From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx185.postini.com [74.125.245.185]) by kanga.kvack.org (Postfix) with SMTP id ED1E06B00AF for ; Wed, 3 Apr 2013 03:39:04 -0400 (EDT) Message-ID: <515BDC3B.2000907@cn.fujitsu.com> Date: Wed, 03 Apr 2013 15:37:31 +0800 From: Gu Zheng MIME-Version: 1.0 Subject: Re: [PATCH 2/3] resource: Add release_mem_region_adjustable() References: <1364919450-8741-1-git-send-email-toshi.kani@hp.com> <1364919450-8741-3-git-send-email-toshi.kani@hp.com> In-Reply-To: <1364919450-8741-3-git-send-email-toshi.kani@hp.com> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Toshi Kani 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 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; p = &parent->child; write_lock(&resource_lock); while (res = *p) { if (res->start <= start && res->end >= end) { 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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