From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934733Ab3DIFsh (ORCPT ); Tue, 9 Apr 2013 01:48:37 -0400 Received: from e34.co.us.ibm.com ([32.97.110.152]:48172 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751813Ab3DIFsg (ORCPT ); Tue, 9 Apr 2013 01:48:36 -0400 Date: Tue, 9 Apr 2013 13:48:25 +0800 From: Ram Pai To: Toshi Kani Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, guz.fnst@cn.fujitsu.com, tmac@hp.com, isimatu.yasuaki@jp.fujitsu.com, wency@cn.fujitsu.com, tangchen@cn.fujitsu.com, jiang.liu@huawei.com Subject: Re: [UPDATE][PATCH v2 2/3] resource: Add release_mem_region_adjustable() Message-ID: <20130409054825.GB7251@ram.oc3035372033.ibm.com> Reply-To: Ram Pai References: <1365457655-7453-1-git-send-email-toshi.kani@hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1365457655-7453-1-git-send-email-toshi.kani@hp.com> User-Agent: Mutt/1.5.20 (2009-12-10) X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13040905-2876-0000-0000-000007431719 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 08, 2013 at 03:47:35PM -0600, Toshi Kani wrote: > Added release_mem_region_adjustable(), which releases a requested > region from a currently busy memory resource. This interface > adjusts the matched memory resource accordingly even if the > requested region does not match exactly but still fits into. > > This new interface is intended for memory hot-delete. During > bootup, memory resources are inserted from the boot descriptor > table, such as EFI Memory Table and e820. Each memory resource > entry usually covers the whole contigous memory range. Memory > hot-delete request, on the other hand, may target to a particular > range of memory resource, and its size can be much smaller than > the whole contiguous memory. Since the existing release interfaces > like __release_region() require a requested region to be exactly > matched to a resource entry, they do not allow a partial resource > to be released. > > There is no change to the existing interfaces since their restriction > is valid for I/O resources. > > Signed-off-by: Toshi Kani > Reviewed-by : Yasuaki Ishimatsu > --- > > Added #ifdef CONFIG_MEMORY_HOTPLUG as suggested by Andrew Morton. > > --- > include/linux/ioport.h | 4 ++ > kernel/resource.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 100 insertions(+) > > diff --git a/include/linux/ioport.h b/include/linux/ioport.h > index 85ac9b9b..961d4dc 100644 > --- a/include/linux/ioport.h > +++ b/include/linux/ioport.h > @@ -192,6 +192,10 @@ extern struct resource * __request_region(struct resource *, > extern int __check_region(struct resource *, resource_size_t, resource_size_t); > extern void __release_region(struct resource *, resource_size_t, > resource_size_t); > +#ifdef CONFIG_MEMORY_HOTPLUG > +extern int release_mem_region_adjustable(struct resource *, resource_size_t, > + resource_size_t); > +#endif > > static inline int __deprecated check_region(resource_size_t s, > resource_size_t n) > diff --git a/kernel/resource.c b/kernel/resource.c > index ae246f9..25b945c 100644 > --- a/kernel/resource.c > +++ b/kernel/resource.c > @@ -1021,6 +1021,102 @@ void __release_region(struct resource *parent, resource_size_t start, > } > EXPORT_SYMBOL(__release_region); > > +#ifdef CONFIG_MEMORY_HOTPLUG > +/** > + * release_mem_region_adjustable - release a previously reserved memory region > + * @parent: parent resource descriptor > + * @start: resource start address > + * @size: resource region size > + * > + * This interface is intended for memory hot-delete. The requested region is > + * released from a currently busy memory resource. It adjusts the matched > + * busy memory resource accordingly even if the requested region does not > + * match exactly but still fits into. Existing children of the busy memory > + * resource must be immutable in this request. > + * > + * Note, when the busy memory resource gets split into two entries, the code > + * assumes that all children remain in the lower address entry for simplicity. > + * Enhance this logic when necessary. > + */ > +int release_mem_region_adjustable(struct resource *parent, > + resource_size_t start, resource_size_t size) > +{ > + struct resource **p; > + struct resource *res, *new; > + resource_size_t end; > + int ret = -EINVAL; > + > + end = start + size - 1; > + if ((start < parent->start) || (end > parent->end)) > + return ret; > + > + p = &parent->child; > + write_lock(&resource_lock); > + > + while ((res = *p)) { > + if (res->start >= end) > + break; > + > + /* look for the next resource if it does not fit into */ > + if (res->start > start || res->end < end) { > + p = &res->sibling; > + continue; > + } What if the resource overlaps. In other words, the res->start > start but res->end > end ? Also do you handle the case where the range spans across multiple adjacent resources? -- Ram Pai