Re: [PATCH 1/2] drm/ttm: cleanup ttm_mem_type_manager_func.get_node interface

[Christian König <ckoenig.leichtzumerken@xxxxxxxxx>]

Am 26.06.20 um 19:39 schrieb Ruhl, Michael J:
> > -----Original Message-----
> > From: dri-devel <dri-devel-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of
> > Christian König
> > Sent: Wednesday, June 24, 2020 9:36 AM
> > To: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > Subject: [PATCH 1/2] drm/ttm: cleanup
> > ttm_mem_type_manager_func.get_node interface
> >
> > Instead of signaling failure by setting the node pointer to
> > NULL do so by returning -ENOSPC.
> >
> > Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> > ---
> > drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c   |  4 +---
> > drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c  |  5 ++---
> > drivers/gpu/drm/nouveau/nouveau_ttm.c         |  8 --------
> > drivers/gpu/drm/ttm/ttm_bo.c                  | 11 +++++------
> > drivers/gpu/drm/ttm/ttm_bo_manager.c          |  2 +-
> > drivers/gpu/drm/vmwgfx/vmwgfx_gmrid_manager.c |  4 +---
> > 6 files changed, 10 insertions(+), 24 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> > index 627104401e84..2baa80224fa4 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
> > @@ -229,7 +229,7 @@ static int amdgpu_gtt_mgr_new(struct
> > ttm_mem_type_manager *man,
> > 	if ((&tbo->mem == mem || tbo->mem.mem_type != TTM_PL_TT) &&
> > 	    atomic64_read(&mgr->available) < mem->num_pages) {
> > 		spin_unlock(&mgr->lock);
> > -		return 0;
> > +		return -ENOSPC;
> > 	}
> > 	atomic64_sub(mem->num_pages, &mgr->available);
> > 	spin_unlock(&mgr->lock);
> > @@ -249,8 +249,6 @@ static int amdgpu_gtt_mgr_new(struct
> > ttm_mem_type_manager *man,
> > 		r = amdgpu_gtt_mgr_alloc(man, tbo, place, mem);
> > 		if (unlikely(r)) {
> > 			kfree(node);
> > -			mem->mm_node = NULL;
> Hmm, amdgpu_gtt_mgr_del() grabs mem->mm_node and kfrees it.
>
> If this value is not NUL, it looks like bad things could happen.
>
> Will _mgr_del never get called in this case?

Yes, everything else would be a bug.

> Using the return value seems pretty reasonable, leaving bad pointers
> lying around makes me slightly nervous.

The caller should not touch the member when an error occurred since it 
is certainly not initialized.

But it might be a good idea to zero initialize the structure by the 
caller just to be sure.

Thanks for the comment,
Christian.

