From patchwork Thu May 28 20:30:48 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kirti Wankhede X-Patchwork-Id: 11576905 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 BFCCF60D for ; Thu, 28 May 2020 21:04:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A637C208E4 for ; Thu, 28 May 2020 21:04:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="ArgAlmyA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407504AbgE1VEn (ORCPT ); Thu, 28 May 2020 17:04:43 -0400 Received: from hqnvemgate24.nvidia.com ([216.228.121.143]:8865 "EHLO hqnvemgate24.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2436498AbgE1VEc (ORCPT ); Thu, 28 May 2020 17:04:32 -0400 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Thu, 28 May 2020 14:03:01 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Thu, 28 May 2020 14:04:32 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Thu, 28 May 2020 14:04:32 -0700 Received: from HQMAIL105.nvidia.com (172.20.187.12) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 28 May 2020 21:04:22 +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, 28 May 2020 21:04:16 +0000 From: Kirti Wankhede To: , CC: , , , , , , , , , , , , , , , , , , , , Kirti Wankhede Subject: [PATCH Kernel v24 2/8] vfio iommu: Remove atomicity of ref_count of pinned pages Date: Fri, 29 May 2020 02:00:48 +0530 Message-ID: <1590697854-21364-3-git-send-email-kwankhede@nvidia.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1590697854-21364-1-git-send-email-kwankhede@nvidia.com> References: <1590697854-21364-1-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=1590699781; bh=q58lRQNXOJD9cHn7v7K1nm2nAWOG8aOUrmgD4LQlxAE=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:X-NVConfidentiality:MIME-Version: Content-Type; b=ArgAlmyADdm5Nj8/RZpw+XVqbe4fg8Lz+MAm9V0VVX13vn3gVAl8C2/4jpjH7lbv1 6kJlBEf8Eb6Mx3VwVIe7KvnwHjWwfEbP9LgZ1QWqkitLg12C5d7NlD3EGBvWi45Hfb G4GFUP/UOLYDlZCwm2tIgphFGjN2HrkC5XGBo2GiNfsCDPexDqFNb7x7BngxR9qqkb Bq+DkOyA1mcVjRHrWRwLCgGPG8LlcMRDlh1ubmiBXAqYfRHjiaUWKmVySJo04YxhLT ySWGk7zDLDCQ6Y8PNhZ5aYdvKQybJrN1Dqavyz/XHGNAskIkhhfbePrJSTyqeRGsod UHgR+2+MtinJA== Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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 Reviewed-by: Yan Zhao --- 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 5290c7a00bbc..fef7cd9a1747 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); }