Re: [PATCH 1/3] drm: Update GEM refcounting docs

[Alex Deucher <alexdeucher@gmail.com>]

On Thu, Oct 22, 2015 at 1:11 PM, Daniel Vetter <daniel.vetter@ffwll.ch> wrote:
> I just realized that I've forgotten to update all the gem refcounting
> docs. For pennance also add pretty docs for the overall drm_gem_object
> structure, with a few links thrown in fore good.
>
> As usually we need to make sure the kerneldoc reference is at most a
> sect2 for otherwise it won't be listed.
>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

Patches 1 and 3 are:
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

> ---
>  Documentation/DocBook/gpu.tmpl |  15 +++---
>  include/drm/drm_gem.h          | 106 +++++++++++++++++++++++++++++++++++------
>  2 files changed, 100 insertions(+), 21 deletions(-)
>
> diff --git a/Documentation/DocBook/gpu.tmpl b/Documentation/DocBook/gpu.tmpl
> index 90c2aab31269..6c5865bb5ee8 100644
> --- a/Documentation/DocBook/gpu.tmpl
> +++ b/Documentation/DocBook/gpu.tmpl
> @@ -635,10 +635,10 @@ char *date;</synopsis>
>            acquired and release by <function>calling drm_gem_object_reference</function>
>            and <function>drm_gem_object_unreference</function> respectively. The
>            caller must hold the <structname>drm_device</structname>
> -          <structfield>struct_mutex</structfield> lock. As a convenience, GEM
> -          provides the <function>drm_gem_object_reference_unlocked</function> and
> -          <function>drm_gem_object_unreference_unlocked</function> functions that
> -          can be called without holding the lock.
> +         <structfield>struct_mutex</structfield> lock when calling
> +         <function>drm_gem_object_reference</function>. As a convenience, GEM
> +         provides <function>drm_gem_object_unreference_unlocked</function>
> +         functions that can be called without holding the lock.
>          </para>
>          <para>
>            When the last reference to a GEM object is released the GEM core calls
> @@ -836,10 +836,11 @@ char *date;</synopsis>
>            abstracted from the client in libdrm.
>          </para>
>        </sect3>
> -      <sect3>
> -        <title>GEM Function Reference</title>
> +    </sect2>
> +    <sect2>
> +      <title>GEM Function Reference</title>
>  !Edrivers/gpu/drm/drm_gem.c
> -      </sect3>
> +!Iinclude/drm/drm_gem.h
>      </sect2>
>      <sect2>
>        <title>VMA Offset Manager</title>
> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
> index 15e7f007380f..0b3e11ab8757 100644
> --- a/include/drm/drm_gem.h
> +++ b/include/drm/drm_gem.h
> @@ -35,76 +35,129 @@
>   */
>
>  /**
> - * This structure defines the drm_mm memory object, which will be used by the
> - * DRM for its buffer objects.
> + * struct drm_gem_object - GEM buffer object
> + *
> + * This structure defines the generic parts for GEM buffer objects, which are
> + * mostly around handling mmap and userspace handles.
> + *
> + * Buffer objects are often abbreviated to BO.
>   */
>  struct drm_gem_object {
> -       /** Reference count of this object */
> +       /**
> +        * @refcount:
> +        *
> +        * Reference count of this object
> +        *
> +        * Please use drm_gem_object_reference() to acquire and
> +        * drm_gem_object_unreference() or drm_gem_object_unreference_unlocked()
> +        * to release a reference to a GEM buffer object.
> +        */
>         struct kref refcount;
>
>         /**
> -        * handle_count - gem file_priv handle count of this object
> +        * @handle_count:
> +        *
> +        * This is the GEM file_priv handle count of this object.
>          *
>          * Each handle also holds a reference. Note that when the handle_count
>          * drops to 0 any global names (e.g. the id in the flink namespace) will
>          * be cleared.
>          *
>          * Protected by dev->object_name_lock.
> -        * */
> +        */
>         unsigned handle_count;
>
> -       /** Related drm device */
> +       /**
> +        * @dev: DRM dev this object belongs to.
> +        */
>         struct drm_device *dev;
>
> -       /** File representing the shmem storage */
> +       /**
> +        * @filp:
> +        *
> +        * SHMEM file node used as backing storage for swappable buffer objects.
> +        * GEM also supports driver private objects with driver-specific backing
> +        * storage (contiguous CMA memory, special reserved blocks). In this
> +        * case @filp is NULL.
> +        */
>         struct file *filp;
>
> -       /* Mapping info for this object */
> +       /**
> +        * @vma_node:
> +        *