> Mike
>
> > -			r = 0;
> > 			goto err_out;
> > 		}
> > 	} else {
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> > index 128a667ed8fa..e8d1dd564006 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> > @@ -336,8 +336,7 @@ static int amdgpu_vram_mgr_new(struct
> > ttm_mem_type_manager *man,
> > 	mem_bytes = (u64)mem->num_pages << PAGE_SHIFT;
> > 	if (atomic64_add_return(mem_bytes, &mgr->usage) > max_bytes) {
> > 		atomic64_sub(mem_bytes, &mgr->usage);
> > -		mem->mm_node = NULL;
> > -		return 0;
> > +		return -ENOSPC;
> > 	}
> >
> > 	if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
> > @@ -417,7 +416,7 @@ static int amdgpu_vram_mgr_new(struct
> > ttm_mem_type_manager *man,
> > 	atomic64_sub(mem->num_pages << PAGE_SHIFT, &mgr->usage);
> >
> > 	kvfree(nodes);
> > -	return r == -ENOSPC ? 0 : r;
> > +	return r;
> > }
> >
> > /**
> > diff --git a/drivers/gpu/drm/nouveau/nouveau_ttm.c
> > b/drivers/gpu/drm/nouveau/nouveau_ttm.c
> > index 7ca0a2498532..e89ea052cf71 100644
> > --- a/drivers/gpu/drm/nouveau/nouveau_ttm.c
> > +++ b/drivers/gpu/drm/nouveau/nouveau_ttm.c
> > @@ -75,10 +75,6 @@ nouveau_vram_manager_new(struct
> > ttm_mem_type_manager *man,
> > 	ret = nouveau_mem_vram(reg, nvbo->contig, nvbo->page);
> > 	if (ret) {
> > 		nouveau_mem_del(reg);
> > -		if (ret == -ENOSPC) {
> > -			reg->mm_node = NULL;
> > -			return 0;
> > -		}
> > 		return ret;
> > 	}
> >
> > @@ -139,10 +135,6 @@ nv04_gart_manager_new(struct
> > ttm_mem_type_manager *man,
> > 			   reg->num_pages << PAGE_SHIFT, &mem->vma[0]);
> > 	if (ret) {
> > 		nouveau_mem_del(reg);
> > -		if (ret == -ENOSPC) {
> > -			reg->mm_node = NULL;
> > -			return 0;
> > -		}
> > 		return ret;
> > 	}
> >
> > diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> > index f73b81c2576e..15f9b19fa00d 100644
> > --- a/drivers/gpu/drm/ttm/ttm_bo.c
> > +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> > @@ -916,10 +916,10 @@ static int ttm_bo_mem_force_space(struct
> > ttm_buffer_object *bo,
> > 	ticket = dma_resv_locking_ctx(bo->base.resv);
> > 	do {
> > 		ret = (*man->func->get_node)(man, bo, place, mem);
> > -		if (unlikely(ret != 0))
> > -			return ret;
> > -		if (mem->mm_node)
> > +		if (likely(!ret))
> > 			break;
> > +		if (unlikely(ret != -ENOSPC))
> > +			return ret;
> > 		ret = ttm_mem_evict_first(bdev, mem->mem_type, place,
> > ctx,
> > 					  ticket);
> > 		if (unlikely(ret != 0))
> > @@ -1063,12 +1063,11 @@ int ttm_bo_mem_space(struct ttm_buffer_object
> > *bo,
> >
> > 		man = &bdev->man[mem->mem_type];
> > 		ret = (*man->func->get_node)(man, bo, place, mem);
> > +		if (ret == -ENOSPC)
> > +			continue;
> > 		if (unlikely(ret))
> > 			goto error;
> >
> > -		if (!mem->mm_node)
> > -			continue;
> > -
> > 		ret = ttm_bo_add_move_fence(bo, man, mem, ctx-
> > > no_wait_gpu);
> > 		if (unlikely(ret)) {
> > 			(*man->func->put_node)(man, mem);
> > diff --git a/drivers/gpu/drm/ttm/ttm_bo_manager.c
> > b/drivers/gpu/drm/ttm/ttm_bo_manager.c
> > index 18d3debcc949..facd3049c3aa 100644
> > --- a/drivers/gpu/drm/ttm/ttm_bo_manager.c
> > +++ b/drivers/gpu/drm/ttm/ttm_bo_manager.c
> > @@ -86,7 +86,7 @@ static int ttm_bo_man_get_node(struct
> > ttm_mem_type_manager *man,
> > 		mem->start = node->start;
> > 	}
> >
> > -	return 0;
> > +	return ret;
> > }
> >
> > static void ttm_bo_man_put_node(struct ttm_mem_type_manager *man,
> > diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_gmrid_manager.c
> > b/drivers/gpu/drm/vmwgfx/vmwgfx_gmrid_manager.c
> > index 7da752ca1c34..4a76fc7114ad 100644
> > --- a/drivers/gpu/drm/vmwgfx/vmwgfx_gmrid_manager.c
> > +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_gmrid_manager.c
> > @@ -53,8 +53,6 @@ static int vmw_gmrid_man_get_node(struct
> > ttm_mem_type_manager *man,
> > 		(struct vmwgfx_gmrid_man *)man->priv;
> > 	int id;
> >
> > -	mem->mm_node = NULL;
> > -
> > 	id = ida_alloc_max(&gman->gmr_ida, gman->max_gmr_ids - 1,
> > GFP_KERNEL);
> > 	if (id < 0)
> > 		return (id != -ENOMEM ? 0 : id);
> > @@ -78,7 +76,7 @@ static int vmw_gmrid_man_get_node(struct
> > ttm_mem_type_manager *man,
> > 	gman->used_gmr_pages -= bo->num_pages;
> > 	spin_unlock(&gman->lock);
> > 	ida_free(&gman->gmr_ida, id);
> > -	return 0;
> > +	return -ENOSPC;
> > }
> >
> > static void vmw_gmrid_man_put_node(struct ttm_mem_type_manager
> > *man,
> > --
> > 2.17.1
> >
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel

_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/dri-devel