From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755786Ab3BETM6 (ORCPT ); Tue, 5 Feb 2013 14:12:58 -0500 Received: from mail-oa0-f47.google.com ([209.85.219.47]:37726 "EHLO mail-oa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751780Ab3BETMy (ORCPT ); Tue, 5 Feb 2013 14:12:54 -0500 Message-ID: <511159B3.8020000@gmail.com> Date: Tue, 05 Feb 2013 13:12:51 -0600 From: Rob Herring User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 MIME-Version: 1.0 To: Nicolas Pitre , Joonsoo Kim CC: Rob Herring , Russell King , js1304@gmail.com, Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v5 3/3] ARM: mm: use static_vm for managing static mapped areas References: <1360024314-1895-1-git-send-email-iamjoonsoo.kim@lge.com> <1360024314-1895-4-git-send-email-iamjoonsoo.kim@lge.com> <51114134.4070503@gmail.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/05/2013 12:13 PM, Nicolas Pitre wrote: > On Tue, 5 Feb 2013, Rob Herring wrote: > >> On 02/04/2013 10:44 PM, Nicolas Pitre wrote: >>> On Tue, 5 Feb 2013, Joonsoo Kim wrote: >>> >>>> A static mapped area is ARM-specific, so it is better not to use >>>> generic vmalloc data structure, that is, vmlist and vmlist_lock >>>> for managing static mapped area. And it causes some needless overhead and >>>> reducing this overhead is better idea. >>>> >>>> Now, we have newly introduced static_vm infrastructure. >>>> With it, we don't need to iterate all mapped areas. Instead, we just >>>> iterate static mapped areas. It helps to reduce an overhead of finding >>>> matched area. And architecture dependency on vmalloc layer is removed, >>>> so it will help to maintainability for vmalloc layer. >>>> >>>> Signed-off-by: Joonsoo Kim >> >> [snip] >> >>>> @@ -859,17 +864,12 @@ static void __init pci_reserve_io(void) >>>> { >>>> struct vm_struct *vm; >>>> unsigned long addr; >>>> + struct static_vm *svm; >>>> >>>> - /* we're still single threaded hence no lock needed here */ >>>> - for (vm = vmlist; vm; vm = vm->next) { >>>> - if (!(vm->flags & VM_ARM_STATIC_MAPPING)) >>>> - continue; >>>> - addr = (unsigned long)vm->addr; >>>> - addr &= ~(SZ_2M - 1); >>>> - if (addr == PCI_IO_VIRT_BASE) >>>> - return; >>>> + svm = find_static_vm_vaddr((void *)PCI_IO_VIRT_BASE); >>>> + if (svm) >>>> + return; >>>> >>>> - } >>>> >>>> vm_reserve_area_early(PCI_IO_VIRT_BASE, SZ_2M, pci_reserve_io); >>>> } >>> >>> The replacement code is not equivalent. I can't recall why the original >>> is as it is, but it doesn't look right to me. The 2MB round down >>> certainly looks suspicious. >> >> The PCI mapping is at a fixed, aligned 2MB mapping. If we find any >> virtual address within that region already mapped, it is an error. > > Ah, OK. This wasn't clear looking at the code. > >> We probably should have had a WARN here. > > Indeed. > >>> >>> The replacement code should be better. However I'd like you to get an >>> ACK from Rob Herring as well for this patch. >> >> It doesn't appear to me the above case is handled. The virt addr is >> checked whether it is within an existing mapping, but not whether the >> new mapping would overlap an existing mapping. It would be good to check >> for this generically rather than specifically for the PCI i/o mapping. > > Agreed. However that is checked already in vm_area_add_early(). > Therefore the overlap test here is redundant. Ah, right. In that case: Acked-by: Rob Herring Rob