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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,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 CF59FECE564 for ; Tue, 18 Sep 2018 16:57:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9242B214C2 for ; Tue, 18 Sep 2018 16:57:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9242B214C2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=c-s.fr 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 S1730743AbeIRWbB (ORCPT ); Tue, 18 Sep 2018 18:31:01 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:34501 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730719AbeIRWbB (ORCPT ); Tue, 18 Sep 2018 18:31:01 -0400 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 42F8LP3nnPz9ttRf; Tue, 18 Sep 2018 18:57:33 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id 2Cg2mc7nfGhD; Tue, 18 Sep 2018 18:57:33 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 42F8LP3FsFz9ttRb; Tue, 18 Sep 2018 18:57:33 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 679618B80B; Tue, 18 Sep 2018 18:57:33 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id XW61nzgyzJ88; Tue, 18 Sep 2018 18:57:33 +0200 (CEST) Received: from pc16082vm.idsi0.si.c-s.fr (unknown [192.168.232.3]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 42E208B7F9; Tue, 18 Sep 2018 18:57:33 +0200 (CEST) Received: by pc16082vm.idsi0.si.c-s.fr (Postfix, from userid 0) id E70717192E; Tue, 18 Sep 2018 16:57:32 +0000 (UTC) Message-Id: <7efec0c76fa692513c806871151a7ae20e99fe05.1537288312.git.christophe.leroy@c-s.fr> In-Reply-To: References: From: Christophe Leroy Subject: [PATCH v4 15/20] powerpc/mm: Avoid useless lock with single page fragments To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , aneesh.kumar@linux.vnet.ibm.com Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Date: Tue, 18 Sep 2018 16:57:32 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is no point in taking the page table lock as pte_frag is always NULL when we have only one fragment. Signed-off-by: Christophe Leroy --- arch/powerpc/mm/pgtable-frag.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/powerpc/mm/pgtable-frag.c b/arch/powerpc/mm/pgtable-frag.c index bc924822dcd6..ab4910e92aaf 100644 --- a/arch/powerpc/mm/pgtable-frag.c +++ b/arch/powerpc/mm/pgtable-frag.c @@ -85,6 +85,9 @@ static pte_t *get_pte_from_cache(struct mm_struct *mm) { void *pte_frag, *ret; + if (PTE_FRAG_NR == 1) + return NULL; + spin_lock(&mm->page_table_lock); ret = mm->context.pte_frag; if (ret) { -- 2.13.3