From patchwork Fri Feb 7 19:42:29 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kirti Wankhede X-Patchwork-Id: 11371105 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 308E8924 for ; Fri, 7 Feb 2020 20:16:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0F0EE20715 for ; Fri, 7 Feb 2020 20:16:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="iqPqaE4P" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727162AbgBGUQc (ORCPT ); Fri, 7 Feb 2020 15:16:32 -0500 Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:11686 "EHLO hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727117AbgBGUQc (ORCPT ); Fri, 7 Feb 2020 15:16:32 -0500 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Fri, 07 Feb 2020 12:16:17 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Fri, 07 Feb 2020 12:16:31 -0800 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Fri, 07 Feb 2020 12:16:31 -0800 Received: from HQMAIL101.nvidia.com (172.20.187.10) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 7 Feb 2020 20:16:31 +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; Fri, 7 Feb 2020 20:16:24 +0000 From: Kirti Wankhede To: , CC: , , , , , , , , , , , , , , , , , , , , "Kirti Wankhede" Subject: [PATCH v12 Kernel 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages Date: Sat, 8 Feb 2020 01:12:29 +0530 Message-ID: <1581104554-10704-3-git-send-email-kwankhede@nvidia.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1581104554-10704-1-git-send-email-kwankhede@nvidia.com> References: <1581104554-10704-1-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=1581106577; bh=8nqDVFl6a2E+cBhlRJoQWVeBxlXKUInlVp9C6nTopcc=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:X-NVConfidentiality:MIME-Version: Content-Type; b=iqPqaE4P/2k4gUT/zkosJ1XAni0M4LEiTf8RcyN24oN4uwxVCYv+eIyerlhkeRPIB +KEbUUTIq95wdL7cO6WU9AWwkn+Eh97ZP+R3O3TdcH1Fvv4ZNQC7x1+sw4Z/V3v+ho Ikub+qAmxy/sDmzLMqQX6jKzDlb2qCpgp3EHFjWtB8ex9m4D7zj33khlAzw2a+dOdS YWpJ/JZkPaQ5rQ9xFj9UAWXgTl11/+s5pfLT+H/EYAN7eNBy0q2yjUkCgxtzbjtwlm f7QGg3BI4+ZNYxitZ5W8zfKtpwtbC7RYaFnyoBQvXKjFAHjS3Mav91RnfAmLGLtH7s N14fYguREUtQw== 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 --- 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 a177bf2c6683..d386461e5d11 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -111,7 +111,7 @@ 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 { @@ -232,7 +232,7 @@ 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; } @@ -250,7 +250,7 @@ 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; } @@ -258,7 +258,8 @@ 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); }