Re: [PATCH 06/11] drm/syncobj: add timeline payload query ioctl v4

["Koenig, Christian" <Christian.Koenig-5C7GfCeVMHo@public.gmane.org>]

Am 18.02.19 um 04:10 schrieb zhoucm1:
>
>
> On 2019年02月17日 03:22, Christian König wrote:
>> Am 15.02.19 um 20:31 schrieb Lionel Landwerlin via amd-gfx:
>>> On 07/12/2018 09:55, Chunming Zhou wrote:
>>>> user mode can query timeline payload.
>>>> v2: check return value of copy_to_user
>>>> v3: handle querying entry by entry
>>>> v4: rebase on new chain container, simplify interface
>>>>
>>>> Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
>>>> Cc: Daniel Rakos <Daniel.Rakos@amd.com>
>>>> Cc: Jason Ekstrand <jason@jlekstrand.net>
>>>> Cc: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
>>>> Cc: Dave Airlie <airlied@redhat.com>
>>>> Cc: Christian König <christian.koenig@amd.com>
>>>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>>>> ---
>>>>   drivers/gpu/drm/drm_internal.h |  2 ++
>>>>   drivers/gpu/drm/drm_ioctl.c    |  2 ++
>>>>   drivers/gpu/drm/drm_syncobj.c  | 43 
>>>> ++++++++++++++++++++++++++++++++++
>>>>   include/uapi/drm/drm.h         | 10 ++++++++
>>>>   4 files changed, 57 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/drm_internal.h 
>>>> b/drivers/gpu/drm/drm_internal.h
>>>> index 18b41e10195c..dab4d5936441 100644
>>>> --- a/drivers/gpu/drm/drm_internal.h
>>>> +++ b/drivers/gpu/drm/drm_internal.h
>>>> @@ -184,6 +184,8 @@ int drm_syncobj_reset_ioctl(struct drm_device 
>>>> *dev, void *data,
>>>>                   struct drm_file *file_private);
>>>>   int drm_syncobj_signal_ioctl(struct drm_device *dev, void *data,
>>>>                    struct drm_file *file_private);
>>>> +int drm_syncobj_query_ioctl(struct drm_device *dev, void *data,
>>>> +                struct drm_file *file_private);
>>>>     /* drm_framebuffer.c */
>>>>   void drm_framebuffer_print_info(struct drm_printer *p, unsigned 
>>>> int indent,
>>>> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
>>>> index a9a17ed35cc4..7578ef6dc1d1 100644
>>>> --- a/drivers/gpu/drm/drm_ioctl.c
>>>> +++ b/drivers/gpu/drm/drm_ioctl.c
>>>> @@ -681,6 +681,8 @@ static const struct drm_ioctl_desc drm_ioctls[] 
>>>> = {
>>>>                 DRM_UNLOCKED|DRM_RENDER_ALLOW),
>>>>       DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_SIGNAL, 
>>>> drm_syncobj_signal_ioctl,
>>>>                 DRM_UNLOCKED|DRM_RENDER_ALLOW),
>>>> +    DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_QUERY, drm_syncobj_query_ioctl,
>>>> +              DRM_UNLOCKED|DRM_RENDER_ALLOW),
>>>>       DRM_IOCTL_DEF(DRM_IOCTL_CRTC_GET_SEQUENCE, 
>>>> drm_crtc_get_sequence_ioctl, DRM_UNLOCKED),
>>>>       DRM_IOCTL_DEF(DRM_IOCTL_CRTC_QUEUE_SEQUENCE, 
>>>> drm_crtc_queue_sequence_ioctl, DRM_UNLOCKED),
>>>>       DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATE_LEASE, 
>>>> drm_mode_create_lease_ioctl, DRM_MASTER|DRM_UNLOCKED),
>>>> diff --git a/drivers/gpu/drm/drm_syncobj.c 
>>>> b/drivers/gpu/drm/drm_syncobj.c
>>>> index 348079bb0965..f97fa00ca1d0 100644
>>>> --- a/drivers/gpu/drm/drm_syncobj.c
>>>> +++ b/drivers/gpu/drm/drm_syncobj.c
>>>> @@ -1061,3 +1061,46 @@ drm_syncobj_signal_ioctl(struct drm_device 
>>>> *dev, void *data,
>>>>         return ret;
>>>>   }
>>>> +
>>>> +int drm_syncobj_query_ioctl(struct drm_device *dev, void *data,
>>>> +                struct drm_file *file_private)
>>>> +{
>>>> +    struct drm_syncobj_timeline_array *args = data;
>>>> +    struct drm_syncobj **syncobjs;
>>>> +    uint64_t __user *points = u64_to_user_ptr(args->points);
>>>> +    uint32_t i;
>>>> +    int ret;
>>>> +
>>>> +    if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))
>>>> +        return -ENODEV;
>>>> +
>>>> +    if (args->pad != 0)
>>>> +        return -EINVAL;
>>>> +
>>>> +    if (args->count_handles == 0)
>>>> +        return -EINVAL;
>>>> +
>>>> +    ret = drm_syncobj_array_find(file_private,
>>>> +                     u64_to_user_ptr(args->handles),
>>>> +                     args->count_handles,
>>>> +                     &syncobjs);
>>>> +    if (ret < 0)
>>>> +        return ret;
>>>> +
>>>> +    for (i = 0; i < args->count_handles; i++) {
>>>> +        struct dma_fence_chain *chain;
>>>> +        struct dma_fence *fence;
>>>> +        uint64_t point;
>>>> +
>>>> +        fence = drm_syncobj_fence_get(syncobjs[i]);
>>>> +        chain = to_dma_fence_chain(fence);
>>>> +        point = chain ? fence->seqno : 0;
>>>
>>>
>>> Sorry, I don' t want to sound annoying, but this looks like this 
>>> could report values going backward.
>>
>> Well please be annoying as much as you can :) But yeah all that stuff 
>> has been discussed before as well.
>>
>>>
>>> Anything add a point X to a timeline that has reached value Y with X 
>>> < Y would trigger that.
>>
>> Yes, that can indeed happen.
> trigger what? when adding x (x < y), then return 0 when query?
> Why would this happen?
> No, syncobj->fence should always be there and the last chain node, if 
> it is ever added.

