gpu: nvgpu: Remove user_mapped from mapped_buf

Remove the always true field 'user_mapped' from the mapped_buf
struct. All mapped_bufs are mapped by a user request since they
always originate from a dma_buf (for Linux, that is). As such
there is a fair amount of logic that could be deleted.

Linux specific: the own_mem_ref field was also be deleted. The
logic of only storing a dma_buf ref when the buffer is mapped
for the first time by a user is easy: when the mapped buffer is
found in the map cache release the outstanding dma_buf ref taken
earlier on in the map path. If the map cache does not have the
buffer simply let the higher level map code keep the dma_buf ref.

The dma_buf ref is released when the nvgpu_vm_unmap_system()
call-back is called by the unmap path.

JIRA NVGPU-30
JIRA NVGPU-71

Change-Id: I229d136713812a7332bdadd5ebacd85d983bbbf0
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1583983
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/common/linux/cde.c

@@ -1050,7 +1050,6 @@ __releases(&l->cde_app->mutex)
 				 NVGPU_AS_MAP_BUFFER_FLAGS_DIRECT_KIND_CTRL,
 				 NV_KIND_INVALID,
 				 compbits_kind, /* incompressible kind */
-				 true,
 				 gk20a_mem_flag_none,
 				 map_offset, map_size,
 				 NULL);

drivers/gpu/nvgpu/common/linux/vm.c

@@ -227,7 +227,6 @@ static u64 __nvgpu_vm_find_mapping(struct vm_gk20a *vm,
 				   u64 offset_align,
 				   u32 flags,
 				   int kind,
-				   bool user_mapped,
 				   int rw_flag)
 {
 	struct gk20a *g = gk20a_from_vm(vm);
@@ -251,22 +250,13 @@ static u64 __nvgpu_vm_find_mapping(struct vm_gk20a *vm,
 	if (mapped_buffer->flags != flags)
 		return 0;
 
-	/* mark the buffer as used */
+	/*
-	if (user_mapped) {
+	 * If we find the mapping here then that means we have mapped it already
-		if (mapped_buffer->user_mapped == 0)
+	 * and already have a dma_buf ref to the underlying buffer. As such
-			vm->num_user_mapped_buffers++;
+	 * release the ref taken earlier in the map path.
-		mapped_buffer->user_mapped++;
+	 */
+	dma_buf_put(mapped_buffer->dmabuf);
 
-		/* If the mapping comes from user space, we own
-		 * the handle ref. Since we reuse an
-		 * existing mapping here, we need to give back those
-		 * refs once in order not to leak.
-		 */
-		if (mapped_buffer->own_mem_ref)
-			dma_buf_put(mapped_buffer->dmabuf);
-		else
-			mapped_buffer->own_mem_ref = true;
-	}
 	nvgpu_ref_get(&mapped_buffer->ref);
 
 	nvgpu_log(g, gpu_dbg_map,
@@ -329,7 +319,6 @@ u64 nvgpu_vm_map_linux(struct vm_gk20a *vm,
 		       u32 flags,
 		       s16 compr_kind,
 		       s16 incompr_kind,
-		       bool user_mapped,
 		       int rw_flag,
 		       u64 buffer_offset,
 		       u64 mapping_size,
@@ -367,7 +356,7 @@ u64 nvgpu_vm_map_linux(struct vm_gk20a *vm,
 		map_key_kind = compr_kind;
 	}
 
-	if (user_mapped && vm->userspace_managed &&
+	if (vm->userspace_managed &&
 	    !(flags & NVGPU_AS_MAP_BUFFER_FLAGS_FIXED_OFFSET)) {
 		nvgpu_err(g, "non-fixed-offset mapping not available on "
 			  "userspace managed address spaces");
@@ -380,8 +369,7 @@ u64 nvgpu_vm_map_linux(struct vm_gk20a *vm,
 	if (!vm->userspace_managed) {
 		map_offset = __nvgpu_vm_find_mapping(
 			vm, dmabuf, offset_align,
-			flags, map_key_kind,
+			flags, map_key_kind, rw_flag);
-			user_mapped, rw_flag);
 		if (map_offset) {
 			nvgpu_mutex_release(&vm->update_gmmu_lock);
 			return map_offset;
@@ -545,8 +533,6 @@ u64 nvgpu_vm_map_linux(struct vm_gk20a *vm,
 	mapped_buffer->flags       = flags;
 	mapped_buffer->kind        = map_key_kind;
 	mapped_buffer->va_allocated = va_allocated;
-	mapped_buffer->user_mapped = user_mapped ? 1 : 0;
-	mapped_buffer->own_mem_ref = user_mapped;
 	nvgpu_init_list_node(&mapped_buffer->buffer_list);
 	nvgpu_ref_init(&mapped_buffer->ref);
 
@@ -555,8 +541,8 @@ u64 nvgpu_vm_map_linux(struct vm_gk20a *vm,
 		nvgpu_err(g, "failed to insert into mapped buffer tree");
 		goto clean_up;
 	}
-	if (user_mapped)
+
-		vm->num_user_mapped_buffers++;
+	vm->num_user_mapped_buffers++;
 
 	if (vm_area) {
 		nvgpu_list_add_tail(&mapped_buffer->buffer_list,
@@ -626,7 +612,7 @@ int nvgpu_vm_map_buffer(struct vm_gk20a *vm,
 	}
 
 	ret_va = nvgpu_vm_map_linux(vm, dmabuf, *offset_align,
-				    flags, compr_kind, incompr_kind, true,
+				    flags, compr_kind, incompr_kind,
 				    gk20a_mem_flag_none,
 				    buffer_offset,
 				    mapping_size,
@@ -655,6 +641,5 @@ void nvgpu_vm_unmap_system(struct nvgpu_mapped_buf *mapped_buffer)
 	gk20a_mm_unpin(dev_from_vm(vm), mapped_buffer->dmabuf,
 		       mapped_buffer->sgt);
 
-	if (mapped_buffer->own_mem_ref)
+	dma_buf_put(mapped_buffer->dmabuf);
-		dma_buf_put(mapped_buffer->dmabuf);
 }

drivers/gpu/nvgpu/common/mm/vm.c

@@ -672,11 +672,9 @@ int nvgpu_vm_get_buffers(struct vm_gk20a *vm,
 	nvgpu_rbtree_enum_start(0, &node, vm->mapped_buffers);
 	while (node) {
 		mapped_buffer = mapped_buffer_from_rbtree_node(node);
-		if (mapped_buffer->user_mapped) {
+		buffer_list[i] = mapped_buffer;
-			buffer_list[i] = mapped_buffer;
+		nvgpu_ref_get(&mapped_buffer->ref);
-			nvgpu_ref_get(&mapped_buffer->ref);
+		i++;
-			i++;
-		}
 		nvgpu_rbtree_enum_next(&node, node);
 	}
 

drivers/gpu/nvgpu/include/nvgpu/linux/vm.h

@@ -72,7 +72,6 @@ u64 nvgpu_vm_map_linux(struct vm_gk20a *vm,
 			*/
 		       s16 incompr_kind,
 
-		       bool user_mapped,
 		       int rw_flag,
 		       u64 buffer_offset,
 		       u64 mapping_size,

drivers/gpu/nvgpu/include/nvgpu/vm.h

@@ -96,8 +96,7 @@ struct nvgpu_mapped_buf {
 	struct dma_buf *dmabuf;
 	struct sg_table *sgt;
 	struct nvgpu_ref ref;
-	u32 user_mapped;
+
-	bool own_mem_ref;
 	u32 pgsz_idx;
 	u32 ctag_offset;
 	u32 ctag_lines;