diff options
| author | Jason Gunthorpe | 2022-05-16 20:41:18 -0300 |
|---|---|---|
| committer | Alex Williamson | 2022-05-17 13:07:09 -0600 |
| commit | c6f4860ef938606117961fac11d8d67497ab299b (patch) | |
| tree | 3f567232c420ea465993379fdff9c76f8d59c7aa /drivers/vfio | |
| parent | be8d3adae65cd44b6c299b796a5e1a0c24c54454 (diff) | |
vfio: Change struct vfio_group::opened from an atomic to bool
This is not a performance path, just use the group_rwsem to protect the
value.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/2-v2-d035a1842d81+1bf-vfio_group_locking_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'drivers/vfio')
| -rw-r--r-- | drivers/vfio/vfio.c | 46 |
1 files changed, 27 insertions, 19 deletions
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 4261eeec9e73..12d4b3efd463 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -73,7 +73,7 @@ struct vfio_group { struct mutex device_lock; struct list_head vfio_next; struct list_head container_next; - atomic_t opened; + bool opened; enum vfio_group_type type; unsigned int dev_counter; struct rw_semaphore group_rwsem; @@ -1213,30 +1213,30 @@ static int vfio_group_fops_open(struct inode *inode, struct file *filep) { struct vfio_group *group = container_of(inode->i_cdev, struct vfio_group, cdev); - int opened; + int ret; - /* users can be zero if this races with vfio_group_put() */ - if (!refcount_inc_not_zero(&group->users)) - return -ENODEV; + down_write(&group->group_rwsem); - if (group->type == VFIO_NO_IOMMU && !capable(CAP_SYS_RAWIO)) { - vfio_group_put(group); - return -EPERM; + /* users can be zero if this races with vfio_group_put() */ + if (!refcount_inc_not_zero(&group->users)) { + ret = -ENODEV; + goto err_unlock; } - /* 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; + if (group->type == VFIO_NO_IOMMU && !capable(CAP_SYS_RAWIO)) { + ret = -EPERM; + goto err_put; } - /* Is something still in use from a previous open? */ - if (group->container) { - atomic_dec(&group->opened); - vfio_group_put(group); - return -EBUSY; + /* + * Do we need multiple instances of the group open? Seems not. + * Is something still in use from a previous open? + */ + if (group->opened || group->container) { + ret = -EBUSY; + goto err_put; } + group->opened = true; /* Warn if previous user didn't cleanup and re-init to drop them */ if (WARN_ON(group->notifier.head)) @@ -1244,7 +1244,13 @@ static int vfio_group_fops_open(struct inode *inode, struct file *filep) filep->private_data = group; + up_write(&group->group_rwsem); return 0; +err_put: + vfio_group_put(group); +err_unlock: + up_write(&group->group_rwsem); + return ret; } static int vfio_group_fops_release(struct inode *inode, struct file *filep) @@ -1255,7 +1261,9 @@ static int vfio_group_fops_release(struct inode *inode, struct file *filep) vfio_group_try_dissolve_container(group); - atomic_dec(&group->opened); + down_write(&group->group_rwsem); + group->opened = false; + up_write(&group->group_rwsem); vfio_group_put(group); |