vfio: Change vfio_group->group_rwsem to a mutex
These days not much is using the read side:
- device first open
- ioctl_get_status
- device FD release
- check enforced_coherent
None of this is performance, so just make it into a normal mutex.
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/2-v1-917e3647f123+b1a-vfio_group_users_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
diff --git a/drivers/vfio/container.c b/drivers/vfio/container.c
index db7c071..d74164a 100644
--- a/drivers/vfio/container.c
+++ b/drivers/vfio/container.c
@@ -430,7 +430,7 @@ int vfio_container_attach_group(struct vfio_container *container,
struct vfio_iommu_driver *driver;
int ret = 0;
- lockdep_assert_held_write(&group->group_rwsem);
+ lockdep_assert_held(&group->group_lock);
if (group->type == VFIO_NO_IOMMU && !capable(CAP_SYS_RAWIO))
return -EPERM;
@@ -481,7 +481,7 @@ void vfio_group_detach_container(struct vfio_group *group)
struct vfio_container *container = group->container;
struct vfio_iommu_driver *driver;
- lockdep_assert_held_write(&group->group_rwsem);
+ lockdep_assert_held(&group->group_lock);
WARN_ON(group->container_users != 1);
down_write(&container->group_lock);
@@ -515,7 +515,7 @@ int vfio_device_assign_container(struct vfio_device *device)
{
struct vfio_group *group = device->group;
- lockdep_assert_held_write(&group->group_rwsem);
+ lockdep_assert_held(&group->group_lock);
if (!group->container || !group->container->iommu_driver ||
WARN_ON(!group->container_users))
@@ -531,11 +531,11 @@ int vfio_device_assign_container(struct vfio_device *device)
void vfio_device_unassign_container(struct vfio_device *device)
{
- down_write(&device->group->group_rwsem);
+ mutex_lock(&device->group->group_lock);
WARN_ON(device->group->container_users <= 1);
device->group->container_users--;
fput(device->group->opened_file);
- up_write(&device->group->group_rwsem);
+ mutex_unlock(&device->group->group_lock);
}
/*
