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

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

[Christian König]

Instead of signaling failure by setting the node pointer to
NULL do so by returning -ENOSPC.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 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;
-			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

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[PATCH 2/2] drm/ttm: make TT creation purely optional

[Christian König]

We only need the page array when the BO is about to be accessed.

So not only populate, but also create it on demand.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c      | 26 ++++----------------------
 drivers/gpu/drm/ttm/ttm_bo_util.c |  9 +++++++--
 drivers/gpu/drm/ttm/ttm_bo_vm.c   |  5 +++++
 3 files changed, 16 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 15f9b19fa00d..0e0a9dadf3ed 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -667,13 +667,8 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo,
 	placement.num_busy_placement = 0;
 	bdev->driver->evict_flags(bo, &placement);
 
-	if (!placement.num_placement && !placement.num_busy_placement) {
-		ret = ttm_bo_pipeline_gutting(bo);
-		if (ret)
-			return ret;
-
-		return ttm_tt_create(bo, false);
-	}
+	if (!placement.num_placement && !placement.num_busy_placement)
+		return ttm_bo_pipeline_gutting(bo);
 
 	evict_mem = bo->mem;
 	evict_mem.mm_node = NULL;
@@ -1200,13 +1195,8 @@ int ttm_bo_validate(struct ttm_buffer_object *bo,
 	/*
 	 * Remove the backing store if no placement is given.
 	 */
-	if (!placement->num_placement && !placement->num_busy_placement) {
-		ret = ttm_bo_pipeline_gutting(bo);
-		if (ret)
-			return ret;
-
-		return ttm_tt_create(bo, false);
-	}
+	if (!placement->num_placement && !placement->num_busy_placement)
+		return ttm_bo_pipeline_gutting(bo);
 
 	/*
 	 * Check whether we need to move buffer.
@@ -1223,14 +1213,6 @@ int ttm_bo_validate(struct ttm_buffer_object *bo,
 		ttm_flag_masked(&bo->mem.placement, new_flags,
 				~TTM_PL_MASK_MEMTYPE);
 	}
-	/*
-	 * We might need to add a TTM.
-	 */
-	if (bo->mem.mem_type == TTM_PL_SYSTEM && bo->ttm == NULL) {
-		ret = ttm_tt_create(bo, true);
-		if (ret)
-			return ret;
-	}
 	return 0;
 }
 EXPORT_SYMBOL(ttm_bo_validate);
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index 52d2b71f1588..f8414f820350 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -580,12 +580,17 @@ static int ttm_bo_kmap_ttm(struct ttm_buffer_object *bo,
 		.interruptible = false,
 		.no_wait_gpu = false
 	};
-	struct ttm_tt *ttm = bo->ttm;
+	struct ttm_tt *ttm;
 	pgprot_t prot;
 	int ret;
 
-	BUG_ON(!ttm);
+	if (!bo->ttm) {
+		ret = ttm_tt_create(bo, true);
+		if (ret)
+			return ret;
+	}
 
+	ttm = bo->ttm;
 	ret = ttm_tt_populate(ttm, &ctx);
 	if (ret)
 		return ret;
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 0ad30b112982..bdfed6725d6f 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -349,6 +349,11 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
 
 		};
 
+		if (!bo->ttm && ttm_tt_create(bo, true)) {
+			ret = VM_FAULT_OOM;
+			goto out_io_unlock;
+		}
+
 		ttm = bo->ttm;
 		if (ttm_tt_populate(bo->ttm, &ctx)) {
 			ret = VM_FAULT_OOM;
-- 
2.17.1

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

[Ruhl, Michael J]

>-----Original Message-----
>From: dri-devel <dri-devel-bounces@lists.freedesktop.org> On Behalf Of
>Christian König
>Sent: Wednesday, June 24, 2020 9:36 AM
>To: dri-devel@lists.freedesktop.org
>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@amd.com>
>---
> 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?

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

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
>
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RE: [PATCH 2/2] drm/ttm: make TT creation purely optional

[Ruhl, Michael J]