Well maybe Lionel should clarify a bit what he means?

I thought he is concerned that the call could return values where X < Y, 
but that doesn't seem to be the case.

Christian.

>
> -David
>> But adding a timeline point X which is before the already added point 
>> Y is illegal in the first place :)
>>
>> So when the application does something stupid and breaks it can just 
>> keep the pieces.
>>
>> In the kernel we still do the most defensive thing and sync to 
>> everything in this case.
>>
>> I'm just not sure if we should print an error into syslog or just 
>> continue silently.
>>
>> Regards,
>> Christian.
>>
>>>
>>> Either through the submission or userspace signaling or importing 
>>> another syncpoint's fence.
>>>
>>>
>>> -Lionel
>>>
>>>
>>>> +        ret = copy_to_user(&points[i], &point, sizeof(uint64_t));
>>>> +        ret = ret ? -EFAULT : 0;
>>>> +        if (ret)
>>>> +            break;
>>>> +    }
>>>> +    drm_syncobj_array_free(syncobjs, args->count_handles);
>>>> +
>>>> +    return ret;
>>>> +}
>>>> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
>>>> index 0092111d002c..b2c36f2b2599 100644
>>>> --- a/include/uapi/drm/drm.h
>>>> +++ b/include/uapi/drm/drm.h
>>>> @@ -767,6 +767,14 @@ struct drm_syncobj_array {
>>>>       __u32 pad;
>>>>   };
>>>>   +struct drm_syncobj_timeline_array {
>>>> +    __u64 handles;
>>>> +    __u64 points;
>>>> +    __u32 count_handles;
>>>> +    __u32 pad;
>>>> +};
>>>> +
>>>> +
>>>>   /* Query current scanout sequence number */
>>>>   struct drm_crtc_get_sequence {
>>>>       __u32 crtc_id;        /* requested crtc_id */
>>>> @@ -924,6 +932,8 @@ extern "C" {
>>>>   #define DRM_IOCTL_MODE_REVOKE_LEASE    DRM_IOWR(0xC9, struct 
>>>> drm_mode_revoke_lease)
>>>>     #define DRM_IOCTL_SYNCOBJ_TIMELINE_WAIT DRM_IOWR(0xCA, struct 
>>>> drm_syncobj_timeline_wait)
>>>> +#define DRM_IOCTL_SYNCOBJ_QUERY        DRM_IOWR(0xCB, struct 
>>>> drm_syncobj_timeline_array)
>>>> +
>>>>   /**
>>>>    * Device specific ioctls should only be in their respective headers
>>>>    * The device specific ioctl range is from 0x40 to 0x9f.
>>>
>>>
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>>> amd-gfx@lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
>>
>

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