| Message ID | 20210826020122.1488002-6-desmondcheongzx@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm: update locking for modesetting | expand |
On Thu, Aug 26, 2021 at 10:01:20AM +0800, Desmond Cheong Zhi Xi wrote: > __drm_mode_object_find checks if the given drm file holds the required > lease on a object by calling _drm_lease_held. _drm_lease_held in turn > uses drm_file_get_master to access drm_file.master. > > However, in a future patch, the drm_file.master_lookup_lock in > drm_file_get_master will be replaced by drm_device.master_rwsem. This > is an issue for two reasons: > > 1. master_rwsem is sometimes already held when __drm_mode_object_find > is called, which leads to recursive locks on master_rwsem > > 2. drm_mode_object_find is sometimes called with the modeset_mutex > held, which leads to an inversion of the master_rwsem --> > modeset_mutex lock hierarchy > > To fix this, we make __drm_mode_object_find the locked version of > drm_mode_object_find, and wrap calls to __drm_mode_object_find with > locks on master_rwsem. This allows us to safely access drm_file.master > in _drm_lease_held (__drm_mode_object_find is its only caller) without > the use of drm_file_get_master. > > Functions that already lock master_rwsem are modified to call > __drm_mode_object_find, whereas functions that haven't locked > master_rwsem should call drm_mode_object_find. These two options > allow us to grab master_rwsem before modeset_mutex (such as in > drm_mode_get_obj_get_properties_ioctl). > > This new rule requires more extensive changes to three functions: > drn_connector_lookup, drm_crtc_find, and drm_plane_find. These > functions are only sometimes called with master_rwsem held. Hence, we > have to further split them into locked and unlocked versions that call > __drm_mode_object_find and drm_mode_object_find respectively. I think approach looks good, but the naming isn't so great. Usually __ prefix means "do not call directly, this is only exported for static inline and other helpers". For these the usual rule is to add a _locked or _unlocked suffix. I'd leave the normal _find functions as-is (since those take the lock) themselves, and annotate the _locked ones. Also same for the other lookup helpers. > > Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com> > --- > drivers/gpu/drm/drm_atomic_uapi.c | 7 ++--- > drivers/gpu/drm/drm_color_mgmt.c | 2 +- > drivers/gpu/drm/drm_crtc.c | 5 ++-- > drivers/gpu/drm/drm_framebuffer.c | 2 +- > drivers/gpu/drm/drm_lease.c | 21 +++++---------- > drivers/gpu/drm/drm_mode_object.c | 28 +++++++++++++++++--- > drivers/gpu/drm/drm_plane.c | 8 +++--- > drivers/gpu/drm/drm_property.c | 6 ++--- > drivers/gpu/drm/i915/display/intel_overlay.c | 2 +- > drivers/gpu/drm/i915/display/intel_sprite.c | 2 +- > drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 2 +- > include/drm/drm_connector.h | 23 ++++++++++++++++ > include/drm/drm_crtc.h | 22 +++++++++++++++ > include/drm/drm_mode_object.h | 3 +++ > include/drm/drm_plane.h | 20 ++++++++++++++ > 15 files changed, 118 insertions(+), 35 deletions(-) > > diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c > index 909f31833181..cda9a501cf74 100644 > --- a/drivers/gpu/drm/drm_atomic_uapi.c > +++ b/drivers/gpu/drm/drm_atomic_uapi.c > @@ -557,7 +557,7 @@ static int drm_atomic_plane_set_property(struct drm_plane *plane, > return -EINVAL; > > } else if (property == config->prop_crtc_id) { > - struct drm_crtc *crtc = drm_crtc_find(dev, file_priv, val); > + struct drm_crtc *crtc = __drm_crtc_find(dev, file_priv, val); > > if (val && !crtc) > return -EACCES; > @@ -709,7 +709,7 @@ static int drm_atomic_connector_set_property(struct drm_connector *connector, > int ret; > > if (property == config->prop_crtc_id) { > - struct drm_crtc *crtc = drm_crtc_find(dev, file_priv, val); > + struct drm_crtc *crtc = __drm_crtc_find(dev, file_priv, val); > > if (val && !crtc) > return -EACCES; > @@ -1385,7 +1385,8 @@ int drm_mode_atomic_ioctl(struct drm_device *dev, > goto out; > } > > - obj = drm_mode_object_find(dev, file_priv, obj_id, DRM_MODE_OBJECT_ANY); > + obj = __drm_mode_object_find(dev, file_priv, obj_id, > + DRM_MODE_OBJECT_ANY); > if (!obj) { > ret = -ENOENT; > goto out; > diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c > index bb14f488c8f6..9dcb2ccca3ab 100644 > --- a/drivers/gpu/drm/drm_color_mgmt.c > +++ b/drivers/gpu/drm/drm_color_mgmt.c > @@ -365,7 +365,7 @@ int drm_mode_gamma_set_ioctl(struct drm_device *dev, > if (!drm_core_check_feature(dev, DRIVER_MODESET)) > return -EOPNOTSUPP; > > - crtc = drm_crtc_find(dev, file_priv, crtc_lut->crtc_id); > + crtc = __drm_crtc_find(dev, file_priv, crtc_lut->crtc_id); > if (!crtc) > return -ENOENT; > > diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c > index 26a77a735905..b1279bb3fa61 100644 > --- a/drivers/gpu/drm/drm_crtc.c > +++ b/drivers/gpu/drm/drm_crtc.c > @@ -656,7 +656,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, > if (crtc_req->x & 0xffff0000 || crtc_req->y & 0xffff0000) > return -ERANGE; > > - crtc = drm_crtc_find(dev, file_priv, crtc_req->crtc_id); > + crtc = __drm_crtc_find(dev, file_priv, crtc_req->crtc_id); > if (!crtc) { > DRM_DEBUG_KMS("Unknown CRTC ID %d\n", crtc_req->crtc_id); > return -ENOENT; > @@ -787,7 +787,8 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, > goto out; > } > > - connector = drm_connector_lookup(dev, file_priv, out_id); > + connector = __drm_connector_lookup(dev, file_priv, > + out_id); > if (!connector) { > DRM_DEBUG_KMS("Connector id %d unknown\n", > out_id); > diff --git a/drivers/gpu/drm/drm_framebuffer.c b/drivers/gpu/drm/drm_framebuffer.c > index 07f5abc875e9..9c1db91b150d 100644 > --- a/drivers/gpu/drm/drm_framebuffer.c > +++ b/drivers/gpu/drm/drm_framebuffer.c > @@ -887,7 +887,7 @@ struct drm_framebuffer *drm_framebuffer_lookup(struct drm_device *dev, > struct drm_mode_object *obj; > struct drm_framebuffer *fb = NULL; > > - obj = __drm_mode_object_find(dev, file_priv, id, DRM_MODE_OBJECT_FB); > + obj = drm_mode_object_find(dev, file_priv, id, DRM_MODE_OBJECT_FB); I expect this to go boom, also for property and blob objects. These lookup functions can be called from the atomic_ioctl machinery, where we're already holding all kinds of locks. So grabbing the master_rwsem is not a good idea. We should always use the the drm_mode_object_find_unlocked for anything object which is not in the list of drm_mode_object_lease_required(). > if (obj) > fb = obj_to_fb(obj); > return fb; > diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c > index bed6f7636cbe..1b156c85d1c8 100644 > --- a/drivers/gpu/drm/drm_lease.c > +++ b/drivers/gpu/drm/drm_lease.c > @@ -105,22 +105,13 @@ static bool _drm_has_leased(struct drm_master *master, int id) > return false; > } > > -/* Called with idr_mutex held */ > +/* Called with idr_mutex and master_rwsem held */ Please verify this with lockdep_assert_held. The reason is that our locking gets rather funny here, because only for some types of objects do we need to check master status. drm_mode_object_lease_required() decides that. > bool _drm_lease_held(struct drm_file *file_priv, int id) > { > - bool ret; > - struct drm_master *master; > - > - if (!file_priv) > + if (!file_priv || !file_priv->master) > return true; > > - master = drm_file_get_master(file_priv); > - if (!master) > - return true; > - ret = _drm_lease_held_master(master, id); > - drm_master_put(&master); > - > - return ret; > + return _drm_lease_held_master(file_priv->master, id); > } > > bool drm_lease_held(struct drm_file *file_priv, int id) > @@ -391,9 +382,9 @@ static int fill_object_idr(struct drm_device *dev, > /* step one - get references to all the mode objects > and check for validity. */ > for (o = 0; o < object_count; o++) { > - objects[o] = drm_mode_object_find(dev, lessor_priv, > - object_ids[o], > - DRM_MODE_OBJECT_ANY); > + objects[o] = __drm_mode_object_find(dev, lessor_priv, > + object_ids[o], > + DRM_MODE_OBJECT_ANY); > if (!objects[o]) { > ret = -ENOENT; > goto out_free_objects; > diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c > index 86d9e907c0b2..90c23997aa53 100644 > --- a/drivers/gpu/drm/drm_mode_object.c > +++ b/drivers/gpu/drm/drm_mode_object.c > @@ -133,12 +133,27 @@ bool drm_mode_object_lease_required(uint32_t type) > } > } > > +/** > + * __drm_mode_object_find - look up a drm object with static lifetime > + * @dev: drm device > + * @file_priv: drm file > + * @id: id of the mode object > + * @type: type of the mode object > + * > + * This function is used to look up a modeset object. It will acquire a > + * reference for reference counted objects. This reference must be dropped > + * again by calling drm_mode_object_put(). > + * > + * Similar to drm_mode_object_find(), but called with &drm_device.master_rwsem > + * held. > + */ > struct drm_mode_object *__drm_mode_object_find(struct drm_device *dev, > struct drm_file *file_priv, > - uint32_t id, uint32_t type) > + u32 id, u32 type) > { > struct drm_mode_object *obj = NULL; > > + lockdep_assert_held_once(&dev->master_rwsem); > mutex_lock(&dev->mode_config.idr_mutex); > obj = idr_find(&dev->mode_config.object_idr, id); > if (obj && type != DRM_MODE_OBJECT_ANY && obj->type != type) > @@ -158,6 +173,7 @@ struct drm_mode_object *__drm_mode_object_find(struct drm_device *dev, > > return obj; > } > +EXPORT_SYMBOL(__drm_mode_object_find); > > /** > * drm_mode_object_find - look up a drm object with static lifetime > @@ -176,7 +192,9 @@ struct drm_mode_object *drm_mode_object_find(struct drm_device *dev, > { > struct drm_mode_object *obj = NULL; > > + down_read(&dev->master_rwsem); > obj = __drm_mode_object_find(dev, file_priv, id, type); > + up_read(&dev->master_rwsem); > return obj; > } > EXPORT_SYMBOL(drm_mode_object_find); > @@ -408,9 +426,12 @@ int drm_mode_obj_get_properties_ioctl(struct drm_device *dev, void *data, > if (!drm_core_check_feature(dev, DRIVER_MODESET)) > return -EOPNOTSUPP; > > + down_read(&dev->master_rwsem); > DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, ret); > > - obj = drm_mode_object_find(dev, file_priv, arg->obj_id, arg->obj_type); > + obj = __drm_mode_object_find(dev, file_priv, arg->obj_id, > + arg->obj_type); > + up_read(&dev->master_rwsem); > if (!obj) { > ret = -ENOENT; > goto out; > @@ -534,7 +555,8 @@ int drm_mode_obj_set_property_ioctl(struct drm_device *dev, void *data, > if (!drm_core_check_feature(dev, DRIVER_MODESET)) > return -EOPNOTSUPP; > > - arg_obj = drm_mode_object_find(dev, file_priv, arg->obj_id, arg->obj_type); > + arg_obj = __drm_mode_object_find(dev, file_priv, arg->obj_id, > + arg->obj_type); > if (!arg_obj) > return -ENOENT; > > diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c > index 82afb854141b..b5566167a798 100644 > --- a/drivers/gpu/drm/drm_plane.c > +++ b/drivers/gpu/drm/drm_plane.c > @@ -971,7 +971,7 @@ int drm_mode_setplane(struct drm_device *dev, void *data, > * First, find the plane, crtc, and fb objects. If not available, > * we don't bother to call the driver. > */ > - plane = drm_plane_find(dev, file_priv, plane_req->plane_id); > + plane = __drm_plane_find(dev, file_priv, plane_req->plane_id); > if (!plane) { > DRM_DEBUG_KMS("Unknown plane ID %d\n", > plane_req->plane_id); > @@ -986,7 +986,7 @@ int drm_mode_setplane(struct drm_device *dev, void *data, > return -ENOENT; > } > > - crtc = drm_crtc_find(dev, file_priv, plane_req->crtc_id); > + crtc = __drm_crtc_find(dev, file_priv, plane_req->crtc_id); > if (!crtc) { > drm_framebuffer_put(fb); > DRM_DEBUG_KMS("Unknown crtc ID %d\n", > @@ -1108,7 +1108,7 @@ static int drm_mode_cursor_common(struct drm_device *dev, > if (!req->flags || (~DRM_MODE_CURSOR_FLAGS & req->flags)) > return -EINVAL; > > - crtc = drm_crtc_find(dev, file_priv, req->crtc_id); > + crtc = __drm_crtc_find(dev, file_priv, req->crtc_id); > if (!crtc) { > DRM_DEBUG_KMS("Unknown CRTC ID %d\n", req->crtc_id); > return -ENOENT; > @@ -1229,7 +1229,7 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev, > if ((page_flip->flags & DRM_MODE_PAGE_FLIP_ASYNC) && !dev->mode_config.async_page_flip) > return -EINVAL; > > - crtc = drm_crtc_find(dev, file_priv, page_flip->crtc_id); > + crtc = __drm_crtc_find(dev, file_priv, page_flip->crtc_id); > if (!crtc) > return -ENOENT; > > diff --git a/drivers/gpu/drm/drm_property.c b/drivers/gpu/drm/drm_property.c > index 6c353c9dc772..9f04dcb81d07 100644 > --- a/drivers/gpu/drm/drm_property.c > +++ b/drivers/gpu/drm/drm_property.c > @@ -656,7 +656,7 @@ struct drm_property_blob *drm_property_lookup_blob(struct drm_device *dev, > struct drm_mode_object *obj; > struct drm_property_blob *blob = NULL; > > - obj = __drm_mode_object_find(dev, NULL, id, DRM_MODE_OBJECT_BLOB); > + obj = drm_mode_object_find(dev, NULL, id, DRM_MODE_OBJECT_BLOB); > if (obj) > blob = obj_to_blob(obj); > return blob; > @@ -919,8 +919,8 @@ bool drm_property_change_valid_get(struct drm_property *property, > if (value == 0) > return true; > > - *ref = __drm_mode_object_find(property->dev, NULL, value, > - property->values[0]); > + *ref = drm_mode_object_find(property->dev, NULL, value, > + property->values[0]); > return *ref != NULL; > } > > diff --git a/drivers/gpu/drm/i915/display/intel_overlay.c b/drivers/gpu/drm/i915/display/intel_overlay.c > index 