> +        * Mapping info for this object to support mmap. Drivers are supposed to
> +        * allocate the mmap offset using drm_gem_create_mmap_offset(). The
> +        * offset itself can be retrieved using drm_vma_node_offset_addr().
> +        *
> +        * Memory mapping itself is handled by drm_gem_mmap(), which also checks
> +        * that userspace is allowed to access the object.
> +        */
>         struct drm_vma_offset_node vma_node;
>
>         /**
> +        * @size:
> +        *
>          * Size of the object, in bytes.  Immutable over the object's
>          * lifetime.
>          */
>         size_t size;
>
>         /**
> +        * @name:
> +        *
>          * Global name for this object, starts at 1. 0 means unnamed.
> -        * Access is covered by the object_name_lock in the related drm_device
> +        * Access is covered by dev->object_name_lock. This is used by the GEM_FLINK
> +        * and GEM_OPEN ioctls.
>          */
>         int name;
>
>         /**
> -        * Memory domains. These monitor which caches contain read/write data
> +        * @read_domains:
> +        *
> +        * Read memory domains. These monitor which caches contain read/write data
>          * related to the object. When transitioning from one set of domains
>          * to another, the driver is called to ensure that caches are suitably
> -        * flushed and invalidated
> +        * flushed and invalidated.
>          */
>         uint32_t read_domains;
> +
> +       /**
> +        * @write_domain: Corresponding unique write memory domain.
> +        */
>         uint32_t write_domain;
>
>         /**
> +        * @pending_read_domains:
> +        *
>          * While validating an exec operation, the
>          * new read/write domain values are computed here.
>          * They will be transferred to the above values
>          * at the point that any cache flushing occurs
>          */
>         uint32_t pending_read_domains;
> +
> +       /**
> +        * @pending_write_domain: Write domain similar to @pending_read_domains.
> +        */
>         uint32_t pending_write_domain;
>
>         /**
> -        * dma_buf - dma buf associated with this GEM object
> +        * @dma_buf:
> +        *
> +        * dma-buf associated with this GEM object.
>          *
>          * Pointer to the dma-buf associated with this gem object (either
>          * through importing or exporting). We break the resulting reference
>          * loop when the last gem handle for this object is released.
>          *
> -        * Protected by obj->object_name_lock
> +        * Protected by obj->object_name_lock.
>          */
>         struct dma_buf *dma_buf;
>
>         /**
> -        * import_attach - dma buf attachment backing this object
> +        * @import_attach:
> +        *
> +        * dma-buf attachment backing this object.
>          *
>          * Any foreign dma_buf imported as a gem object has this set to the
>          * attachment point for the device. This is invariant over the lifetime
> @@ -133,12 +186,30 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
>                      struct vm_area_struct *vma);
>  int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma);
>
> +/**
> + * drm_gem_object_reference - acquire a GEM BO reference
> + * @obj: GEM buffer object
> + *
> + * This acquires additional reference to @obj. It is illegal to call this
> + * without already holding a reference. No locks required.
> + */
>  static inline void
>  drm_gem_object_reference(struct drm_gem_object *obj)
>  {
>         kref_get(&obj->refcount);
>  }
>
> +/**
> + * drm_gem_object_unreference - release a GEM BO reference
> + * @obj: GEM buffer object
> + *
> + * This releases a reference to @obj. Callers must hold the dev->struct_mutex
> + * lock when calling this function, even when the driver doesn't use
> + * dev->struct_mutex for anything.
> + *
> + * For drivers not encumbered with legacy locking use
> + * drm_gem_object_unreference_unlocked() instead.
> + */
>  static inline void
>  drm_gem_object_unreference(struct drm_gem_object *obj)
>  {
> @@ -149,6 +220,13 @@ drm_gem_object_unreference(struct drm_gem_object *obj)
>         }
>  }
>
> +/**
> + * drm_gem_object_unreference_unlocked - release a GEM BO reference
> + * @obj: GEM buffer object
> + *
> + * This releases a reference to @obj. Callers must not hold the
> + * dev->struct_mutex lock when calling this function.
> + */
>  static inline void
>  drm_gem_object_unreference_unlocked(struct drm_gem_object *obj)
>  {
> --
> 2.5.1
>
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