Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933256Ab3DYWYS (ORCPT ); Thu, 25 Apr 2013 18:24:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:7083 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757955Ab3DYWYP (ORCPT ); Thu, 25 Apr 2013 18:24:15 -0400 Subject: [PATCH 1/2] vfio: Convert container->group_lock to rwsem To: alex.williamson@redhat.com From: Alex Williamson Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, mst@redhat.com Date: Thu, 25 Apr 2013 16:24:14 -0600 Message-ID: <20130425222414.14023.76000.stgit@bling.home> In-Reply-To: <20130425221546.14023.37372.stgit@bling.home> References: <20130425221546.14023.37372.stgit@bling.home> User-Agent: StGit/0.16 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3765 Lines: 116 All current users are writers, maintaining current mutual exclusion. This lets us add read users next. Signed-off-by: Alex Williamson --- drivers/vfio/vfio.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 21eddd9..073788e 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #include #include @@ -57,7 +58,7 @@ struct vfio_iommu_driver { struct vfio_container { struct kref kref; struct list_head group_list; - struct mutex group_lock; + struct rw_semaphore group_lock; struct vfio_iommu_driver *iommu_driver; void *iommu_data; }; @@ -738,7 +739,7 @@ static long vfio_ioctl_check_extension(struct vfio_container *container, return ret; } -/* hold container->group_lock */ +/* hold write lock on container->group_lock */ static int __vfio_container_attach_groups(struct vfio_container *container, struct vfio_iommu_driver *driver, void *data) @@ -769,7 +770,7 @@ static long vfio_ioctl_set_iommu(struct vfio_container *container, struct vfio_iommu_driver *driver; long ret = -ENODEV; - mutex_lock(&container->group_lock); + down_write(&container->group_lock); /* * The container is designed to be an unprivileged interface while @@ -780,7 +781,7 @@ static long vfio_ioctl_set_iommu(struct vfio_container *container, * the container is deprivileged and returns to an unset state. */ if (list_empty(&container->group_list) || container->iommu_driver) { - mutex_unlock(&container->group_lock); + up_write(&container->group_lock); return -EINVAL; } @@ -827,7 +828,7 @@ static long vfio_ioctl_set_iommu(struct vfio_container *container, mutex_unlock(&vfio.iommu_drivers_lock); skip_drivers_unlock: - mutex_unlock(&container->group_lock); + up_write(&container->group_lock); return ret; } @@ -882,7 +883,7 @@ static int vfio_fops_open(struct inode *inode, struct file *filep) return -ENOMEM; INIT_LIST_HEAD(&container->group_list); - mutex_init(&container->group_lock); + init_rwsem(&container->group_lock); kref_init(&container->kref); filep->private_data = container; @@ -961,7 +962,7 @@ static void __vfio_group_unset_container(struct vfio_group *group) struct vfio_container *container = group->container; struct vfio_iommu_driver *driver; - mutex_lock(&container->group_lock); + down_write(&container->group_lock); driver = container->iommu_driver; if (driver) @@ -979,7 +980,7 @@ static void __vfio_group_unset_container(struct vfio_group *group) container->iommu_data = NULL; } - mutex_unlock(&container->group_lock); + up_write(&container->group_lock); vfio_container_put(container); } @@ -1039,7 +1040,7 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd) container = f.file->private_data; WARN_ON(!container); /* fget ensures we don't race vfio_release */ - mutex_lock(&container->group_lock); + down_write(&container->group_lock); driver = container->iommu_driver; if (driver) { @@ -1057,7 +1058,7 @@ static int vfio_group_set_container(struct vfio_group *group, int container_fd) atomic_inc(&group->container_users); unlock_out: - mutex_unlock(&container->group_lock); + up_write(&container->group_lock); fdput(f); return ret; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/