Revert "drm/amdgpu: Use dma_buf from GEM object instance"

This reverts commit 515986100d176663d0a03219a3056e4252f729e6.

The dma_buf field in struct drm_gem_object is not stable over the
object instance's lifetime. The field becomes NULL when user space
releases the final GEM handle on the buffer object. This resulted
in a NULL-pointer deref.

Workarounds in commit 5307dce878d4 ("drm/gem: Acquire references on
GEM handles for framebuffers") and commit f6bfc9afc751 ("drm/framebuffer:
Acquire internal references on GEM handles") only solved the problem
partially. They especially don't work for buffer objects without a DRM
framebuffer associated.

Hence, this revert to going back to using .import_attach->dmabuf.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://lore.kernel.org/r/20250715082635.34974-1-tzimmermann@suse.de

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
index ff98c87b2e0b91665fb6a9b9c0045df4f9ada1fd..5743ebb2f1b7cf54b1ae21ce3b9acdf63469819b 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
@@ -514,7 +514,7 @@ bool amdgpu_dmabuf_is_xgmi_accessible(struct amdgpu_device *adev,
                return false;
 
        if (drm_gem_is_imported(obj)) {
-               struct dma_buf *dma_buf = obj->dma_buf;
+               struct dma_buf *dma_buf = obj->import_attach->dmabuf;
 
                if (dma_buf->ops != &amdgpu_dmabuf_ops)
                        /* No XGMI with non AMD GPUs */

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index 6626a6e64ff5f8b67d99f30bfaee4aafee7e50fb..d1ccbfcf21fa62a8d4fe1b8f020cf00d34efe1ab 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -317,7 +317,8 @@ static int amdgpu_gem_object_open(struct drm_gem_object *obj,
         */
        if (!vm->is_compute_context || !vm->process_info)
                return 0;
-       if (!drm_gem_is_imported(obj) || !dma_buf_is_dynamic(obj->dma_buf))
+       if (!drm_gem_is_imported(obj) ||
+           !dma_buf_is_dynamic(obj->import_attach->dmabuf))
                return 0;
        mutex_lock_nested(&vm->process_info->lock, 1);
        if (!WARN_ON(!vm->process_info->eviction_fence)) {

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 5cacf5717016aaa64968be485805e0c48f88cb10..8777ed8facd6b5caf76d7b9ee504d27240b51831 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -1276,7 +1276,7 @@ int amdgpu_vm_bo_update(struct amdgpu_device *adev, struct amdgpu_bo_va *bo_va,
                struct drm_gem_object *obj = &bo->tbo.base;
 
                if (drm_gem_is_imported(obj) && bo_va->is_xgmi) {
-                       struct dma_buf *dma_buf = obj->dma_buf;
+                       struct dma_buf *dma_buf = obj->import_attach->dmabuf;
                        struct drm_gem_object *gobj = dma_buf->priv;
                        struct amdgpu_bo *abo = gem_to_amdgpu_bo(gobj);