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Commit 9587f44a authored by Alex Williamson's avatar Alex Williamson
Browse files

vfio: Convert container->group_lock to rwsem



All current users are writers, maintaining current mutual exclusion.
This lets us add read users next.

Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent aa2cba51
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+11 −10
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/string.h>
@@ -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;
}