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=-8.2 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 9D227C2D0CE for ; Tue, 21 Jan 2020 09:56:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A82420882 for ; Tue, 21 Jan 2020 09:56:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729316AbgAUJ4L (ORCPT ); Tue, 21 Jan 2020 04:56:11 -0500 Received: from foss.arm.com ([217.140.110.172]:40396 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728797AbgAUJ4L (ORCPT ); Tue, 21 Jan 2020 04:56:11 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DB75E1FB; Tue, 21 Jan 2020 01:56:10 -0800 (PST) Received: from [10.1.196.37] (e121345-lin.cambridge.arm.com [10.1.196.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6C87D3F6C4; Tue, 21 Jan 2020 01:56:07 -0800 (PST) Subject: Re: [Patch v3 3/3] iommu: avoid taking iova_rbtree_lock twice To: Cong Wang , iommu@lists.linux-foundation.org Cc: linux-kernel@vger.kernel.org, joro@8bytes.org, John Garry References: <20191218043951.10534-1-xiyou.wangcong@gmail.com> <20191218043951.10534-4-xiyou.wangcong@gmail.com> From: Robin Murphy Message-ID: <2ff1002c-28b3-a863-49d2-3eab5b5ea778@arm.com> Date: Tue, 21 Jan 2020 09:56:06 +0000 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191218043951.10534-4-xiyou.wangcong@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18/12/2019 4:39 am, Cong Wang wrote: > Both find_iova() and __free_iova() take iova_rbtree_lock, > there is no reason to take and release it twice inside > free_iova(). > > Fold them into one critical section by calling the unlock > versions instead. Makes sense to me. Reviewed-by: Robin Murphy > Cc: Joerg Roedel > Cc: John Garry > Signed-off-by: Cong Wang > --- > drivers/iommu/iova.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c > index 184d4c0e20b5..f46f8f794678 100644 > --- a/drivers/iommu/iova.c > +++ b/drivers/iommu/iova.c > @@ -390,10 +390,14 @@ EXPORT_SYMBOL_GPL(__free_iova); > void > free_iova(struct iova_domain *iovad, unsigned long pfn) > { > - struct iova *iova = find_iova(iovad, pfn); > + unsigned long flags; > + struct iova *iova; > > + spin_lock_irqsave(&iovad->iova_rbtree_lock, flags); > + iova = private_find_iova(iovad, pfn); > if (iova) > - __free_iova(iovad, iova); > + private_free_iova(iovad, iova); > + spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags); > > } > EXPORT_SYMBOL_GPL(free_iova); >