From patchwork Mon May 4 10:08:03 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johannes Weiner X-Patchwork-Id: 21692 Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n44A9ntl019500 for ; Mon, 4 May 2009 10:09:50 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751007AbZEDKJr (ORCPT ); Mon, 4 May 2009 06:09:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751654AbZEDKJr (ORCPT ); Mon, 4 May 2009 06:09:47 -0400 Received: from cmpxchg.org ([85.214.51.133]:48142 "EHLO cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751007AbZEDKJq (ORCPT ); Mon, 4 May 2009 06:09:46 -0400 Date: Mon, 4 May 2009 12:08:03 +0200 From: Johannes Weiner To: Andrew Morton Cc: Magnus Damm , linux-media@vger.kernel.org, Hans Verkuil , Paul Mundt , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [patch 2/3] mm: use generic follow_pte() in follow_phys() Message-ID: <20090504100803.GA12726@cmpxchg.org> References: <20090501181449.GA8912@cmpxchg.org> <1241430874-12667-2-git-send-email-hannes@cmpxchg.org> Mime-Version: 1.0 Content-Disposition: inline In-Reply-To: <1241430874-12667-2-git-send-email-hannes@cmpxchg.org> Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On Mon, May 04, 2009 at 11:54:33AM +0200, Johannes Weiner wrote: > Signed-off-by: Johannes Weiner > --- > mm/memory.c | 37 ++++++------------------------------- > 1 files changed, 6 insertions(+), 31 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index a621319..aee167d 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3051,50 +3051,25 @@ int follow_phys(struct vm_area_struct *vma, > unsigned long address, unsigned int flags, > unsigned long *prot, resource_size_t *phys) > { > - pgd_t *pgd; > - pud_t *pud; > - pmd_t *pmd; > + int ret = -EINVAL; > pte_t *ptep, pte; > spinlock_t *ptl; > - resource_size_t phys_addr = 0; > - struct mm_struct *mm = vma->vm_mm; > - int ret = -EINVAL; > > if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) > goto out; > > - pgd = pgd_offset(mm, address); > - if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) > - goto out; > - > - pud = pud_offset(pgd, address); > - if (pud_none(*pud) || unlikely(pud_bad(*pud))) > - goto out; > - > - pmd = pmd_offset(pud, address); > - if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) > - goto out; > - > - /* We cannot handle huge page PFN maps. Luckily they don't exist. */ > - if (pmd_huge(*pmd)) > + if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) > goto out; > - > - ptep = pte_offset_map_lock(mm, pmd, address, &ptl); > - if (!ptep) > - goto out; > - > pte = *ptep; > - if (!pte_present(pte)) > - goto unlock; > + > if ((flags & FOLL_WRITE) && !pte_write(pte)) > goto unlock; > - phys_addr = pte_pfn(pte); > - phys_addr <<= PAGE_SHIFT; /* Shift here to avoid overflow on PAE */ > > *prot = pgprot_val(pte_pgprot(pte)); > - *phys = phys_addr; > - ret = 0; > + /* Shift here to avoid overflow on PAE */ > + *phys = pte_pfn(pte) << PAGE_SHIFT; Yuk, had my head in the butt here. Changed to *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; --- From: Johannes Weiner Subject: mm: use generic follow_pte() in follow_phys() Signed-off-by: Johannes Weiner --- mm/memory.c | 36 +++++------------------------------- 1 files changed, 5 insertions(+), 31 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index a621319..c047950 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3051,50 +3051,24 @@ int follow_phys(struct vm_area_struct *vma, unsigned long address, unsigned int flags, unsigned long *prot, resource_size_t *phys) { - pgd_t *pgd; - pud_t *pud; - pmd_t *pmd; + int ret = -EINVAL; pte_t *ptep, pte; spinlock_t *ptl; - resource_size_t phys_addr = 0; - struct mm_struct *mm = vma->vm_mm; - int ret = -EINVAL; if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) goto out; - pgd = pgd_offset(mm, address); - if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) - goto out; - - pud = pud_offset(pgd, address); - if (pud_none(*pud) || unlikely(pud_bad(*pud))) - goto out; - - pmd = pmd_offset(pud, address); - if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) - goto out; - - /* We cannot handle huge page PFN maps. Luckily they don't exist. */ - if (pmd_huge(*pmd)) + if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) goto out; - - ptep = pte_offset_map_lock(mm, pmd, address, &ptl); - if (!ptep) - goto out; - pte = *ptep; - if (!pte_present(pte)) - goto unlock; + if ((flags & FOLL_WRITE) && !pte_write(pte)) goto unlock; - phys_addr = pte_pfn(pte); - phys_addr <<= PAGE_SHIFT; /* Shift here to avoid overflow on PAE */ *prot = pgprot_val(pte_pgprot(pte)); - *phys = phys_addr; - ret = 0; + *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; + ret = 0; unlock: pte_unmap_unlock(ptep, ptl); out: