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>

1 files changed, 12 insertions, 27 deletions

diff --git a/drivers/gpu/nvgpu/common/linux/vm.c b/drivers/gpu/nvgpu/common/linux/vm.c
index feb124f8..40e3d6ea 100644
--- a/drivers/gpu/nvgpu/common/linux/vm.c
+++ b/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 (mapped_buffer->user_mapped == 0)
-                        vm->num_user_mapped_buffers++;
-                mapped_buffer->user_mapped++;
+        /*
+         * If we find the mapping here then that means we have mapped it already
+         * and already have a dma_buf ref to the underlying buffer. As such
+         * release the ref taken earlier in the map path.
+         */
+        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,
-                        user_mapped, rw_flag);
+                        flags, map_key_kind, 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);
 }