[Intel-gfx] [PATCH 1/3] drm: Update GEM refcounting docs
Alex Deucher
alexdeucher at gmail.com
Thu Oct 22 10:54:17 PDT 2015
On Thu, Oct 22, 2015 at 1:11 PM, Daniel Vetter <daniel.vetter at 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 at intel.com>
Patches 1 and 3 are:
Reviewed-by: Alex Deucher <alexander.deucher at 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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