[PATCH drm-misc-next v2 1/2] drm/gpuvm: fall back to drm_exec_lock_obj()

From: Danilo Krummrich
Date: Wed Nov 29 2023 - 17:08:55 EST


Fall back to drm_exec_lock_obj() if num_fences is zero for the
drm_gpuvm_prepare_* function family.

Otherwise dma_resv_reserve_fences() would actually allocate slots even
though num_fences is zero.

Cc: Christian König <christian.koenig@xxxxxxx>
Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
---
drivers/gpu/drm/drm_gpuvm.c | 43 ++++++++++++++++++++++++++++++++-----
include/drm/drm_gpuvm.h | 23 +++-----------------
2 files changed, 41 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/drm_gpuvm.c b/drivers/gpu/drm/drm_gpuvm.c
index 54f5e8851de5..07a6676bc4f9 100644
--- a/drivers/gpu/drm/drm_gpuvm.c
+++ b/drivers/gpu/drm/drm_gpuvm.c
@@ -1085,6 +1085,37 @@ drm_gpuvm_put(struct drm_gpuvm *gpuvm)
}
EXPORT_SYMBOL_GPL(drm_gpuvm_put);

+static int
+exec_prepare_obj(struct drm_exec *exec, struct drm_gem_object *obj,
+ unsigned int num_fences)
+{
+ return num_fences ? drm_exec_prepare_obj(exec, obj, num_fences) :
+ drm_exec_lock_obj(exec, obj);
+}
+
+/**
+ * drm_gpuvm_prepare_vm() - prepare the GPUVMs common dma-resv
+ * @gpuvm: the &drm_gpuvm
+ * @exec: the &drm_exec context
+ * @num_fences: the amount of &dma_fences to reserve
+ *
+ * Calls drm_exec_prepare_obj() for the GPUVMs dummy &drm_gem_object; if
+ * @num_fences is zero drm_exec_lock_obj() is called instead.
+ *
+ * Using this function directly, it is the drivers responsibility to call
+ * drm_exec_init() and drm_exec_fini() accordingly.
+ *
+ * Returns: 0 on success, negative error code on failure.
+ */
+int
+drm_gpuvm_prepare_vm(struct drm_gpuvm *gpuvm,
+ struct drm_exec *exec,
+ unsigned int num_fences)
+{
+ return exec_prepare_obj(exec, gpuvm->r_obj, num_fences);
+}
+EXPORT_SYMBOL_GPL(drm_gpuvm_prepare_vm);
+
static int
__drm_gpuvm_prepare_objects(struct drm_gpuvm *gpuvm,
struct drm_exec *exec,
@@ -1095,7 +1126,7 @@ __drm_gpuvm_prepare_objects(struct drm_gpuvm *gpuvm,
int ret = 0;

for_each_vm_bo_in_list(gpuvm, extobj, &extobjs, vm_bo) {
- ret = drm_exec_prepare_obj(exec, vm_bo->obj, num_fences);
+ ret = exec_prepare_obj(exec, vm_bo->obj, num_fences);
if (ret)
break;
}
@@ -1116,7 +1147,7 @@ drm_gpuvm_prepare_objects_locked(struct drm_gpuvm *gpuvm,

drm_gpuvm_resv_assert_held(gpuvm);
list_for_each_entry(vm_bo, &gpuvm->extobj.list, list.entry.extobj) {
- ret = drm_exec_prepare_obj(exec, vm_bo->obj, num_fences);
+ ret = exec_prepare_obj(exec, vm_bo->obj, num_fences);
if (ret)
break;

@@ -1134,7 +1165,8 @@ drm_gpuvm_prepare_objects_locked(struct drm_gpuvm *gpuvm,
* @num_fences: the amount of &dma_fences to reserve
*
* Calls drm_exec_prepare_obj() for all &drm_gem_objects the given
- * &drm_gpuvm contains mappings of.
+ * &drm_gpuvm contains mappings of; if @num_fences is zero drm_exec_lock_obj()
+ * is called instead.
*
* Using this function directly, it is the drivers responsibility to call
* drm_exec_init() and drm_exec_fini() accordingly.
@@ -1171,7 +1203,8 @@ EXPORT_SYMBOL_GPL(drm_gpuvm_prepare_objects);
* @num_fences: the amount of &dma_fences to reserve
*
* Calls drm_exec_prepare_obj() for all &drm_gem_objects mapped between @addr
- * and @addr + @range.
+ * and @addr + @range; if @num_fences is zero drm_exec_lock_obj() is called
+ * instead.
*
* Returns: 0 on success, negative error code on failure.
*/
@@ -1186,7 +1219,7 @@ drm_gpuvm_prepare_range(struct drm_gpuvm *gpuvm, struct drm_exec *exec,
drm_gpuvm_for_each_va_range(va, gpuvm, addr, end) {
struct drm_gem_object *obj = va->gem.obj;

- ret = drm_exec_prepare_obj(exec, obj, num_fences);
+ ret = exec_prepare_obj(exec, obj, num_fences);
if (ret)
return ret;
}
diff --git a/include/drm/drm_gpuvm.h b/include/drm/drm_gpuvm.h
index f94fec9a8517..b3f82ec7fb17 100644
--- a/include/drm/drm_gpuvm.h
+++ b/include/drm/drm_gpuvm.h
@@ -544,26 +544,9 @@ struct drm_gpuvm_exec {
} extra;
};

-/**
- * drm_gpuvm_prepare_vm() - prepare the GPUVMs common dma-resv
- * @gpuvm: the &drm_gpuvm
- * @exec: the &drm_exec context
- * @num_fences: the amount of &dma_fences to reserve
- *
- * Calls drm_exec_prepare_obj() for the GPUVMs dummy &drm_gem_object.
- *
- * Using this function directly, it is the drivers responsibility to call
- * drm_exec_init() and drm_exec_fini() accordingly.
- *
- * Returns: 0 on success, negative error code on failure.
- */
-static inline int
-drm_gpuvm_prepare_vm(struct drm_gpuvm *gpuvm,
- struct drm_exec *exec,
- unsigned int num_fences)
-{
- return drm_exec_prepare_obj(exec, gpuvm->r_obj, num_fences);
-}
+int drm_gpuvm_prepare_vm(struct drm_gpuvm *gpuvm,
+ struct drm_exec *exec,
+ unsigned int num_fences);

int drm_gpuvm_prepare_objects(struct drm_gpuvm *gpuvm,
struct drm_exec *exec,
--
2.43.0