This function allows to replace fences from the shared fence list when
we can gurantee that the operation represented by the original fence has
finished or no accesses to the resources protected by the dma_resv
object any more when the new fence finishes.
Then use this function in the amdkfd code when BOs are unmapped from the
process.
v2: add an example when this is usefull.
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/dma-buf/dma-resv.c | 45 +++++++++++++++++
.../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 49 +++----------------
include/linux/dma-resv.h | 2 +
3 files changed, 54 insertions(+), 42 deletions(-)
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index b51416405e86..509060861cf3 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -289,6 +289,51 @@ void dma_resv_add_shared_fence(struct dma_resv
*obj, struct dma_fence *fence)
}
EXPORT_SYMBOL(dma_resv_add_shared_fence);
+/**
+ * dma_resv_replace_fences - replace fences in the dma_resv obj
+ * @obj: the reservation object
+ * @context: the context of the fences to replace
+ * @replacement: the new fence to use instead
+ *
+ * Replace fences with a specified context with a new fence. Only
valid if the
+ * operation represented by the original fence has no longer access
to the
+ * resources represented by the dma_resv object when the new fence
completes.
+ *
+ * And example for using this is replacing a preemption fence with a
page table
+ * update fence which makes the resource inaccessible.
+ */
+void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context,
+ struct dma_fence *replacement)
+{
+ struct dma_resv_list *list;
+ struct dma_fence *old;
+ unsigned int i;
+
+ dma_resv_assert_held(obj);
+
+ write_seqcount_begin(&obj->seq);
+
+ old = dma_resv_excl_fence(obj);
+ if (old->context == context) {
+ RCU_INIT_POINTER(obj->fence_excl, dma_fence_get(replacement));
+ dma_fence_put(old);
+ }
+
+ list = dma_resv_shared_list(obj);
+ for (i = 0; list && i < list->shared_count; ++i) {
+ old = rcu_dereference_protected(list->shared[i],
+ dma_resv_held(obj));
+ if (old->context != context)
+ continue;
+
+ rcu_assign_pointer(list->shared[i],
dma_fence_get(replacement));
+ dma_fence_put(old);
+ }
+
+ write_seqcount_end(&obj->seq);
+}
+EXPORT_SYMBOL(dma_resv_replace_fences);
+
/**
* dma_resv_add_excl_fence - Add an exclusive fence.
* @obj: the reservation object
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index f9bab963a948..b6f266f612ea 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -253,53 +253,18 @@ void amdgpu_amdkfd_release_notify(struct
amdgpu_bo *bo)
static int amdgpu_amdkfd_remove_eviction_fence(struct amdgpu_bo *bo,
struct amdgpu_amdkfd_fence *ef)
{
- struct dma_resv *resv = bo->tbo.base.resv;
- struct dma_resv_list *old, *new;
- unsigned int i, j, k;
+ struct dma_fence *replacement;
if (!ef)
return -EINVAL;
- old = dma_resv_shared_list(resv);
- if (!old)
- return 0;
-
- new = kmalloc(struct_size(new, shared, old->shared_max),
GFP_KERNEL);
- if (!new)
- return -ENOMEM;
-
- /* Go through all the shared fences in the resevation object and
sort
- * the interesting ones to the end of the list.
+ /* TODO: Instead of block before we should use the fence of the
page
+ * table update and TLB flush here directly.
