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vfio: Convert container->group_lock to rwsem

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

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2013-04-25 16:12:38 -06:00
parent aa2cba51a0
commit 9587f44aa6
1 changed files with 11 additions and 10 deletions
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21
drivers/vfio/vfio.c
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@ -24,6 +24,7 @@
#include <linux/list.h> #include <linux/list.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/mutex.h> #include <linux/mutex.h>
#include <linux/rwsem.h>
#include <linux/sched.h> #include <linux/sched.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/string.h> #include <linux/string.h>
@ -57,7 +58,7 @@ struct vfio_iommu_driver {
struct vfio_container { struct vfio_container {
struct kref kref; struct kref kref;
struct list_head group_list; struct list_head group_list;
struct mutex group_lock; struct rw_semaphore group_lock;
struct vfio_iommu_driver *iommu_driver; struct vfio_iommu_driver *iommu_driver;
void *iommu_data; void *iommu_data;
}; };
@ -738,7 +739,7 @@ static long vfio_ioctl_check_extension(struct vfio_container *container,
return ret; return ret;
} }
/* hold container->group_lock */ /* hold write lock on container->group_lock */
static int __vfio_container_attach_groups(struct vfio_container *container, static int __vfio_container_attach_groups(struct vfio_container *container,
struct vfio_iommu_driver *driver, struct vfio_iommu_driver *driver,
void *data) void *data)
@ -769,7 +770,7 @@ static long vfio_ioctl_set_iommu(struct vfio_container *container,
struct vfio_iommu_driver *driver; struct vfio_iommu_driver *driver;
long ret = -ENODEV; long ret = -ENODEV;
mutex_lock(&container->group_lock); down_write(&container->group_lock);
/* /*
* The container is designed to be an unprivileged interface while * 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. * the container is deprivileged and returns to an unset state.
*/ */
if (list_empty(&container->group_list) || container->iommu_driver) { if (list_empty(&container->group_list) || container->iommu_driver) {
mutex_unlock(&container->group_lock); up_write(&container->group_lock);
return -EINVAL; return -EINVAL;
} }
@ -827,7 +828,7 @@ static long vfio_ioctl_set_iommu(struct vfio_container *container,
mutex_unlock(&vfio.iommu_drivers_lock); mutex_unlock(&vfio.iommu_drivers_lock);
skip_drivers_unlock: skip_drivers_unlock:
mutex_unlock(&container->group_lock); up_write(&container->group_lock);
return ret; return ret;
} }
@ -882,7 +883,7 @@ static int vfio_fops_open(struct inode *inode, struct file *filep)
return -ENOMEM; return -ENOMEM;
INIT_LIST_HEAD(&container->group_list); INIT_LIST_HEAD(&container->group_list);
mutex_init(&container->group_lock); init_rwsem(&container->group_lock);
kref_init(&container->kref); kref_init(&container->kref);
filep->private_data = container; 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_container *container = group->container;
struct vfio_iommu_driver *driver; struct vfio_iommu_driver *driver;
mutex_lock(&container->group_lock); down_write(&container->group_lock);
driver = container->iommu_driver; driver = container->iommu_driver;
if (driver) if (driver)
@ -979,7 +980,7 @@ static void __vfio_group_unset_container(struct vfio_group *group)
container->iommu_data = NULL; container->iommu_data = NULL;
} }
mutex_unlock(&container->group_lock); up_write(&container->group_lock);
vfio_container_put(container); 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; container = f.file->private_data;
WARN_ON(!container); /* fget ensures we don't race vfio_release */ 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; driver = container->iommu_driver;
if (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); atomic_inc(&group->container_users);
unlock_out: unlock_out:
mutex_unlock(&container->group_lock); up_write(&container->group_lock);
fdput(f); fdput(f);
return ret; return ret;
} }