From patchwork Mon May 4 15:58:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kirti Wankhede X-Patchwork-Id: 1282819 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=2001:470:142::17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=nvidia.com header.i=@nvidia.com header.a=rsa-sha256 header.s=n1 header.b=dTeZ1CtE; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:470:142::17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 49G7t05rzZz9sP7 for ; Tue, 5 May 2020 02:41:44 +1000 (AEST) Received: from localhost ([::1]:48376 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jVeA2-0004V7-Jc for incoming@patchwork.ozlabs.org; Mon, 04 May 2020 12:41:42 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:47422) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jVe63-00067a-2q for qemu-devel@nongnu.org; Mon, 04 May 2020 12:37:35 -0400 Received: from hqnvemgate24.nvidia.com ([216.228.121.143]:17295) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jVe62-00008x-2G for qemu-devel@nongnu.org; Mon, 04 May 2020 12:37:34 -0400 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 04 May 2020 09:30:21 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Mon, 04 May 2020 09:32:29 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Mon, 04 May 2020 09:32:29 -0700 Received: from HQMAIL101.nvidia.com (172.20.187.10) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 4 May 2020 16:32:29 +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; Mon, 4 May 2020 16:32:22 +0000 From: Kirti Wankhede To: , Subject: [PATCH Kernel v18 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages Date: Mon, 4 May 2020 21:28:54 +0530 Message-ID: <1588607939-26441-3-git-send-email-kwankhede@nvidia.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1588607939-26441-1-git-send-email-kwankhede@nvidia.com> References: <1588607939-26441-1-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=1588609821; bh=uUgKJVCFdD4Zp7du3o0u/sQDLu1K2BjFd3xLP7hSugs=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:X-NVConfidentiality:MIME-Version: Content-Type; b=dTeZ1CtEAxZVOGcAv3K4pz7W6Hb34bil+8J6Rt0zCps/ZBLnxs5Qgl/JiKhSAP6Fd Xzj875AseBS9Z231eQjOI6l9WdIcwV2QmnQb7J9WtkDDFBJwq8oMl3Pm34IPPbhwaQ bSScXr9mpeqo+Z9pmE8CVTKMz5UxI3XIRhebnz/9RZ967+PHHq1M82syO14cg37z1B kU9dwLc8GMjWTUzkZZ87FRQNmWkgWJIE2Tmsc3Gq0gmy6D93xgNnNHAWQTkR5XSx5H QqP3dV752puWhMx77jbDgJUtGy6ORLOYONYe+wtQaUf53hH1BMiywXAGNocL1Zz/LJ yLtv4SSrI8Ltg== Received-SPF: pass client-ip=216.228.121.143; envelope-from=kwankhede@nvidia.com; helo=hqnvemgate24.nvidia.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/04 12:32:29 X-ACL-Warn: Detected OS = Windows 7 or 8 [fuzzy] X-Spam_score_int: -70 X-Spam_score: -7.1 X-Spam_bar: ------- X-Spam_report: (-7.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_HI=-5, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" vfio_pfn.ref_count is always updated while holding iommu->lock, using atomic variable is overkill. Signed-off-by: Kirti Wankhede Reviewed-by: Neo Jia Reviewed-by: Eric Auger Reviewed-by: Cornelia Huck --- 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 a0c60f895b24..fa735047b04d 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); }