From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH v3 1/3] xen/arm: implement steal_page Date: Fri, 9 Aug 2013 11:46:28 -0400 Message-ID: <20130809154628.GH5637@phenom.dumpdata.com> References: <1375720856-8593-1-git-send-email-stefano.stabellini@eu.citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1375720856-8593-1-git-send-email-stefano.stabellini@eu.citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Stefano Stabellini Cc: xen-devel@lists.xensource.com, tim@xen.org, Ian.Campbell@citrix.com List-Id: xen-devel@lists.xenproject.org On Mon, Aug 05, 2013 at 05:40:54PM +0100, Stefano Stabellini wrote: > Signed-off-by: Stefano Stabellini > --- > xen/arch/arm/mm.c | 43 +++++++++++++++++++++++++++++++++++++++++++ > 1 files changed, 43 insertions(+), 0 deletions(-) > > diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c > index f301e65..ea64c03 100644 > --- a/xen/arch/arm/mm.c > +++ b/xen/arch/arm/mm.c > @@ -751,6 +751,49 @@ int donate_page(struct domain *d, struct page_info *page, unsigned int memflags) > int steal_page( > struct domain *d, struct page_info *page, unsigned int memflags) > { > + unsigned long x, y; > + bool_t drop_dom_ref = 0; Shouldn't this be true or false? > + > + spin_lock(&d->page_alloc_lock); > + > + if ( is_xen_heap_page(page) || (page_get_owner(page) != d) ) > + goto fail; > + > + /* > + * We require there is just one reference (PGC_allocated). We temporarily > + * drop this reference now so that we can safely swizzle the owner. > + */ > + y = page->count_info; > + do { > + x = y; > + if ( (x & (PGC_count_mask|PGC_allocated)) != (1 | PGC_allocated) ) > + goto fail; > + y = cmpxchg(&page->count_info, x, x & ~PGC_count_mask); > + } while ( y != x ); > + > + /* Swizzle the owner then reinstate the PGC_allocated reference. */ > + page_set_owner(page, NULL); > + y = page->count_info; > + do { > + x = y; > + BUG_ON((x & (PGC_count_mask|PGC_allocated)) != PGC_allocated); > + } while ( (y = cmpxchg(&page->count_info, x, x | 1)) != x ); > + > + /* Unlink from original owner. */ > + if ( !(memflags & MEMF_no_refcount) && !domain_adjust_tot_pages(d, -1) ) > + drop_dom_ref = 1; > + page_list_del(page, &d->page_list); > + > + spin_unlock(&d->page_alloc_lock); > + if ( unlikely(drop_dom_ref) ) > + put_domain(d); > + return 0; > + > + fail: > + spin_unlock(&d->page_alloc_lock); > + printk("Bad page %p: ed=%p(%u), sd=%p, caf=%08lx, taf=%lx\n", > + (void *)page_to_mfn(page), d, d->domain_id, > + page_get_owner(page), page->count_info, page->u.inuse.type_info); > return -1; > } > > -- > 1.7.2.5 > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel