[PATCH] drm/ttm: revert "Fix COW check"

[Christian König]

This reverts commit 85fd4a8a84316166640102676a356755ddec80e0.

Daniel pointed out that even PROT_READ can cause a BUG_ON() with this.

Signed-off-by: Christian König <christian.koenig at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c  |  3 +--
 drivers/gpu/drm/nouveau/nouveau_gem.c    |  3 +--
 drivers/gpu/drm/radeon/radeon_gem.c      |  3 +--
 drivers/gpu/drm/ttm/ttm_bo_vm.c          | 14 +-------------
 drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c |  1 -
 include/drm/ttm/ttm_bo_api.h             |  4 ----
 6 files changed, 4 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index 0d65c9d2144e..9cf4beaf646c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -79,8 +79,7 @@ static const struct vm_operations_struct amdgpu_gem_vm_ops = {
 	.fault = amdgpu_gem_fault,
 	.open = ttm_bo_vm_open,
 	.close = ttm_bo_vm_close,
-	.access = ttm_bo_vm_access,
-	.mprotect = ttm_bo_vm_mprotect
+	.access = ttm_bo_vm_access
 };
 
 static void amdgpu_gem_object_free(struct drm_gem_object *gobj)
diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
index 164ea564bb7a..5b27845075a1 100644
--- a/drivers/gpu/drm/nouveau/nouveau_gem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
@@ -70,8 +70,7 @@ static const struct vm_operations_struct nouveau_ttm_vm_ops = {
 	.fault = nouveau_ttm_fault,
 	.open = ttm_bo_vm_open,
 	.close = ttm_bo_vm_close,
-	.access = ttm_bo_vm_access,
-	.mprotect = ttm_bo_vm_mprotect
+	.access = ttm_bo_vm_access
 };
 
 void
diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
index c19ad07eb7b5..458f92a70887 100644
--- a/drivers/gpu/drm/radeon/radeon_gem.c
+++ b/drivers/gpu/drm/radeon/radeon_gem.c
@@ -77,8 +77,7 @@ static const struct vm_operations_struct radeon_gem_vm_ops = {
 	.fault = radeon_gem_fault,
 	.open = ttm_bo_vm_open,
 	.close = ttm_bo_vm_close,
-	.access = ttm_bo_vm_access,
-	.mprotect = ttm_bo_vm_mprotect
+	.access = ttm_bo_vm_access
 };
 
 static void radeon_gem_object_free(struct drm_gem_object *gobj)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index fb325bad5db6..f56be5bc0861 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -542,29 +542,17 @@ int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
 }
 EXPORT_SYMBOL(ttm_bo_vm_access);
 
-int ttm_bo_vm_mprotect(struct vm_area_struct *vma, unsigned long start,
-		       unsigned long end, unsigned long newflags)
-{
-	/* Enforce no COW since would have really strange behavior with it. */
-	if (is_cow_mapping(newflags) && (newflags & VM_WRITE))
-		return -EINVAL;
-
-	return 0;
-}
-EXPORT_SYMBOL(ttm_bo_vm_mprotect);
-
 static const struct vm_operations_struct ttm_bo_vm_ops = {
 	.fault = ttm_bo_vm_fault,
 	.open = ttm_bo_vm_open,
 	.close = ttm_bo_vm_close,
 	.access = ttm_bo_vm_access,
-	.mprotect = ttm_bo_vm_mprotect,
 };
 
 int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
 {
 	/* Enforce no COW since would have really strange behavior with it. */
-	if (is_cow_mapping(vma->vm_flags) && (vma->vm_flags & VM_WRITE))
+	if (is_cow_mapping(vma->vm_flags))
 		return -EINVAL;
 
 	ttm_bo_get(bo);
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
index e4bf7dc99320..e6b1f98ec99f 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
@@ -61,7 +61,6 @@ int vmw_mmap(struct file *filp, struct vm_area_struct *vma)
 		.fault = vmw_bo_vm_fault,
 		.open = ttm_bo_vm_open,
 		.close = ttm_bo_vm_close,
-		.mprotect = ttm_bo_vm_mprotect,
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 		.huge_fault = vmw_bo_vm_huge_fault,
 #endif
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 40eb95875355..f681bbdbc698 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -605,10 +605,6 @@ void ttm_bo_vm_close(struct vm_area_struct *vma);
 
 int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
 		     void *buf, int len, int write);
-
-int ttm_bo_vm_mprotect(struct vm_area_struct *vma, unsigned long start,
-		       unsigned long end, unsigned long newflags);
-
 bool ttm_bo_delayed_delete(struct ttm_device *bdev, bool remove_all);
 
 vm_fault_t ttm_bo_vm_dummy_page(struct vm_fault *vmf, pgprot_t prot);
-- 
2.25.1