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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

drivers/vfio/vfio.c

+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;

}