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

[Lionel Landwerlin <lionel.g.landwerlin-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On 18/02/2019 07:28, Koenig, Christian wrote:
> 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.


I meant something like this :


t = create_timeline_syncobj()

signal(t, 2)

query(t) => 2

signal(t, 1)

query(t) => 1


-Lionel



>
>> -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
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