diff options
| author | Jason Gunthorpe <jgg@nvidia.com> | 2021-10-15 08:40:53 -0300 |
|---|---|---|
| committer | Alex Williamson <alex.williamson@redhat.com> | 2021-10-15 13:58:20 -0600 |
| commit | 2b678aa2f0990a25e15cdef66256a131566ecd2e (patch) | |
| tree | 96c10c15697f3d0e3f9db7ed695e12193024fb30 /drivers | |
| parent | 325a31c920309d2225311573a05c2f4dd402b2ed (diff) | |
| download | lwn-2b678aa2f0990a25e15cdef66256a131566ecd2e.tar.gz lwn-2b678aa2f0990a25e15cdef66256a131566ecd2e.zip | |
vfio: Use a refcount_t instead of a kref in the vfio_group
The next patch adds a struct device to the struct vfio_group, and it is
confusing/bad practice to have two krefs in the same struct. This kref is
controlling the period when the vfio_group is registered in sysfs, and
visible in the internal lookup. Switch it to a refcount_t instead.
The refcount_dec_and_mutex_lock() is still required because we need
atomicity of the list searches and sysfs presence.
Reviewed-by: Liu Yi L <yi.l.liu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/4-v3-2fdfe4ca2cc6+18c-vfio_group_cdev_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/vfio/vfio.c | 21 |
1 files changed, 9 insertions, 12 deletions
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 4abb2e5e1965..e313fa030b91 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -69,7 +69,7 @@ struct vfio_unbound_dev { }; struct vfio_group { - struct kref kref; + refcount_t users; int minor; atomic_t container_users; struct iommu_group *iommu_group; @@ -377,7 +377,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group, if (!group) return ERR_PTR(-ENOMEM); - kref_init(&group->kref); + refcount_set(&group->users, 1); INIT_LIST_HEAD(&group->device_list); mutex_init(&group->device_lock); INIT_LIST_HEAD(&group->unbound_list); @@ -433,10 +433,10 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group, return group; } -/* called with vfio.group_lock held */ -static void vfio_group_release(struct kref *kref) +static void vfio_group_put(struct vfio_group *group) { - struct vfio_group *group = container_of(kref, struct vfio_group, kref); + if (!refcount_dec_and_mutex_lock(&group->users, &vfio.group_lock)) + return; /* * These data structures all have paired operations that can only be @@ -454,15 +454,9 @@ static void vfio_group_release(struct kref *kref) vfio_group_unlock_and_free(group); } -static void vfio_group_put(struct vfio_group *group) -{ - kref_put_mutex(&group->kref, vfio_group_release, &vfio.group_lock); -} - -/* Assume group_lock or group reference is held */ static void vfio_group_get(struct vfio_group *group) { - kref_get(&group->kref); + refcount_inc(&group->users); } static struct vfio_group *vfio_group_get_from_minor(int minor) @@ -1657,6 +1651,9 @@ struct vfio_group *vfio_group_get_external_user(struct file *filep) if (ret) return ERR_PTR(ret); + /* + * Since the caller holds the fget on the file group->users must be >= 1 + */ vfio_group_get(group); return group; |