From patchwork Thu Mar 19 20:16:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kirti Wankhede X-Patchwork-Id: 11448063 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 B2F9C139A for ; Thu, 19 Mar 2020 20:51:16 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8656E20774 for ; Thu, 19 Mar 2020 20:51:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="fwAiUI1h" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8656E20774 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:43036 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jF28J-0001Fp-Kj for patchwork-qemu-devel@patchwork.kernel.org; Thu, 19 Mar 2020 16:51:15 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42577) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jF27a-00085z-5G for qemu-devel@nongnu.org; Thu, 19 Mar 2020 16:50:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jF27Z-0003Ah-3D for qemu-devel@nongnu.org; Thu, 19 Mar 2020 16:50:30 -0400 Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:16425) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jF27Y-00038M-Ti for qemu-devel@nongnu.org; Thu, 19 Mar 2020 16:50:29 -0400 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Thu, 19 Mar 2020 13:50:14 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Thu, 19 Mar 2020 13:50:27 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Thu, 19 Mar 2020 13:50:27 -0700 Received: from HQMAIL105.nvidia.com (172.20.187.12) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 19 Mar 2020 20:50:27 +0000 Received: from kwankhede-dev.nvidia.com (10.124.1.5) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Thu, 19 Mar 2020 20:50:21 +0000 From: Kirti Wankhede To: , Subject: [PATCH v15 Kernel 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages Date: Fri, 20 Mar 2020 01:46:39 +0530 Message-ID: <1584649004-8285-3-git-send-email-kwankhede@nvidia.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1584649004-8285-1-git-send-email-kwankhede@nvidia.com> References: <1584649004-8285-1-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=1584651014; 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=fwAiUI1hZ0/nPvWTEtZeUftmL1+m/vDXGkQTiX1O+YT4VfIgLB5gHIdVqisDufLJZ 05VP3+cW6RbLaObx3w8Y8HoSjKn0DqTGuWOx44wAfDfBMoQGbkIIODrU9VJrd41Plp unHw2RgBL541yCgXMPM1BwunEUbwfn7jrTeg2kixeQWvKHMcX31D3bxJD5pkfI+lNu XJhBrZgfGUTj3thUPzheor2eg77JkChjN0Le787bqbliV8m7eksN6CmFFMJhFiTE47 cwVHma5LV1Koc+oLIOh/j71SXAr63b+Uf4jOMykF+Axhv8nJa35pZ3F3wQF1/hADoA Csg5JDnFYZe6A== X-detected-operating-system: by eggs.gnu.org: Windows 7 or 8 [fuzzy] X-Received-From: 216.228.121.65 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Zhengxiao.zx@Alibaba-inc.com, kevin.tian@intel.com, yi.l.liu@intel.com, yan.y.zhao@intel.com, kvm@vger.kernel.org, eskultet@redhat.com, ziye.yang@intel.com, qemu-devel@nongnu.org, cohuck@redhat.com, shuangtai.tst@alibaba-inc.com, dgilbert@redhat.com, zhi.a.wang@intel.com, mlevitsk@redhat.com, pasic@linux.ibm.com, aik@ozlabs.ru, Kirti Wankhede , eauger@redhat.com, felipe@nutanix.com, jonathan.davies@nutanix.com, changpeng.liu@intel.com, Ken.Xue@amd.com Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" 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); }