Cool, thanks! So we will need only this (to be called from KVM), and that will be it, right?
int vfio_group_iommu_id_from_file(struct file *filep) ... On 06/22/2013 07:12 AM, Alex Williamson wrote: > vfio_group_fops_open attempts to limit concurrent sessions by > disallowing opens once group->container is set. This really doesn't > do what we want and allow for inconsistent behavior, for instance a > group can be opened twice, then a container set giving the user two > file descriptors to the group. But then it won't allow more to be > opened. There's not much reason to have the group opened multiple > times since most access is through devices or the container, so > complete what the original code intended and only allow a single > instance. > > Signed-off-by: Alex Williamson <[email protected]> > --- > drivers/vfio/vfio.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c > index 6d78736..d30f44d 100644 > --- a/drivers/vfio/vfio.c > +++ b/drivers/vfio/vfio.c > @@ -76,6 +76,7 @@ struct vfio_group { > struct notifier_block nb; > struct list_head vfio_next; > struct list_head container_next; > + atomic_t opened; > }; > > struct vfio_device { > @@ -206,6 +207,7 @@ static struct vfio_group *vfio_create_group(struct > iommu_group *iommu_group) > INIT_LIST_HEAD(&group->device_list); > mutex_init(&group->device_lock); > atomic_set(&group->container_users, 0); > + atomic_set(&group->opened, 0); > group->iommu_group = iommu_group; > > group->nb.notifier_call = vfio_iommu_group_notifier; > @@ -1236,12 +1238,22 @@ static long vfio_group_fops_compat_ioctl(struct file > *filep, > static int vfio_group_fops_open(struct inode *inode, struct file *filep) > { > struct vfio_group *group; > + int opened; > > group = vfio_group_get_from_minor(iminor(inode)); > if (!group) > return -ENODEV; > > + /* Do we need multiple instances of the group open? Seems not. */ > + opened = atomic_cmpxchg(&group->opened, 0, 1); > + if (opened) { > + vfio_group_put(group); > + return -EBUSY; > + } > + > + /* Is something still in use from a previous open? */ > if (group->container) { > + atomic_dec(&group->opened); > vfio_group_put(group); > return -EBUSY; > } > @@ -1259,6 +1271,8 @@ static int vfio_group_fops_release(struct inode *inode, > struct file *filep) > > vfio_group_try_dissolve_container(group); > > + atomic_dec(&group->opened); > + > vfio_group_put(group); > > return 0; > -- Alexey -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
