Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936730Ab3DRXdl (ORCPT ); Thu, 18 Apr 2013 19:33:41 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:36877 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936645Ab3DRXdk (ORCPT ); Thu, 18 Apr 2013 19:33:40 -0400 X-SecurityPolicyCheck: OK by SHieldMailChecker v1.7.4 Message-ID: <517082B9.7050708@jp.fujitsu.com> Date: Fri, 19 Apr 2013 08:33:13 +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: [Bug fix PATCH v4] Reusing a resource structure allocated by bootmem References: <516FB07C.9010603@jp.fujitsu.com> <1366295000.3824.47.camel@misato.fc.hp.com> In-Reply-To: <1366295000.3824.47.camel@misato.fc.hp.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3029 Lines: 130 Hi Toshi, 2013/04/18 23:23, Toshi Kani wrote: > On Thu, 2013-04-18 at 17:36 +0900, Yasuaki Ishimatsu wrote: >> When hot removing memory presented at boot time, following messages are shown: > : >> diff --git a/kernel/resource.c b/kernel/resource.c >> index 4aef886..637e8d2 100644 >> --- a/kernel/resource.c >> +++ b/kernel/resource.c >> @@ -21,6 +21,7 @@ >> #include >> #include >> #include >> +#include >> #include >> >> >> @@ -50,6 +51,16 @@ struct resource_constraint { >> >> static DEFINE_RWLOCK(resource_lock); >> >> +/* >> + * For memory hotplug, there is no way to free resource entries allocated >> + * by boot mem after the system is up. So for reusing the resource entry >> + * we need to remember the resource. >> + */ >> +struct resource bootmem_resource = { >> + .sibling = NULL, >> +}; > > This should be a pointer of struct resource and declared as static, such > as: > > static struct resource *bootmem_resource_free; O.K. I'll update it. > >> +static DEFINE_SPINLOCK(bootmem_resource_lock); >> + >> static void *r_next(struct seq_file *m, void *v, loff_t *pos) >> { >> struct resource *p = v; >> @@ -151,6 +162,39 @@ __initcall(ioresources_init); >> >> #endif /* CONFIG_PROC_FS */ >> >> +static void free_resource(struct resource *res) >> +{ >> + if (!res) >> + return; >> + >> + if (PageSlab(virt_to_head_page(res))) { >> + spin_lock(&bootmem_resource_lock); >> + res->sibling = bootmem_resource.sibling; >> + bootmem_resource.sibling = res; >> + spin_unlock(&bootmem_resource_lock); >> + } else { >> + kfree(res); >> + } >> +} > > I second with Johannes. I'll update it. > >> +static struct resource *get_resource(gfp_t flags) >> +{ >> + struct resource *res = NULL; >> + >> + spin_lock(&bootmem_resource_lock); >> + if (bootmem_resource.sibling) { >> + res = bootmem_resource.sibling; >> + bootmem_resource.sibling = res->sibling; >> + memset(res, 0, sizeof(struct resource)); >> + } >> + spin_unlock(&bootmem_resource_lock); > > I prefer to keep memset() outside of the spin lock. > > spin_lock(&bootmem_resource_lock); > if (..) { > : > spin_unlock(&bootmem_resource_lock); > memset(res, 0, sizeof(struct resource)); > } else { > spin_unlock(&bootmem_resource_lock); > res = kzalloc(sizeof(struct resource), flags); > } Hmm. It is a little ugly. How about it? spin_lock(&bootmem_resource_lock); if (bootmem_resource.sibling) { res = bootmem_resource.sibling; bootmem_resource.sibling = res->sibling; } spin_unlock(&bootmem_resource_lock); if (res) memset(res, 0, sizeof(struct resource)); else res = kzalloc(sizeof(struct resource), flags); Thanks, Yasuaki Ishimatsu > > Thanks, > -Toshi > >> + >> + >> + return res; >> +} >> + > > -- 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/