page->index to gnttab_map_refs > - move the function header update to a separate patch > > v3: > - a new approach to retain old behaviour where it needed > - squash the patches into one > > v4: > - move out the common bits from m2p* functions, and pass pfn/mfn as parameter > - clear page->private before doing anything with the page, so m2p_find_override > won't race with this I would prune this version information out of the commit message. > Signed-off-by: Zoltan Kiss > Suggested-by: David Vrabel Reviewed-by: David Vrabel But I think this needs Stefano's ack. It would be useful to get this into 3.14 if possible. David