gpu: nvgpu: VM unmap refactoring

Re-organize the unmap code to be better split between OS specific
requirements and common core requirements. The new code flow works
as follows:

  nvgpu_vm_unmap()

Is the primary entrance to the unmap path. It takes a VM and a GPU
virtual address to unmap. There's also an optional batch mapping
struct.

This function is responsible for making sure there is a real buffer
and that if it's being called on a fixed mapping then the mapping
will definitely be freed (since buffers are ref-counted). Then this
function decrements the ref-count and returns.

If the ref-count hits zero then __nvgpu_vm_unmap_ref() is called
which just calls __nvgpu_vm_unmap() with the relevant batch struct
if present. This is where the real work is done. __nvgpu_vm_unmap()
clears the GMMU mapping, removes the mapped buffer from the various
lists and trees it may be in and then calls the
nvgpu_vm_unmap_system() function. This function handles any OS
specific stuff and must be defined by all VM OS implementations.

There's a a short cut used by some other core VM code to free
mappings without going through nvgpu_vm_map(). Mostly they just
directly decrement the mapping ref-count which can then call
__nvgpu_vm_unmap_ref() if the ref-count hits zero.

JIRA NVGPU-30
JIRA NVGPU-71

Change-Id: Ic626d37ab936819841bab45214f027b40ffa4e5a
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1583982
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>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/gpu/nvgpu/common/mm/vm_area.c b/drivers/gpu/nvgpu/common/mm/vm_area.c
index 88758b85..fddec357 100644
--- a/drivers/gpu/nvgpu/common/mm/vm_area.c
+++ b/drivers/gpu/nvgpu/common/mm/vm_area.c
@@ -208,7 +208,7 @@ int nvgpu_vm_area_free(struct vm_gk20a *vm, u64 addr)
                                        &vm_area->buffer_list_head,
                                        nvgpu_mapped_buf, buffer_list) {
                 nvgpu_list_del(&buffer->buffer_list);
-                nvgpu_ref_put(&buffer->ref, nvgpu_vm_unmap_locked_ref);
+                nvgpu_ref_put(&buffer->ref, __nvgpu_vm_unmap_ref);
         }
 
         /* if this was a sparse mapping, free the va */