From patchwork Wed Mar 18 19:41:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kirti Wankhede X-Patchwork-Id: 11445883 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 44F9C6CA for ; Wed, 18 Mar 2020 20:15:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 24DDB2077A for ; Wed, 18 Mar 2020 20:15:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="E954hM/u" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726958AbgCRUPA (ORCPT ); Wed, 18 Mar 2020 16:15:00 -0400 Received: from hqnvemgate24.nvidia.com ([216.228.121.143]:11679 "EHLO hqnvemgate24.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726733AbgCRUPA (ORCPT ); Wed, 18 Mar 2020 16:15:00 -0400 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Wed, 18 Mar 2020 13:13:21 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Wed, 18 Mar 2020 13:14:59 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Wed, 18 Mar 2020 13:14:59 -0700 Received: from HQMAIL101.nvidia.com (172.20.187.10) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 18 Mar 2020 20:14:58 +0000 Received: from kwankhede-dev.nvidia.com (10.124.1.5) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Wed, 18 Mar 2020 20:14:52 +0000 From: Kirti Wankhede To: , CC: , , , , , , , , , , , , , , , , , , , , "Kirti Wankhede" Subject: [PATCH v14 Kernel 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages Date: Thu, 19 Mar 2020 01:11:09 +0530 Message-ID: <1584560474-19946-3-git-send-email-kwankhede@nvidia.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1584560474-19946-1-git-send-email-kwankhede@nvidia.com> References: <1584560474-19946-1-git-send-email-kwankhede@nvidia.com> X-NVConfidentiality: public MIME-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1584562401; bh=FmWokxxjiCUtfWFsp/qhJhc5S4LlTS5Wm3eAxSnwrTA=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:X-NVConfidentiality:MIME-Version: Content-Type; b=E954hM/ucHkgyOHsPRKpd9gwXTFW4hApQqzxHMFOr7jj1r85gS5U3LVU8FYVoRxz6 YbHmUY4GodVMIrYcVRuGuRZivsVHMNA0CIy5nGKU9kf/mhY5RKfktra0mWEiumfGkf 4Ks649fzoBhNZ3PeG6fNkWqhmJ4wQGE9EkcRnj/OHChpJkBO1Afs02GG7qXDs9pisc Fk5RNHWh0WiB5qOoPYTtIR4LECPjFXKWjbQ/zjyWAAEsB2QEkRFHS4yOVSpLPHDvRh x00dRnkpWTqT97MPSnKfywsAjXm6gKZCLul+lI0VrmNYVQcoDaewc/SYOPGGaN7CUb q9hc9osmc36TQ== Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org vfio_pfn.ref_count is always updated by holding iommu->lock, using atomic variable is overkill. Signed-off-by: Kirti Wankhede Reviewed-by: Neo Jia Reviewed-by: Eric Auger --- drivers/vfio/vfio_iommu_type1.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 9fdfae1cb17a..70aeab921d0f 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -112,7 +112,7 @@ struct vfio_pfn { struct rb_node node; dma_addr_t iova; /* Device address */ unsigned long pfn; /* Host pfn */ - atomic_t ref_count; + unsigned int ref_count; }; struct vfio_regions { @@ -233,7 +233,7 @@ static int vfio_add_to_pfn_list(struct vfio_dma *dma, dma_addr_t iova, vpfn->iova = iova; vpfn->pfn = pfn; - atomic_set(&vpfn->ref_count, 1); + vpfn->ref_count = 1; vfio_link_pfn(dma, vpfn); return 0; } @@ -251,7 +251,7 @@ static struct vfio_pfn *vfio_iova_get_vfio_pfn(struct vfio_dma *dma, struct vfio_pfn *vpfn = vfio_find_vpfn(dma, iova); if (vpfn) - atomic_inc(&vpfn->ref_count); + vpfn->ref_count++; return vpfn; } @@ -259,7 +259,8 @@ static int vfio_iova_put_vfio_pfn(struct vfio_dma *dma, struct vfio_pfn *vpfn) { int ret = 0; - if (atomic_dec_and_test(&vpfn->ref_count)) { + vpfn->ref_count--; + if (!vpfn->ref_count) { ret = put_pfn(vpfn->pfn, dma->prot); vfio_remove_from_pfn_list(dma, vpfn); }