From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 564B1C433FE for ; Wed, 23 Nov 2022 15:01:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236841AbiKWPBn (ORCPT ); Wed, 23 Nov 2022 10:01:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35274 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236320AbiKWPBl (ORCPT ); Wed, 23 Nov 2022 10:01:41 -0500 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 59A5527DCA for ; Wed, 23 Nov 2022 07:01:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1669215701; x=1700751701; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=dr10QeVfQJUWkaHrfXcudR/HNo+6IV5vac1DJJlrnjw=; b=leKT9dDss5nf9bpnLpsItwCqCcHhIIywidLmjv93uf7sqRDx3Qc+X1FT GB1MitzYLUCORiIFk2BEkR7E3hwMqI2kpjpi3QkkFvJdRvG47UTdOaie0 P8Ivzv7PqleuGLvCjAqT3HYXb6fLqYGfnnqQkSTLLOM4pPu04HWczjqVy chITZKHxifw9F5i4NyfLKB3edkp2MfrALoWcZUWgaz1FVW8iWu8DtJytx xHkcpoAYzq+6omKrUNXLXFsJllqVzaL6jScD+CMTL9+jrfPMBKiMlwpQZ xxYGvri9ubob9QTygK8kVgRwjSGKcAf/Z5sNOHgTHi10PBAaVWv5P6pSl Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10540"; a="301642922" X-IronPort-AV: E=Sophos;i="5.96,187,1665471600"; d="scan'208";a="301642922" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Nov 2022 07:01:16 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10540"; a="674750872" X-IronPort-AV: E=Sophos;i="5.96,187,1665471600"; d="scan'208";a="674750872" Received: from 984fee00a4c6.jf.intel.com ([10.165.58.231]) by orsmga001.jf.intel.com with ESMTP; 23 Nov 2022 07:01:16 -0800 From: Yi Liu To: alex.williamson@redhat.com, jgg@nvidia.com Cc: kevin.tian@intel.com, eric.auger@redhat.com, cohuck@redhat.com, nicolinc@nvidia.com, yi.y.sun@linux.intel.com, chao.p.peng@linux.intel.com, mjrosato@linux.ibm.com, kvm@vger.kernel.org, yi.l.liu@intel.com Subject: [RFC 01/10] vfio: Simplify vfio_create_group() Date: Wed, 23 Nov 2022 07:01:04 -0800 Message-Id: <20221123150113.670399-2-yi.l.liu@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20221123150113.670399-1-yi.l.liu@intel.com> References: <20221123150113.670399-1-yi.l.liu@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Jason Gunthorpe The vfio.group_lock is now only used to serialize vfio_group creation and destruction, we don't need a micro-optimization of searching, unlocking, then allocating and searching again. Just hold the lock the whole time. Grabbed from: https://lore.kernel.org/kvm/20220922152338.2a2238fe.alex.williamson@redhat.com/ Signed-off-by: Jason Gunthorpe Signed-off-by: Alex Williamson Signed-off-by: Yi Liu --- drivers/vfio/vfio_main.c | 33 ++++++++++----------------------- 1 file changed, 10 insertions(+), 23 deletions(-) diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c index ea07b46dcea2..02f344441ddf 100644 --- a/drivers/vfio/vfio_main.c +++ b/drivers/vfio/vfio_main.c @@ -146,10 +146,12 @@ EXPORT_SYMBOL_GPL(vfio_device_set_open_count); * Group objects - create, release, get, put, search */ static struct vfio_group * -__vfio_group_get_from_iommu(struct iommu_group *iommu_group) +vfio_group_get_from_iommu(struct iommu_group *iommu_group) { struct vfio_group *group; + lockdep_assert_held(&vfio.group_lock); + /* * group->iommu_group from the vfio.group_list cannot be NULL * under the vfio.group_lock. @@ -163,17 +165,6 @@ __vfio_group_get_from_iommu(struct iommu_group *iommu_group) return NULL; } -static struct vfio_group * -vfio_group_get_from_iommu(struct iommu_group *iommu_group) -{ - struct vfio_group *group; - - mutex_lock(&vfio.group_lock); - group = __vfio_group_get_from_iommu(iommu_group); - mutex_unlock(&vfio.group_lock); - return group; -} - static void vfio_group_release(struct device *dev) { struct vfio_group *group = container_of(dev, struct vfio_group, dev); @@ -228,6 +219,8 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group, struct vfio_group *ret; int err; + lockdep_assert_held(&vfio.group_lock); + group = vfio_group_alloc(iommu_group, type); if (IS_ERR(group)) return group; @@ -240,26 +233,16 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group, goto err_put; } - mutex_lock(&vfio.group_lock); - - /* Did we race creating this group? */ - ret = __vfio_group_get_from_iommu(iommu_group); - if (ret) - goto err_unlock; - err = cdev_device_add(&group->cdev, &group->dev); if (err) { ret = ERR_PTR(err); - goto err_unlock; + goto err_put; } list_add(&group->vfio_next, &vfio.group_list); - mutex_unlock(&vfio.group_lock); return group; -err_unlock: - mutex_unlock(&vfio.group_lock); err_put: put_device(&group->dev); return ret; @@ -470,7 +453,9 @@ static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev, if (ret) goto out_put_group; + mutex_lock(&vfio.group_lock); group = vfio_create_group(iommu_group, type); + mutex_unlock(&vfio.group_lock); if (IS_ERR(group)) { ret = PTR_ERR(group); goto out_remove_device; @@ -519,9 +504,11 @@ static struct vfio_group *vfio_group_find_or_alloc(struct device *dev) return ERR_PTR(-EINVAL); } + mutex_lock(&vfio.group_lock); group = vfio_group_get_from_iommu(iommu_group); if (!group) group = vfio_create_group(iommu_group, VFIO_IOMMU); + mutex_unlock(&vfio.group_lock); /* The vfio_group holds a reference to the iommu_group */ iommu_group_put(iommu_group); -- 2.34.1