From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from fgwmail6.fujitsu.co.jp (fgwmail6.fujitsu.co.jp [192.51.44.36]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id B5FEC2C0087 for ; Wed, 26 Dec 2012 14:21:44 +1100 (EST) Received: from m2.gw.fujitsu.co.jp (unknown [10.0.50.72]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id F3E803EE0BD for ; Wed, 26 Dec 2012 12:21:42 +0900 (JST) Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id CE88A45DE74 for ; Wed, 26 Dec 2012 12:21:42 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id B04C045DE84 for ; Wed, 26 Dec 2012 12:21:42 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 9F80A1DB8040 for ; Wed, 26 Dec 2012 12:21:42 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.240.81.134]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 3B32C1DB8044 for ; Wed, 26 Dec 2012 12:21:42 +0900 (JST) Message-ID: <50DA6D04.8020906@jp.fujitsu.com> Date: Wed, 26 Dec 2012 12:20:36 +0900 From: Kamezawa Hiroyuki MIME-Version: 1.0 To: Tang Chen Subject: Re: [PATCH v5 03/14] memory-hotplug: remove redundant codes References: <1356350964-13437-1-git-send-email-tangchen@cn.fujitsu.com> <1356350964-13437-4-git-send-email-tangchen@cn.fujitsu.com> In-Reply-To: <1356350964-13437-4-git-send-email-tangchen@cn.fujitsu.com> Content-Type: text/plain; charset=ISO-2022-JP Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, linux-mm@kvack.org, paulus@samba.org, hpa@zytor.com, sparclinux@vger.kernel.org, cl@linux.com, linux-s390@vger.kernel.org, x86@kernel.org, linux-acpi@vger.kernel.org, isimatu.yasuaki@jp.fujitsu.com, linfeng@cn.fujitsu.com, mgorman@suse.de, kosaki.motohiro@jp.fujitsu.com, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, wency@cn.fujitsu.com, cmetcalf@tilera.com, wujianguo@huawei.com, yinghai@kernel.org, laijs@cn.fujitsu.com, linux-kernel@vger.kernel.org, minchan.kim@gmail.com, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , (2012/12/24 21:09), Tang Chen wrote: > From: Wen Congyang > > offlining memory blocks and checking whether memory blocks are offlined > are very similar. This patch introduces a new function to remove > redundant codes. > > Signed-off-by: Wen Congyang > --- > mm/memory_hotplug.c | 101 ++++++++++++++++++++++++++++----------------------- > 1 files changed, 55 insertions(+), 46 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index d43d97b..dbb04d8 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1381,20 +1381,14 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages) > return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ); > } > > -int remove_memory(u64 start, u64 size) please add explanation of this function here. If (*func) returns val other than 0, this function will fail and returns callback's return value...right ? > +static int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn, > + void *arg, int (*func)(struct memory_block *, void *)) > { > struct memory_block *mem = NULL; > struct mem_section *section; > - unsigned long start_pfn, end_pfn; > unsigned long pfn, section_nr; > int ret; > - int return_on_error = 0; > - int retry = 0; > - > - start_pfn = PFN_DOWN(start); > - end_pfn = start_pfn + PFN_DOWN(size); > > -repeat: Shouldn't we check lock is held here ? (VM_BUG_ON(!mutex_is_locked(&mem_hotplug_mutex); > for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) { > section_nr = pfn_to_section_nr(pfn); > if (!present_section_nr(section_nr)) > @@ -1411,22 +1405,61 @@ repeat: > if (!mem) > continue; > > - ret = offline_memory_block(mem); > + ret = func(mem, arg); > if (ret) { > - if (return_on_error) { > - kobject_put(&mem->dev.kobj); > - return ret; > - } else { > - retry = 1; > - } > + kobject_put(&mem->dev.kobj); > + return ret; > } > } > > if (mem) > kobject_put(&mem->dev.kobj); > > - if (retry) { > - return_on_error = 1; > + return 0; > +} > + > +static int offline_memory_block_cb(struct memory_block *mem, void *arg) > +{ > + int *ret = arg; > + int error = offline_memory_block(mem); > + > + if (error != 0 && *ret == 0) > + *ret = error; > + > + return 0; Always returns 0 and run through all mem blocks for scan-and-retry, right ? You need explanation here ! > +} > + > +static int is_memblock_offlined_cb(struct memory_block *mem, void *arg) > +{ > + int ret = !is_memblock_offlined(mem); > + > + if (unlikely(ret)) > + pr_warn("removing memory fails, because memory " > + "[%#010llx-%#010llx] is onlined\n", > + PFN_PHYS(section_nr_to_pfn(mem->start_section_nr)), > + PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1))-1); > + > + return ret; > +} > + > +int remove_memory(u64 start, u64 size) > +{ > + unsigned long start_pfn, end_pfn; > + int ret = 0; > + int retry = 1; > + > + start_pfn = PFN_DOWN(start); > + end_pfn = start_pfn + PFN_DOWN(size); > + > +repeat: please explan why you repeat here . > + walk_memory_range(start_pfn, end_pfn, &ret, > + offline_memory_block_cb); > + if (ret) { > + if (!retry) > + return ret; > + > + retry = 0; > + ret = 0; > goto repeat; > } > > @@ -1444,37 +1477,13 @@ repeat: > * memory blocks are offlined. > */ > > - for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) { > - section_nr = pfn_to_section_nr(pfn); > - if (!present_section_nr(section_nr)) > - continue; > - > - section = __nr_to_section(section_nr); > - /* same memblock? */ > - if (mem) > - if ((section_nr >= mem->start_section_nr) && > - (section_nr <= mem->end_section_nr)) > - continue; > - > - mem = find_memory_block_hinted(section, mem); > - if (!mem) > - continue; > - > - ret = is_memblock_offlined(mem); > - if (!ret) { > - pr_warn("removing memory fails, because memory " > - "[%#010llx-%#010llx] is onlined\n", > - PFN_PHYS(section_nr_to_pfn(mem->start_section_nr)), > - PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1)) - 1); > - > - kobject_put(&mem->dev.kobj); > - unlock_memory_hotplug(); > - return ret; > - } please explain what you do here. confirming all memory blocks are offlined before returning 0 ....right ? > + ret = walk_memory_range(start_pfn, end_pfn, NULL, > + is_memblock_offlined_cb); > + if (ret) { > + unlock_memory_hotplug(); > + return ret; > } > > - if (mem) > - kobject_put(&mem->dev.kobj); > unlock_memory_hotplug(); > > return 0; > Thanks, -Kame