[PATCH 1/4] drm/ttm: add a pointer to the allocating BO into ttm_resource
Thomas Hellström (Intel)
thomas_os at shipmail.org
Fri Jun 11 05:34:04 UTC 2021
Hi, Christian,
I know you have a lot on your plate, and that the drm community is a bit
lax about following the kernel patch submitting guidelines, but now that
we're also spinning up a number of Intel developers on TTM could we
please make a better effort with cover letters and commit messages so
that they understand what the purpose and end goal of the series is. A
reviewer shouldn't have to look at the last patch to try to get an
understanding what the series is doing and why.
On 6/10/21 1:05 PM, Christian König wrote:
> We are going to need this for the next patch
> and it allows us to clean
> up amdgpu as well.
The amdgpu changes are not reflected in the commit title.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c | 47 ++++++++-------------
> drivers/gpu/drm/ttm/ttm_resource.c | 1 +
> include/drm/ttm/ttm_resource.h | 1 +
> 3 files changed, 19 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> index 194f9eecf89c..8e3f5da44e4f 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> @@ -26,23 +26,12 @@
>
> #include "amdgpu.h"
>
> -struct amdgpu_gtt_node {
> - struct ttm_buffer_object *tbo;
> - struct ttm_range_mgr_node base;
> -};
> -
> static inline struct amdgpu_gtt_mgr *
> to_gtt_mgr(struct ttm_resource_manager *man)
> {
> return container_of(man, struct amdgpu_gtt_mgr, manager);
> }
>
> -static inline struct amdgpu_gtt_node *
> -to_amdgpu_gtt_node(struct ttm_resource *res)
> -{
> - return container_of(res, struct amdgpu_gtt_node, base.base);
> -}
> -
> /**
> * DOC: mem_info_gtt_total
> *
> @@ -107,9 +96,9 @@ const struct attribute_group amdgpu_gtt_mgr_attr_group = {
> */
> bool amdgpu_gtt_mgr_has_gart_addr(struct ttm_resource *res)
> {
> - struct amdgpu_gtt_node *node = to_amdgpu_gtt_node(res);
> + struct ttm_range_mgr_node *node = to_ttm_range_mgr_node(res);
>
> - return drm_mm_node_allocated(&node->base.mm_nodes[0]);
> + return drm_mm_node_allocated(&node->mm_nodes[0]);
> }
>
> /**
> @@ -129,7 +118,7 @@ static int amdgpu_gtt_mgr_new(struct ttm_resource_manager *man,
> {
> struct amdgpu_gtt_mgr *mgr = to_gtt_mgr(man);
> uint32_t num_pages = PFN_UP(tbo->base.size);
> - struct amdgpu_gtt_node *node;
> + struct ttm_range_mgr_node *node;
> int r;
>
> spin_lock(&mgr->lock);
> @@ -141,19 +130,17 @@ static int amdgpu_gtt_mgr_new(struct ttm_resource_manager *man,
> atomic64_sub(num_pages, &mgr->available);
> spin_unlock(&mgr->lock);
>
> - node = kzalloc(struct_size(node, base.mm_nodes, 1), GFP_KERNEL);
> + node = kzalloc(struct_size(node, mm_nodes, 1), GFP_KERNEL);
> if (!node) {
> r = -ENOMEM;
> goto err_out;
> }
>
> - node->tbo = tbo;
> - ttm_resource_init(tbo, place, &node->base.base);
> -
> + ttm_resource_init(tbo, place, &node->base);
> if (place->lpfn) {
> spin_lock(&mgr->lock);
> r = drm_mm_insert_node_in_range(&mgr->mm,
> - &node->base.mm_nodes[0],
> + &node->mm_nodes[0],
> num_pages, tbo->page_alignment,
> 0, place->fpfn, place->lpfn,
> DRM_MM_INSERT_BEST);
> @@ -161,14 +148,14 @@ static int amdgpu_gtt_mgr_new(struct ttm_resource_manager *man,
> if (unlikely(r))
> goto err_free;
>
> - node->base.base.start = node->base.mm_nodes[0].start;
> + node->base.start = node->mm_nodes[0].start;
> } else {
