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=-4.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED 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 CEF35C04EB8 for ; Mon, 3 Dec 2018 00:06:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7F95B2054F for ; Mon, 3 Dec 2018 00:06:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="F+EDOSqU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7F95B2054F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725838AbeLCAG7 (ORCPT ); Sun, 2 Dec 2018 19:06:59 -0500 Received: from mail-pl1-f194.google.com ([209.85.214.194]:33808 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725785AbeLCAG7 (ORCPT ); Sun, 2 Dec 2018 19:06:59 -0500 Received: by mail-pl1-f194.google.com with SMTP id w4so5504049plz.1; Sun, 02 Dec 2018 16:06:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=message-id:subject:from:to:date:in-reply-to:references:mime-version :content-transfer-encoding; bh=VxXYlWNT8earf+JTvsyBbF6w33dswccpFK1H0CBc/tE=; b=F+EDOSqU6HG0sHLqaz003mjjDHj2tW90cynHhljxnB1BOEb0a6h5ZB0ZI2jmBunfMr x8yEBrtAG2h/AhDUbKdApZz6FsoTsekJE8zYch3DxwGYD4l6puNS+kx4NB9NP/k4oVdJ SZngTFmJCKxKR3QyCqA1kxpOiPsffrYxHRAiFfE+55dLms96Kl6wwXNfANBZ6GI4cSFO FTAnGzZ0fCjXWbFv21FoC4sn0o+KKXAKiUgbpaUhqcO3lepfh86gOwX8VKN/rm3Z/oC5 i3mMLdNstStZm/fTKzG3MuJTIboqWnAILqDOzxHsGJJ7hvKzxEaKdrSWAKB7Xr4AxS9G sfHw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:date:in-reply-to :references:mime-version:content-transfer-encoding; bh=VxXYlWNT8earf+JTvsyBbF6w33dswccpFK1H0CBc/tE=; b=npkjYIcrBdxFN6OY5a2a/aJwLIElae74w6qOd3+nW5hMSHv6eTi/WWs+iayT9VzBxa OsvgbJgyzcNrZHExqBIKFyb3ftFpfAf5PXgAQKJdi4ztO9NhEY8uocj6SY8Eh5kX2QDp aJu0+ypTK+UVnFOUk7zgS1vznSHhEOO4NjL/gvDxmCWc9Fb0/BVpu5vnqsvBi9fT8Buu CBfaKkNdz61VdTSAndlIp2xIHesINz1SmVauGjFVmyoGm1E5hkicj3zXugAT4j2ucR66 W5RTpII3PwWjX11vDhNFmElayzQZiOYRvvHRC+3QwscHY2Bhhu+4i/1h3qZBelaP0evA 1lxw== X-Gm-Message-State: AA+aEWY/R0VwKbwKvWp/KmK9lACcvn4X6L0qMN087CaLMazkP8ZQoTau 7bfzMEZubFPBPr8kZPKtD8oF6dgU X-Google-Smtp-Source: AFSGD/VIwhzJADVbXXeG1rhQP+GicVlfw7aLqW9PttImvpxgHk2Rv7xFdbd6b6syRuntaS4HjneR+w== X-Received: by 2002:a17:902:ba89:: with SMTP id k9mr14055351pls.189.1543795615698; Sun, 02 Dec 2018 16:06:55 -0800 (PST) Received: from surajjs2.ozlabs.ibm.com ([122.99.82.10]) by smtp.googlemail.com with ESMTPSA id 12sm11113999pgd.35.2018.12.02.16.06.52 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sun, 02 Dec 2018 16:06:54 -0800 (PST) Message-ID: <1543795610.7535.2.camel@gmail.com> Subject: Re: [PATCH] KVM: PPC: Book3S HV: NULL check before some freeing functions is not needed. From: Suraj Jitindar Singh To: Thomas Meyer , paulus@ozlabs.org, benh@kernel.crashing.org, mpe@ellerman.id.au, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Date: Mon, 03 Dec 2018 11:06:50 +1100 In-Reply-To: <1543760930051-2094322096-1-diffsplit-thomas@m3y3r.de> References: <1543760930050-1499171309-0-diffsplit-thomas@m3y3r.de> <1543760930051-2094322096-1-diffsplit-thomas@m3y3r.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.24.6 (3.24.6-1.fc26) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2018-12-02 at 21:52 +0100, Thomas Meyer wrote: > NULL check before some freeing functions is not needed. Technically true, however I think a comment should be added then to make it clearer to someone reading the code why this is ok. See below. Suraj. > > Signed-off-by: Thomas Meyer > --- > > diff -u -p a/arch/powerpc/kvm/book3s_hv_nested.c > b/arch/powerpc/kvm/book3s_hv_nested.c > --- a/arch/powerpc/kvm/book3s_hv_nested.c > +++ b/arch/powerpc/kvm/book3s_hv_nested.c > @@ -1252,8 +1252,7 @@ static long int __kvmhv_nested_page_faul > rmapp = &memslot->arch.rmap[gfn - memslot->base_gfn]; > ret = kvmppc_create_pte(kvm, gp->shadow_pgtable, pte, n_gpa, > level, > mmu_seq, gp->shadow_lpid, rmapp, > &n_rmap); > - if (n_rmap) > - kfree(n_rmap); > + kfree(n_rmap); e.g. /* n_rmap set to NULL in kvmppc_create_pte if reference preserved */ > if (ret == -EAGAIN) > ret = RESUME_GUEST; /* Let the guest try > again */ >