7e3f5c6ca484..1d4af29e31c9 100644 > --- a/drivers/gpu/drm/i915/display/intel_overlay.c > +++ b/drivers/gpu/drm/i915/display/intel_overlay.c > @@ -1120,7 +1120,7 @@ int intel_overlay_put_image_ioctl(struct drm_device *dev, void *data, > return ret; > } > > - drmmode_crtc = drm_crtc_find(dev, file_priv, params->crtc_id); > + drmmode_crtc = __drm_crtc_find(dev, file_priv, params->crtc_id); > if (!drmmode_crtc) > return -ENOENT; > crtc = to_intel_crtc(drmmode_crtc); > diff --git a/drivers/gpu/drm/i915/display/intel_sprite.c b/drivers/gpu/drm/i915/display/intel_sprite.c > index 4ae9a7455b23..e19ef2d90bac 100644 > --- a/drivers/gpu/drm/i915/display/intel_sprite.c > +++ b/drivers/gpu/drm/i915/display/intel_sprite.c > @@ -1505,7 +1505,7 @@ int intel_sprite_set_colorkey_ioctl(struct drm_device *dev, void *data, > set->flags & I915_SET_COLORKEY_DESTINATION) > return -EINVAL; > > - plane = drm_plane_find(dev, file_priv, set->plane_id); > + plane = __drm_plane_find(dev, file_priv, set->plane_id); > if (!plane || plane->type != DRM_PLANE_TYPE_OVERLAY) > return -ENOENT; > > diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c > index 74fa41909213..d368b2bcb1fa 100644 > --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c > +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c > @@ -1862,7 +1862,7 @@ int vmw_kms_cursor_bypass_ioctl(struct drm_device *dev, void *data, > return 0; > } > > - crtc = drm_crtc_find(dev, file_priv, arg->crtc_id); > + crtc = __drm_crtc_find(dev, file_priv, arg->crtc_id); > if (!crtc) { > ret = -ENOENT; > goto out; > diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h > index 1647960c9e50..322c823583c7 100644 > --- a/include/drm/drm_connector.h > +++ b/include/drm/drm_connector.h > @@ -1591,6 +1591,29 @@ static inline u32 drm_connector_mask(const struct drm_connector *connector) > return 1 << connector->index; > } > > +/** > + * __drm_connector_lookup - lookup connector object > + * @dev: DRM device > + * @file_priv: drm file to check for lease against. > + * @id: connector object id > + * > + * This function looks up the connector object specified by id > + * add takes a reference to it. > + * > + * Similar to drm_connector_lookup(), but called with &drm_device.master_rwsem > + * held. > + */ > +static inline struct drm_connector *__drm_connector_lookup(struct drm_device *dev, > + struct drm_file *file_priv, > + uint32_t id) > +{ > + struct drm_mode_object *mo; > + > + mo = __drm_mode_object_find(dev, file_priv, id, > + DRM_MODE_OBJECT_CONNECTOR); > + return mo ? obj_to_connector(mo) : NULL; > +} > + > /** > * drm_connector_lookup - lookup connector object > * @dev: DRM device > diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h > index 13eeba2a750a..69df854dd322 100644 > --- a/include/drm/drm_crtc.h > +++ b/include/drm/drm_crtc.h > @@ -1283,6 +1283,28 @@ static inline uint32_t drm_crtc_mask(const struct drm_crtc *crtc) > int drm_mode_set_config_internal(struct drm_mode_set *set); > struct drm_crtc *drm_crtc_from_index(struct drm_device *dev, int idx); > > +/** > + * __drm_crtc_find - look up a CRTC object from its ID > + * @dev: DRM device > + * @file_priv: drm file to check for lease against. > + * @id: &drm_mode_object ID > + * > + * This can be used to look up a CRTC from its userspace ID. Only used by > + * drivers for legacy IOCTLs and interface, nowadays extensions to the KMS > + * userspace interface should be done using &drm_property. > + * > + * Similar to drm_crtc_find(), but called with &drm_device.master_rwsem held. > + */ > +static inline struct drm_crtc *__drm_crtc_find(struct drm_device *dev, > + struct drm_file *file_priv, > + uint32_t id) > +{ > + struct drm_mode_object *mo; > + > + mo = __drm_mode_object_find(dev, file_priv, id, DRM_MODE_OBJECT_CRTC); > + return mo ? obj_to_crtc(mo) : NULL; > +} > + > /** > * drm_crtc_find - look up a CRTC object from its ID > * @dev: DRM device > diff --git a/include/drm/drm_mode_object.h b/include/drm/drm_mode_object.h > index c34a3e8030e1..1906af9cae9b 100644 > --- a/include/drm/drm_mode_object.h > +++ b/include/drm/drm_mode_object.h > @@ -114,6 +114,9 @@ struct drm_object_properties { > return "(unknown)"; \ > } > > +struct drm_mode_object *__drm_mode_object_find(struct drm_device *dev, > + struct drm_file *file_priv, > + u32 id, u32 type); > struct drm_mode_object *drm_mode_object_find(struct drm_device *dev, > struct drm_file *file_priv, > uint32_t id, uint32_t type); > diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h > index fed97e35626f..49e35d3724c9 100644 > --- a/include/drm/drm_plane.h > +++ b/include/drm/drm_plane.h > @@ -842,6 +842,26 @@ int drm_mode_plane_set_obj_prop(struct drm_plane *plane, > struct drm_property *property, > uint64_t value); > > +/** > + * __drm_plane_find - find a &drm_plane > + * @dev: DRM device > + * @file_priv: drm file to check for lease against. > + * @id: plane id > + * > + * Returns the plane with @id, NULL if it doesn't exist. > + * > + * Similar to drm_plane_find(), but called with &drm_device.master_rwsem held. > + */ > +static inline struct drm_plane *__drm_plane_find(struct drm_device *dev, > + struct drm_file *file_priv, > + uint32_t id) > +{ > + struct drm_mode_object *mo; > + > + mo = __drm_mode_object_find(dev, file_priv, id, DRM_MODE_OBJECT_PLANE); > + return mo ? obj_to_plane(mo) : NULL; > +} > + > /** > * drm_plane_find - find a &drm_plane > * @dev: DRM device Aside from the one area for mode objects that cannoted be leased I think this looks correct. Sinc the spinlock+rwsem unification is a bit tricky, maybe you want to split out the patch series so that we can land the initial patches already? -Daniel > -- > 2.25.1 >
diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c index 909f31833181..cda9a501cf74 100644 --- a/drivers/gpu/drm/drm_atomic_uapi.c +++ b/drivers/gpu/drm/drm_atomic_uapi.c @@ -557,7 +557,7 @@ static int drm_atomic_plane_set_property(struct drm_plane *plane, return -EINVAL; } else if (property == config->prop_crtc_id) { - struct drm_crtc *crtc = drm_crtc_find(dev, file_priv, val); + struct drm_crtc *crtc = __drm_crtc_find(dev, file_priv, val); if (val && !crtc) return -EACCES; @@ -709,7 +709,7 @@ static int drm_atomic_connector_set_property(struct drm_connector *connector, int ret; if (property == config->prop_crtc_id) { - struct drm_crtc *crtc = drm_crtc_find(dev, file_priv, val); + struct drm_crtc *crtc = __drm_crtc_find(dev, file_priv, val); if (val && !crtc) return -EACCES; @@ -1385,7 +1385,8 @@ int drm_mode_atomic_ioctl(struct drm_device *dev, goto out; } - obj = drm_mode_object_find(dev, file_priv, obj_id, DRM_MODE_OBJECT_ANY); + obj = __drm_mode_object_find(dev, file_priv, obj_id, + DRM_MODE_OBJECT_ANY); if (!obj) { ret = -ENOENT; goto out; diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c index bb14f488c8f6..9dcb2ccca3ab 100644 --- a/drivers/gpu/drm/drm_color_mgmt.c +++ b/drivers/gpu/drm/drm_color_mgmt.c @@ -365,7 +365,7 @@ int drm_mode_gamma_set_ioctl(struct drm_device *dev, if (!drm_core_check_feature(dev, DRIVER_MODESET)) return -EOPNOTSUPP; - crtc = drm_crtc_find(dev, file_priv, crtc_lut->crtc_id); + crtc = __drm_crtc_find(dev, file_priv, crtc_lut->crtc_id); if (!crtc) return -ENOENT; diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index 26a77a735905..b1279bb3fa61 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -656,7 +656,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, if (crtc_req->x & 0xffff0000 || crtc_req->y & 0xffff0000) return -ERANGE; - crtc = drm_crtc_find(dev, file_priv, crtc_req->crtc_id); + crtc = __drm_crtc_find(dev, file_priv, crtc_req->crtc_id); if (!crtc) { DRM_DEBUG_KMS("Unknown CRTC ID %d\n", crtc_req->crtc_id); return -ENOENT; @@ -787,7 +787,8 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data, goto out; } - connector = drm_connector_lookup(dev, file_priv, out_id); + connector = __drm_connector_lookup(dev, file_priv, + out_id); if (!connector) { DRM_DEBUG_KMS("Connector id %d unknown\n", out_id); diff --git a/drivers/gpu/drm/drm_framebuffer.c b/drivers/gpu/drm/drm_framebuffer.c index 07f5abc875e9..9c1db91b150d 100644 --- a/drivers/gpu/drm/drm_framebuffer.c +++ b/drivers/gpu/drm/drm_framebuffer.c @@ -887,7 +887,7 @@ struct drm_framebuffer *drm_framebuffer_lookup(struct drm_device *dev, struct drm_mode_object *obj; struct drm_framebuffer *fb = NULL; - obj = __drm_mode_object_find(dev, file_priv, id, DRM_MODE_OBJECT_FB); + obj = drm_mode_object_find(dev, file_priv, id, DRM_MODE_OBJECT_FB); if (obj) fb = obj_to_fb(obj); return fb; diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c index bed6f7636cbe..1b156c85d1c8 100644 --- a/drivers/gpu/drm/drm_lease.c +++ b/drivers/gpu/drm/drm_lease.c @@ -105,22 +105,13 @@ static bool _drm_has_leased(struct drm_master *master, int id) return false; } -/* Called with idr_mutex held */ +/* Called with idr_mutex and master_rwsem held */ bool _drm_lease_held(struct drm_file *file_priv, int id) { - bool ret; - struct drm_master *master; - - if (!file_priv) + if (!file_priv || !file_priv->master) return true; - master = drm_file_get_master(file_priv); - if (!master) - return true; - ret = _drm_lease_held_master(master, id); - drm_master_put(&master); - - return ret; + return _drm_lease_held_master(file_priv->master, id); } bool drm_lease_held(struct drm_file *file_priv, int id) @@ -391,9 +382,9 @@ static int fill_object_idr(struct drm_device *dev, /* step one - get references to all the mode objects and check for validity. */ for (o = 0; o < object_count; o++) { - objects[o] = drm_mode_object_find(dev, lessor_priv, - object_ids[o], - DRM_MODE_OBJECT_ANY); + objects[o] = __drm_mode_object_find(dev, lessor_priv, + object_ids[o], + DRM_MODE_OBJECT_ANY); if (!objects[o]) { ret = -ENOENT; goto out_free_objects; diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c index 86d9e907c0b2..90c23997aa53 100644 --- a/drivers/gpu/drm/drm_mode_object.c +++ b/drivers/gpu/drm/drm_mode_object.c @@ -133,12 +133,27 @@ bool drm_mode_object_lease_required(uint32_t type) } } +/** + * __drm_mode_object_find - look up a drm object with static lifetime + * @dev: drm device + * @file_priv: drm file + * @id: id of the mode object + * @type: type of the mode object + * + * This function is used to look up a modeset object. It will acquire a + * reference for reference counted objects. This reference must be dropped + * again by calling drm_mode_object_put(). + * + * Similar to drm_mode_object_find(), but called with &drm_device.master_rwsem + * held. + */ struct drm_mode_object *__drm_mode_object_find(struct drm_device *dev, struct drm_file *file_priv, - uint32_t id, uint32_t type) + u32 id, u32 type) { struct drm_mode_object *obj = NULL; + lockdep_assert_held_once(&dev->master_rwsem); mutex_lock(&dev->mode_config.idr_mutex); obj = idr_find(&dev->mode_config.object_idr, id); if (obj && type != DRM_MODE_OBJECT_ANY && obj->type != type) @@ -158,6 +173,7 @@ struct drm_mode_object *__drm_mode_object_find(struct drm_device *dev, return obj; } +EXPORT_SYMBOL(__drm_mode_object_find); /** * drm_mode_object_find - look up a drm object with static lifetime @@ -176,7 +192,9 @@ struct drm_mode_object *drm_mode_object_find(struct drm_device *dev, { struct drm_mode_object *obj = NULL; + down_read(&dev->master_rwsem); obj = __drm_mode_object_find(dev, file_priv, id, type); + up_read(&dev->master_rwsem); return obj; } EXPORT_SYMBOL(drm_mode_object_find); @@ -408,9 +426,12 @@ int drm_mode_obj_get_properties_ioctl(struct drm_device *dev, void *data, if (!drm_core_check_feature(dev, DRIVER_MODESET)) return -EOPNOTSUPP; + down_read(&dev->master_rwsem); DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, ret); - obj = drm_mode_object_find(dev, file_priv, arg->obj_id, arg->obj_type); + obj = __drm_mode_object_find(dev, file_priv, arg->obj_id, + arg->obj_type); + up_read(&dev->master_rwsem); if (!obj) { ret = -ENOENT; goto out; @@ -534,7 +555,8 @@ int drm_mode_obj_set_property_ioctl(struct drm_device *dev, void *data, if (!drm_core_check_feature(dev, DRIVER_MODESET)) return -EOPNOTSUPP; - arg_obj = drm_mode_object_find(dev, file_priv, arg->obj_id, arg->obj_type); + arg_obj = __drm_mode_object_find(dev, file_priv, arg->obj_id, + arg->obj_type); if (!arg_obj) return -ENOENT; diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c index 82afb854141b..b5566167a798 100644 --- a/drivers/gpu/drm/drm_plane.c +++ b/drivers/gpu/drm/drm_plane.c @@ -971,7 +971,7 @@ int drm_mode_setplane(struct drm_device *dev, void *data, * First, find the plane, crtc, and fb objects. If not available, * we don't bother to call the driver. */ - plane = drm_plane_find(dev, file_priv, plane_req->plane_id); + plane = __drm_plane_find(dev, file_priv, plane_req->plane_id); if (!plane) { DRM_DEBUG_KMS("Unknown plane ID %d\n", plane_req->plane_id); @@ -986,7 +986,7 @@ int drm_mode_setplane(struct drm_device *dev, void *data, return -ENOENT; } - crtc = drm_crtc_find(dev, file_priv, plane_req->crtc_id); + crtc = __drm_crtc_find(dev, file_priv, plane_req->crtc_id); if (!crtc) { drm_framebuffer_put(fb); DRM_DEBUG_KMS("Unknown crtc ID %d\n", @@ -1108,7 +1108,7 @@ static int drm_mode_cursor_common(struct drm_device *dev, if (!req->flags || (~DRM_MODE_CURSOR_FLAGS & req->flags)) return -EINVAL; - crtc = drm_crtc_find(dev, file_priv, req->crtc_id); + crtc = __drm_crtc_find(dev, file_priv, req->crtc_id); if (!crtc) { DRM_DEBUG_KMS("Unknown CRTC ID %d\n", req->crtc_id); return -ENOENT; @@ -1229,7 +1229,7 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev, if ((page_flip->flags & DRM_MODE_PAGE_FLIP_ASYNC) && !dev->mode_config.async_page_flip) return -EINVAL; - crtc = drm_crtc_find(dev, file_priv, page_flip->crtc_id); + crtc = __drm_crtc_find(dev, file_priv, page_flip->crtc_id); if (!crtc) return -ENOENT; diff --git a/drivers/gpu/drm/drm_property.c b/drivers/gpu/drm/drm_property.c index 6c353c9dc772..9f04dcb81d07 100644 --- a/drivers/gpu/drm/drm_property.c +++ b/drivers/gpu/drm/drm_property.c @@ -656,7 +656,7 @@ struct drm_property_blob *drm_property_lookup_blob(struct drm_device *dev, struct drm_mode_object *obj; struct drm_property_blob *blob = NULL; - obj = __drm_mode_object_find(dev, NULL, id, DRM_MODE_OBJECT_BLOB); + obj = drm_mode_object_find(dev, NULL, id, DRM_MODE_OBJECT_BLOB); if (obj) blob = obj_to_blob(obj); return blob; @@ -919,8 +919,8 @@ bool drm_property_change_valid_get(struct drm_property *property, if (value == 0) return true; - *ref = __drm_mode_object_find(property->dev, NULL, value, - property->values[0]); + *ref = drm_mode_object_find(property->dev, NULL, value, + property->values[0]); return *ref != NULL; } diff --git a/drivers/gpu/drm/i915/display/intel_overlay.c b/drivers/gpu/drm/i915/display/intel_overlay.c index 7e3f5c6ca484..1d4af29e31c9 100644 --- a/drivers/gpu/drm/i915/display/intel_overlay.c +++ b/drivers/gpu/drm/i915/display/intel_overlay.c @@ -1120,7 +1120,7 @@ int intel_overlay_put_image_ioctl(struct drm_device *dev, void *data, return ret; } - drmmode_crtc = drm_crtc_find(dev, file_priv, params->crtc_id); + drmmode_crtc = __drm_crtc_find(dev, file_priv, params->crtc_id); if (!drmmode_crtc) return -ENOENT; crtc = to_intel_crtc(drmmode_crtc); diff --git a/drivers/gpu/drm/i915/display/intel_sprite.c b/drivers/gpu/drm/i915/display/intel_sprite.c index 4ae9a7455b23..e19ef2d90bac 100644 --- a/drivers/gpu/drm/i915/display/intel_sprite.c +++ b/drivers/gpu/drm/i915/display/intel_sprite.c @@ -1505,7 +1505,7 @@ int intel_sprite_set_colorkey_ioctl(struct drm_device *dev, void *data, set->flags & I915_SET_COLORKEY_DESTINATION) return -EINVAL; - plane = drm_plane_find(dev, file_priv, set->plane_id); + plane = __drm_plane_find(dev, file_priv, set->plane_id); if (!plane || plane->type != DRM_PLANE_TYPE_OVERLAY) return -ENOENT; diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c index 74fa41909213..d368b2bcb1fa 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c @@ -1862,7 +1862,7 @@ int vmw_kms_cursor_bypass_ioctl(struct drm_device *dev, void *data, return 0; } - crtc = drm_crtc_find(dev, file_priv, arg->crtc_id); + crtc = __drm_crtc_find(dev, file_priv, arg->crtc_id); if (!crtc) { ret = -ENOENT; goto out; diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h index 1647960c9e50..322c823583c7 100644 --- a/include/drm/drm_connector.h +++ b/include/drm/drm_connector.h @@ -1591,6 +1591,29 @@ static inline u32 drm_connector_mask(const struct drm_connector *connector) return 1 << connector->index; } +/** + * __drm_connector_lookup - lookup connector object + * @dev: DRM device + * @file_priv: drm file to check for lease against. + * @id: connector object id + * + * This function looks up the connector object specified by id + * add takes a reference to it. + * + * Similar to drm_connector_lookup(), but called with &drm_device.master_rwsem + * held. + */ +static inline struct drm_connector *__drm_connector_lookup(struct drm_device *dev, + struct drm_file *file_priv, + uint32_t id) +{ + struct drm_mode_object *mo; + + mo = __drm_mode_object_find(dev, file_priv, id, + DRM_MODE_OBJECT_CONNECTOR); + return mo ? obj_to_connector(mo) : NULL; +} + /** * drm_connector_lookup - lookup connector object * @dev: DRM device diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index 13eeba2a750a..69df854dd322 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -1283,6 +1283,28 @@ static inline uint32_t drm_crtc_mask(const struct drm_crtc *crtc) int drm_mode_set_config_internal(struct drm_mode_set *set); struct drm_crtc *drm_crtc_from_index(struct drm_device *dev, int idx); +/** + * __drm_crtc_find - look up a CRTC object from its ID + * @dev: DRM device + * @file_priv: drm file to check for lease against. + * @id: &drm_mode_object ID + * + * This can be used to look up a CRTC from its userspace ID. Only used by + * drivers for legacy IOCTLs and interface, nowadays extensions to the KMS + * userspace interface should be done using &drm_property. + * + * Similar to drm_crtc_find(), but called with &drm_device.master_rwsem held. + */ +static inline struct drm_crtc *__drm_crtc_find(struct drm_device *dev, + struct drm_file *file_priv, + uint32_t id) +{ + struct drm_mode_object *mo; + + mo = __drm_mode_object_find(dev, file_priv, id, DRM_MODE_OBJECT_CRTC); + return mo ? obj_to_crtc(mo) : NULL; +} + /** * drm_crtc_find - look up a CRTC object from its ID * @dev: DRM device diff --git a/include/drm/drm_mode_object.h b/include/drm/drm_mode_object.h index c34a3e8030e1..1906af9cae9b 100644 --- a/include/drm/drm_mode_object.h +++ b/include/drm/drm_mode_object.h @@ -114,6 +114,9 @@ struct drm_object_properties { return "(unknown)"; \ } +struct drm_mode_object *__drm_mode_object_find(struct drm_device *dev, + struct drm_file *file_priv, + u32 id, u32 type); struct drm_mode_object *drm_mode_object_find(struct drm_device *dev, struct drm_file *file_priv, uint32_t id, uint32_t type); diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h index fed97e35626f..49e35d3724c9 100644 --- a/include/drm/drm_plane.h +++ b/include/drm/drm_plane.h @@ -842,6 +842,26 @@ int drm_mode_plane_set_obj_prop(struct drm_plane *plane, struct drm_property *property, uint64_t value); +/** + * __drm_plane_find - find a &drm_plane + * @dev: DRM device + * @file_priv: drm file to check for lease against. + * @id: plane id + * + * Returns the plane with @id, NULL if it doesn't exist. + * + * Similar to drm_plane_find(), but called with &drm_device.master_rwsem held. + */ +static inline struct drm_plane *__drm_plane_find(struct drm_device *dev, + struct drm_file *file_priv, + uint32_t id) +{ + struct drm_mode_object *mo; + + mo = __drm_mode_object_find(dev, file_priv, id, DRM_MODE_OBJECT_PLANE); + return mo ? obj_to_plane(mo) : NULL; +} + /** * drm_plane_find - find a &drm_plane * @dev: DRM device
__drm_mode_object_find checks if the given drm file holds the required lease on a object by calling _drm_lease_held. _drm_lease_held in turn uses drm_file_get_master to access drm_file.master. However, in a future patch, the drm_file.master_lookup_lock in drm_file_get_master will be replaced by drm_device.master_rwsem. This is an issue for two reasons: 1. master_rwsem is sometimes already held when __drm_mode_object_find is called, which leads to recursive locks on master_rwsem 2. drm_mode_object_find is sometimes called with the modeset_mutex held, which leads to an inversion of the master_rwsem --> modeset_mutex lock hierarchy To fix this, we make __drm_mode_object_find the locked version of drm_mode_object_find, and wrap calls to __drm_mode_object_find with locks on master_rwsem. This allows us to safely access drm_file.master in _drm_lease_held (__drm_mode_object_find is its only caller) without the use of drm_file_get_master. Functions that already lock master_rwsem are modified to call __drm_mode_object_find, whereas functions that haven't locked master_rwsem should call drm_mode_object_find. These two options allow us to grab master_rwsem before modeset_mutex (such as in drm_mode_get_obj_get_properties_ioctl). This new rule requires more extensive changes to three functions: drn_connector_lookup, drm_crtc_find, and drm_plane_find. These functions are only sometimes called with master_rwsem held. Hence, we have to further split them into locked and unlocked versions that call __drm_mode_object_find and drm_mode_object_find respectively. Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com> --- drivers/gpu/drm/drm_atomic_uapi.c | 7 ++--- drivers/gpu/drm/drm_color_mgmt.c | 2 +- drivers/gpu/drm/drm_crtc.c | 5 ++-- drivers/gpu/drm/drm_framebuffer.c | 2 +- drivers/gpu/drm/drm_lease.c | 21 +++++---------- drivers/gpu/drm/drm_mode_object.c | 28 +++++++++++++++++--- drivers/gpu/drm/drm_plane.c | 8 +++--- drivers/gpu/drm/drm_property.c | 6 ++--- drivers/gpu/drm/i915/display/intel_overlay.c | 2 +- drivers/gpu/drm/i915/display/intel_sprite.c | 2 +- drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 2 +- include/drm/drm_connector.h | 23 ++++++++++++++++ include/drm/drm_crtc.h | 22 +++++++++++++++ include/drm/drm_mode_object.h | 3 +++ include/drm/drm_plane.h | 20 ++++++++++++++ 15 files changed, 118 insertions(+), 35 deletions(-)