>-----Original Message-----
>From: dri-devel <dri-devel-bounces@lists.freedesktop.org> On Behalf Of
>Christian König
>Sent: Wednesday, June 24, 2020 9:36 AM
>To: dri-devel@lists.freedesktop.org
>Subject: [PATCH 2/2] drm/ttm: make TT creation purely optional
>
>We only need the page array when the BO is about to be accessed.
>
>So not only populate, but also create it on demand.
>
>Signed-off-by: Christian König <christian.koenig@amd.com>
>---
> drivers/gpu/drm/ttm/ttm_bo.c      | 26 ++++----------------------
> drivers/gpu/drm/ttm/ttm_bo_util.c |  9 +++++++--
> drivers/gpu/drm/ttm/ttm_bo_vm.c   |  5 +++++
> 3 files changed, 16 insertions(+), 24 deletions(-)
>
>diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
>index 15f9b19fa00d..0e0a9dadf3ed 100644
>--- a/drivers/gpu/drm/ttm/ttm_bo.c
>+++ b/drivers/gpu/drm/ttm/ttm_bo.c
>@@ -667,13 +667,8 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo,
> 	placement.num_busy_placement = 0;
> 	bdev->driver->evict_flags(bo, &placement);
>
>-	if (!placement.num_placement &&
>!placement.num_busy_placement) {
>-		ret = ttm_bo_pipeline_gutting(bo);
>-		if (ret)
>-			return ret;
>-
>-		return ttm_tt_create(bo, false);
>-	}
>+	if (!placement.num_placement &&
>!placement.num_busy_placement)
>+		return ttm_bo_pipeline_gutting(bo);
>
> 	evict_mem = bo->mem;
> 	evict_mem.mm_node = NULL;
>@@ -1200,13 +1195,8 @@ int ttm_bo_validate(struct ttm_buffer_object *bo,
> 	/*
> 	 * Remove the backing store if no placement is given.
> 	 */
>-	if (!placement->num_placement && !placement-
>>num_busy_placement) {
>-		ret = ttm_bo_pipeline_gutting(bo);
>-		if (ret)
>-			return ret;
>-
>-		return ttm_tt_create(bo, false);
>-	}
>+	if (!placement->num_placement && !placement-
>>num_busy_placement)
>+		return ttm_bo_pipeline_gutting(bo);
>
> 	/*
> 	 * Check whether we need to move buffer.
>@@ -1223,14 +1213,6 @@ int ttm_bo_validate(struct ttm_buffer_object *bo,
> 		ttm_flag_masked(&bo->mem.placement, new_flags,
> 				~TTM_PL_MASK_MEMTYPE);
> 	}
>-	/*
>-	 * We might need to add a TTM.
>-	 */
>-	if (bo->mem.mem_type == TTM_PL_SYSTEM && bo->ttm == NULL) {
>-		ret = ttm_tt_create(bo, true);
>-		if (ret)
>-			return ret;
>-	}
> 	return 0;
> }
> EXPORT_SYMBOL(ttm_bo_validate);
>diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c
>b/drivers/gpu/drm/ttm/ttm_bo_util.c
>index 52d2b71f1588..f8414f820350 100644
>--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
>+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
>@@ -580,12 +580,17 @@ static int ttm_bo_kmap_ttm(struct
>ttm_buffer_object *bo,
> 		.interruptible = false,
> 		.no_wait_gpu = false
> 	};
>-	struct ttm_tt *ttm = bo->ttm;
>+	struct ttm_tt *ttm;
> 	pgprot_t prot;
> 	int ret;
>
>-	BUG_ON(!ttm);
>+	if (!bo->ttm) {
>+		ret = ttm_tt_create(bo, true);

Would it be reasonable to move the NULL check into ttm_tt_create()?

Kind of an opposite path NULL check, but it makes the path a little
more clean.

Mike

>+		if (ret)
>+			return ret;
>+	}
>
>+	ttm = bo->ttm;
> 	ret = ttm_tt_populate(ttm, &ctx);
> 	if (ret)
> 		return ret;
>diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c
>b/drivers/gpu/drm/ttm/ttm_bo_vm.c
>index 0ad30b112982..bdfed6725d6f 100644
>--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
>+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
>@@ -349,6 +349,11 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct
>vm_fault *vmf,
>
> 		};
>
>+		if (!bo->ttm && ttm_tt_create(bo, true)) {
>+			ret = VM_FAULT_OOM;
>+			goto out_io_unlock;
>+		}
>+
> 		ttm = bo->ttm;
> 		if (ttm_tt_populate(bo->ttm, &ctx)) {
> 			ret = VM_FAULT_OOM;
>--
>2.17.1
>
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>dri-devel@lists.freedesktop.org
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Re: [PATCH 1/2] drm/ttm: cleanup ttm_mem_type_manager_func.get_node interface

[Christian König]

Am 26.06.20 um 19:39 schrieb Ruhl, Michael J:
>> -----Original Message-----
>> From: dri-devel <dri-devel-bounces@lists.freedesktop.org> On Behalf Of
>> Christian König
>> Sent: Wednesday, June 24, 2020 9:36 AM
>> To: dri-devel@lists.freedesktop.org
>> 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@amd.com>
>> ---
>> 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@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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