Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932490Ab3DCUJf (ORCPT ); Wed, 3 Apr 2013 16:09:35 -0400 Received: from g6t0185.atlanta.hp.com ([15.193.32.62]:41178 "EHLO g6t0185.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762520Ab3DCUJe (ORCPT ); Wed, 3 Apr 2013 16:09:34 -0400 Message-ID: <1365019085.11159.115.camel@misato.fc.hp.com> Subject: Re: [PATCH 2/3] resource: Add release_mem_region_adjustable() From: Toshi Kani To: Gu Zheng Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxram@us.ibm.com, tmac@hp.com, isimatu.yasuaki@jp.fujitsu.com, wency@cn.fujitsu.com, tangchen@cn.fujitsu.com, jiang.liu@huawei.com Date: Wed, 03 Apr 2013 13:58:05 -0600 In-Reply-To: <515BDC3B.2000907@cn.fujitsu.com> References: <1364919450-8741-1-git-send-email-toshi.kani@hp.com> <1364919450-8741-3-git-send-email-toshi.kani@hp.com> <515BDC3B.2000907@cn.fujitsu.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.4 (3.4.4-2.fc17) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8993 Lines: 247 On Wed, 2013-04-03 at 15:37 +0800, Gu Zheng wrote: > On 04/03/2013 12:17 AM, 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 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 > > --- > > include/linux/ioport.h | 2 + > > kernel/resource.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++++ > > 2 files changed, 89 insertions(+) > > > > diff --git a/include/linux/ioport.h b/include/linux/ioport.h > > index 85ac9b9b..0fe1a82 100644 > > --- a/include/linux/ioport.h > > +++ b/include/linux/ioport.h > > @@ -192,6 +192,8 @@ 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); > > +extern int release_mem_region_adjustable(struct resource *, resource_size_t, > > + resource_size_t); > > > > 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..789f160 100644 > > --- a/kernel/resource.c > > +++ b/kernel/resource.c > > @@ -1021,6 +1021,93 @@ void __release_region(struct resource *parent, resource_size_t start, > > } > > EXPORT_SYMBOL(__release_region); > > > > +/** > > + * release_mem_region_adjustable - release a previously reserved memory region > > + * @parent: parent resource descriptor > > + * @start: resource start address > > + * @size: resource region size > > + * > > + * The requested region is released from a currently busy memory resource. > > + * It adjusts the matched busy memory resource accordingly 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 = 0; > > + > > + p = &parent->child; > > + end = start + size - 1; > > + > > + write_lock(&resource_lock); > > + > > + while ((res = *p)) { > > + if (res->start > start || res->end < end) { > > + p = &res->sibling; > > + continue; > > + } > > + > > + if (!(res->flags & IORESOURCE_MEM)) { > > + ret = -EINVAL; > > + break; > > + } > > + > > + if (!(res->flags & IORESOURCE_BUSY)) { > > + p = &res->child; > > + continue; > > + } > > + > > + if (res->start == start && res->end == end) { > > + /* free the whole entry */ > > + *p = res->sibling; > > + kfree(res); > > + } else if (res->start == start && res->end != end) { > > + /* adjust the start */ > > + ret = __adjust_resource(res, end+1, > > + res->end - end); > > + } else if (res->start != start && res->end == end) { > > + /* adjust the end */ > > + ret = __adjust_resource(res, res->start, > > + start - res->start); > > + } else { > > + /* split into two entries */ > > + new = kzalloc(sizeof(struct resource), GFP_KERNEL); > > + if (!new) { > > + ret = -ENOMEM; > > + break; > > + } > > + new->name = res->name; > > + new->start = end + 1; > > + new->end = res->end; > > + new->flags = res->flags; > > + new->parent = res->parent; > > + new->sibling = res->sibling; > > + new->child = NULL; > > + > > + ret = __adjust_resource(res, res->start, > > + start - res->start); > > + if (ret) { > > + kfree(new); > > + break; > > + } > > + res->sibling = new; > > + } > > + > > + break; > > + } > > + > > + write_unlock(&resource_lock); > > + return ret; > > +} > > + > > Hi Toshi, > What about the following small changes? Maybe it can make the code more rigorous~ > > Thanks, > Gu > > 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 = 0; > > end = start + size - 1; > if ((start < parent->start) || (end > parent->end)) > return -EINVAL; Sure, I will add this check. > > p = &parent->child; > > write_lock(&resource_lock); > > while (res = *p) { gcc actually complains if I do not put parentheses "((res = *p))" here. > if (res->start <= start && res->end >= end) { Yes, this way works the same as well. But, I'd prefer to avoid a big if-statement in a loop in order to keep indent small. I will add comments to make sure that the code is easy to follow. Thanks! -Toshi > if (!(res->flags & IORESOURCE_MEM)) { > ret = -EINVAL; > break; > } > > if (!(res->flags & IORESOURCE_BUSY)) { > p = &res->child; > continue; > } > > if (res->start == start && res->end == end) { > /* free the whole entry */ > *p = res->sibling; > kfree(res); > } else if (res->start == start && res->end != end) { > /* adjust the start */ > ret = __adjust_resource(res, end+1, > res->end - end); > } else if (res->start != start && res->end == end) { > /* adjust the end */ > ret = __adjust_resource(res, res->start, > start - res->start); > } else { > /* split into two entries */ > new = kzalloc(sizeof(struct resource), GFP_KERNEL); > if (!new) { > ret = -ENOMEM; > break; > } > new->name = res->name; > new->start = end + 1; > new->end = res->end; > new->flags = res->flags; > new->parent = res->parent; > new->sibling = res->sibling; > new->child = NULL; > > ret = __adjust_resource(res, res->start, > start - res->start); > if (ret) { > kfree(new); > break; > } > res->sibling = new; > } > break; > } > p = &res->sibling; > } > > write_unlock(&resource_lock); > return ret; > } > > > /* > > * Managed region resource > > */ > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/