> - node->base.mm_nodes[0].start = 0;
> - node->base.mm_nodes[0].size = node->base.base.num_pages;
> - node->base.base.start = AMDGPU_BO_INVALID_OFFSET;
> + node->mm_nodes[0].start = 0;
> + node->mm_nodes[0].size = node->base.num_pages;
> + node->base.start = AMDGPU_BO_INVALID_OFFSET;
> }
>
> - *res = &node->base.base;
> + *res = &node->base;
> return 0;
>
> err_free:
> @@ -191,12 +178,12 @@ static int amdgpu_gtt_mgr_new(struct ttm_resource_manager *man,
> static void amdgpu_gtt_mgr_del(struct ttm_resource_manager *man,
> struct ttm_resource *res)
> {
> - struct amdgpu_gtt_node *node = to_amdgpu_gtt_node(res);
> + struct ttm_range_mgr_node *node = to_ttm_range_mgr_node(res);
> struct amdgpu_gtt_mgr *mgr = to_gtt_mgr(man);
>
> spin_lock(&mgr->lock);
> - if (drm_mm_node_allocated(&node->base.mm_nodes[0]))
> - drm_mm_remove_node(&node->base.mm_nodes[0]);
> + if (drm_mm_node_allocated(&node->mm_nodes[0]))
> + drm_mm_remove_node(&node->mm_nodes[0]);
> spin_unlock(&mgr->lock);
> atomic64_add(res->num_pages, &mgr->available);
>
> @@ -228,14 +215,14 @@ uint64_t amdgpu_gtt_mgr_usage(struct ttm_resource_manager *man)
> int amdgpu_gtt_mgr_recover(struct ttm_resource_manager *man)
> {
> struct amdgpu_gtt_mgr *mgr = to_gtt_mgr(man);
> - struct amdgpu_gtt_node *node;
> + struct ttm_range_mgr_node *node;
> struct drm_mm_node *mm_node;
> int r = 0;
>
> spin_lock(&mgr->lock);
> drm_mm_for_each_node(mm_node, &mgr->mm) {
> - node = container_of(mm_node, typeof(*node), base.mm_nodes[0]);
> - r = amdgpu_ttm_recover_gart(node->tbo);
> + node = container_of(mm_node, typeof(*node), mm_nodes[0]);
> + r = amdgpu_ttm_recover_gart(node->base.bo);
> if (r)
> break;
> }
> diff --git a/drivers/gpu/drm/ttm/ttm_resource.c b/drivers/gpu/drm/ttm/ttm_resource.c
> index 2431717376e7..7ff6194154fe 100644
> --- a/drivers/gpu/drm/ttm/ttm_resource.c
> +++ b/drivers/gpu/drm/ttm/ttm_resource.c
> @@ -41,6 +41,7 @@ void ttm_resource_init(struct ttm_buffer_object *bo,
> res->bus.offset = 0;
> res->bus.is_iomem = false;
> res->bus.caching = ttm_cached;
> + res->bo = bo;
> }
> EXPORT_SYMBOL(ttm_resource_init);
>
> diff --git a/include/drm/ttm/ttm_resource.h b/include/drm/ttm/ttm_resource.h
> index 140b6b9a8bbe..6d0b7a6d2169 100644
> --- a/include/drm/ttm/ttm_resource.h
> +++ b/include/drm/ttm/ttm_resource.h
> @@ -171,6 +171,7 @@ struct ttm_resource {
> uint32_t mem_type;
> uint32_t placement;
> struct ttm_bus_placement bus;
> + struct ttm_buffer_object *bo;
Not that I'm against this change by itself, but this bo pointer is not
refcounted, and therefore needs a description when it's needed and why.
What happens, for example when the resource is moved to a ghost object,
or the bo is killed while the resource is remaining on a lru list (which
I understand was one of the main purposes with free-standing resources).
Weak references need a guarantee that the object they pointed to is
alive. What is that guarantee?
Also could we introduce new TTM structure members where they are first
used /referenced by TTM and not where they are used by amdgpu? Without
finding out in patch 3 that this member is needed to look up the bo from
a lru list the correct response to this patch would have been: That bo
is amdgpu-specific and needs to be in a driver private struct...
Thanks,
/Thomas
> };
>
> /**
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