Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934743Ab3DHCBo (ORCPT ); Sun, 7 Apr 2013 22:01:44 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:57975 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934716Ab3DHCBn (ORCPT ); Sun, 7 Apr 2013 22:01:43 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.7.4 Message-ID: <516224E4.5010409@jp.fujitsu.com> Date: Mon, 8 Apr 2013 11:01:08 +0900 From: Yasuaki Ishimatsu User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/20130328 Thunderbird/17.0.5 MIME-Version: 1.0 To: Toshi Kani CC: , , , , , , , , Subject: Re: [UPDATE][PATCH 2/3] resource: Add release_mem_region_adjustable() References: <1365031405-25206-1-git-send-email-toshi.kani@hp.com> In-Reply-To: <1365031405-25206-1-git-send-email-toshi.kani@hp.com> Content-Type: text/plain; charset="ISO-2022-JP" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5620 Lines: 175 Hi Toshi, 2013/04/04 8:23, 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 Reviewed-by : Yasuaki Ishimatsu One nitpick below. > --- > > Updated per code reviews from Yasuaki Ishimatsu, Ram Pai and > Gu Zheng. > > --- > include/linux/ioport.h | 2 + > kernel/resource.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 95 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..c7966c3 100644 > --- a/kernel/resource.c > +++ b/kernel/resource.c > @@ -1021,6 +1021,99 @@ 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 = -EINVAL; > + > + end = start + size - 1; > + if ((start < parent->start) || (end > parent->end)) > + return -EINVAL; "ret" is initialized to -EINVAL. So how about use it? Thanks, Yasuaki Ishimatsu > + > + 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; > + } > + > + if (!(res->flags & IORESOURCE_MEM)) > + break; > + > + if (!(res->flags & IORESOURCE_BUSY)) { > + p = &res->child; > + continue; > + } > + > + /* found the target resource; let's adjust accordingly */ > + if (res->start == start && res->end == end) { > + /* free the whole entry */ > + *p = res->sibling; > + kfree(res); > + ret = 0; > + } 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; > +} > + > /* > * 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/