From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 19D09C433FF for ; Thu, 8 Aug 2019 07:19:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DA821217F4 for ; Thu, 8 Aug 2019 07:19:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731449AbfHHHTc (ORCPT ); Thu, 8 Aug 2019 03:19:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50374 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725817AbfHHHTc (ORCPT ); Thu, 8 Aug 2019 03:19:32 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4A6F169081; Thu, 8 Aug 2019 07:19:31 +0000 (UTC) Received: from [10.36.117.55] (ovpn-117-55.ams2.redhat.com [10.36.117.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id 925F310016EB; Thu, 8 Aug 2019 07:19:29 +0000 (UTC) Subject: Re: [PATCH 2/2] s390/mm: Use refcount_t for refcount To: Chuhong Yuan Cc: Christian Borntraeger , Janosch Frank , Cornelia Huck , Heiko Carstens , Vasily Gorbik , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org References: <20190808071826.6649-1-hslester96@gmail.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwX4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq 7ut6OL64oAq+zsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+ xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABwsFl BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl SE+xAvmumFBY Organization: Red Hat GmbH Message-ID: <49f59848-00dd-660b-c192-a11beafbe277@redhat.com> Date: Thu, 8 Aug 2019 09:19:28 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190808071826.6649-1-hslester96@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 08 Aug 2019 07:19:31 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08.08.19 09:18, Chuhong Yuan wrote: > Reference counters are preferred to use refcount_t instead of > atomic_t. > This is because the implementation of refcount_t can prevent > overflows and detect possible use-after-free. > So convert atomic_t ref counters to refcount_t. > > Signed-off-by: Chuhong Yuan > --- > arch/s390/include/asm/gmap.h | 4 +++- > arch/s390/mm/gmap.c | 10 +++++----- > 2 files changed, 8 insertions(+), 6 deletions(-) > > diff --git a/arch/s390/include/asm/gmap.h b/arch/s390/include/asm/gmap.h > index fcbd638fb9f4..37f96b6f0e61 100644 > --- a/arch/s390/include/asm/gmap.h > +++ b/arch/s390/include/asm/gmap.h > @@ -9,6 +9,8 @@ > #ifndef _ASM_S390_GMAP_H > #define _ASM_S390_GMAP_H > > +#include > + > /* Generic bits for GMAP notification on DAT table entry changes. */ > #define GMAP_NOTIFY_SHADOW 0x2 > #define GMAP_NOTIFY_MPROT 0x1 > @@ -46,7 +48,7 @@ struct gmap { > struct radix_tree_root guest_to_host; > struct radix_tree_root host_to_guest; > spinlock_t guest_table_lock; > - atomic_t ref_count; > + refcount_t ref_count; > unsigned long *table; > unsigned long asce; > unsigned long asce_end; > diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c > index 39c3a6e3d262..cd8e03f04d6d 100644 > --- a/arch/s390/mm/gmap.c > +++ b/arch/s390/mm/gmap.c > @@ -67,7 +67,7 @@ static struct gmap *gmap_alloc(unsigned long limit) > INIT_RADIX_TREE(&gmap->host_to_rmap, GFP_ATOMIC); > spin_lock_init(&gmap->guest_table_lock); > spin_lock_init(&gmap->shadow_lock); > - atomic_set(&gmap->ref_count, 1); > + refcount_set(&gmap->ref_count, 1); > page = alloc_pages(GFP_KERNEL, CRST_ALLOC_ORDER); > if (!page) > goto out_free; > @@ -214,7 +214,7 @@ static void gmap_free(struct gmap *gmap) > */ > struct gmap *gmap_get(struct gmap *gmap) > { > - atomic_inc(&gmap->ref_count); > + refcount_inc(&gmap->ref_count); > return gmap; > } > EXPORT_SYMBOL_GPL(gmap_get); > @@ -227,7 +227,7 @@ EXPORT_SYMBOL_GPL(gmap_get); > */ > void gmap_put(struct gmap *gmap) > { > - if (atomic_dec_return(&gmap->ref_count) == 0) > + if (refcount_dec_and_test(&gmap->ref_count)) > gmap_free(gmap); > } > EXPORT_SYMBOL_GPL(gmap_put); > @@ -1594,7 +1594,7 @@ static struct gmap *gmap_find_shadow(struct gmap *parent, unsigned long asce, > continue; > if (!sg->initialized) > return ERR_PTR(-EAGAIN); > - atomic_inc(&sg->ref_count); > + refcount_inc(&sg->ref_count); > return sg; > } > return NULL; > @@ -1682,7 +1682,7 @@ struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce, > } > } > } > - atomic_set(&new->ref_count, 2); > + refcount_set(&new->ref_count, 2); > list_add(&new->list, &parent->children); > if (asce & _ASCE_REAL_SPACE) { > /* nothing to protect, return right away */ > Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb