On Tue, Dec 2, 2014 at 1:47 PM, Sean Paul <seanpaul@xxxxxxxxxxxx> wrote:
> On Wed, Nov 26, 2014 at 4:19 PM, Rob Clark <robdclark@xxxxxxxxx> wrote:
>> Keep property pointer, instead of id, in per mode-object attachments.
>> This will simplify things in later patches.
>>
>> ---
>> Does anyone care about the lifetime issue and dangling property ptrs?
>
> Judging by the lack of response, it seems like the answer is probably no.
>
> That said, it doesn't seem like a whole lot of work to add refcounting
> to drm_property so we don't have to worry about it. Maybe I'm missing
> something.
true.. but then the property would not actually go away then, it would
be kept alive by the extra ref. That said, I can't think of a valid
reason for dynamically creating/destroying properties, so I'm tempted
to just add a comment somewhere to explain that detaching from mode
objects would be required if someone did want to dynamically destroy a
property and leave it at that..
BR,
-R
> Sean
>
>
>> Currently properties are destroyed during drm_mode_config_cleanup(),
>> so it doesn't really matter.. if someone *did* see a use for dynamically
>> destroying properties we'd have to do something a bit more clever and
>> handle properly detaching from any mode object to which that property
>> had been attached.
>>
>> Just sending as an RFC for now, but later atomic properties/ioctl patches
>> will depend on this.
>>
>> drivers/gpu/drm/drm_crtc.c | 17 ++++++++---------
>> include/drm/drm_crtc.h | 7 ++++++-
>> 2 files changed, 14 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
>> index 3ba84df..3e6ef39 100644
>> --- a/drivers/gpu/drm/drm_crtc.c
>> +++ b/drivers/gpu/drm/drm_crtc.c
>> @@ -2058,12 +2058,11 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
>> prop_ptr = (uint32_t __user *)(unsigned long)(out_resp->props_ptr);
>> prop_values = (uint64_t __user *)(unsigned long)(out_resp->prop_values_ptr);
>> for (i = 0; i < connector->properties.count; i++) {
>> - if (put_user(connector->properties.ids[i],
>> - prop_ptr + copied)) {
>> + struct drm_property *prop = connector->properties.properties[i];
>> + if (put_user(prop->base.id, prop_ptr + copied)) {
>> ret = -EFAULT;
>> goto out;
>> }
>> -
>> if (put_user(connector->properties.values[i],
>> prop_values + copied)) {
>> ret = -EFAULT;
>> @@ -3744,7 +3743,7 @@ void drm_object_attach_property(struct drm_mode_object *obj,
>> return;
>> }
>>
>> - obj->properties->ids[count] = property->base.id;
>> + obj->properties->properties[count] = property;
>> obj->properties->values[count] = init_val;
>> obj->properties->count++;
>> }
>> @@ -3769,7 +3768,7 @@ int drm_object_property_set_value(struct drm_mode_object *obj,
>> int i;
>>
>> for (i = 0; i < obj->properties->count; i++) {
>> - if (obj->properties->ids[i] == property->base.id) {
>> + if (obj->properties->properties[i] == property) {
>> obj->properties->values[i] = val;
>> return 0;
>> }
>> @@ -3799,7 +3798,7 @@ int drm_object_property_get_value(struct drm_mode_object *obj,
>> int i;
>>
>> for (i = 0; i < obj->properties->count; i++) {
>> - if (obj->properties->ids[i] == property->base.id) {
>> + if (obj->properties->properties[i] == property) {
>> *val = obj->properties->values[i];
>> return 0;
>> }
>> @@ -4263,8 +4262,8 @@ int drm_mode_obj_get_properties_ioctl(struct drm_device *dev, void *data,
>> prop_values_ptr = (uint64_t __user *)(unsigned long)
>> (arg->prop_values_ptr);
>> for (i = 0; i < props_count; i++) {
>> - if (put_user(obj->properties->ids[i],
>> - props_ptr + copied)) {
>> + struct drm_property *prop = obj->properties->properties[i];
>> + if (put_user(prop->base.id, props_ptr + copied)) {
>> ret = -EFAULT;
>> goto out;
>> }
>> @@ -4322,7 +4321,7 @@ int drm_mode_obj_set_property_ioctl(struct drm_device *dev, void *data,
>> goto out;
>>
>> for (i = 0; i < arg_obj->properties->count; i++)
>> - if (arg_obj->properties->ids[i] == arg->prop_id)
>> + if (arg_obj->properties->properties[i]->base.id == arg->prop_id)
>> break;
>>
>> if (i == arg_obj->properties->count)
>> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
>> index dd2c16e..017029d 100644
>> --- a/include/drm/drm_crtc.h
>> +++ b/include/drm/drm_crtc.h
>> @@ -64,7 +64,12 @@ struct drm_mode_object {
>> #define DRM_OBJECT_MAX_PROPERTY 24
>> struct drm_object_properties {
>> int count;
>> - uint32_t ids[DRM_OBJECT_MAX_PROPERTY];
>> + /* NOTE: if we ever start dynamically destroying properties (ie.
>> + * not at drm_mode_config_cleanup() time), then we'd have to do
>> + * a better job of detaching property from mode objects to avoid
>> + * dangling property pointers:
>> + */
>> + struct drm_property *properties[DRM_OBJECT_MAX_PROPERTY];
>> uint64_t values[DRM_OBJECT_MAX_PROPERTY];
>> };
>>
>> --
>> 1.9.3
>>
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