[Intel-gfx] [PATCH 04/26] dma-buf: use new iterator in dma_resv_get_fences v2

Christian König
2021-09-22T12:45:18Z

This makes the function much simpler since the complex
retry logic is now handled elsewhere.

v2: use sizeof(void*) instead

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
drivers/dma-buf/dma-resv.c | 108 +++++++++++++------------------------
1 file changed, 36 insertions(+), 72 deletions(-)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 556d5afafe3f..cde97e4e547f 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -530,99 +530,63 @@ EXPORT_SYMBOL(dma_resv_copy_fences);
* dma_resv_get_fences - Get an object's shared and exclusive
* fences without update side lock held
* @obj: the reservation object
- * @pfence_excl: the returned exclusive fence (or NULL)
- * @pshared_count: the number of shared fences returned
- * @pshared: the array of shared fence ptrs returned (array is krealloc'd to
+ * @fence_excl: the returned exclusive fence (or NULL)
+ * @shared_count: the number of shared fences returned
+ * @shared: the array of shared fence ptrs returned (array is krealloc'd to
* the required size, and must be freed by caller)
*
* Retrieve all fences from the reservation object. If the pointer for the
* exclusive fence is not specified the fence is put into the array of the
* shared fences as well. Returns either zero or -ENOMEM.
*/
-int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
- unsigned int *pshared_count,
- struct dma_fence ***pshared)
+int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **fence_excl,
+ unsigned int *shared_count, struct dma_fence ***shared)
{
- struct dma_fence **shared = NULL;
- struct dma_fence *fence_excl;
- unsigned int shared_count;
- int ret = 1;
-
- do {
- struct dma_resv_list *fobj;
- unsigned int i, seq;
- size_t sz = 0;
-
- shared_count = i = 0;
-
- rcu_read_lock();
- seq = read_seqcount_begin(&obj->seq);
+ struct dma_resv_iter cursor;
+ struct dma_fence *fence;

- fence_excl = dma_resv_excl_fence(obj);
- if (fence_excl && !dma_fence_get_rcu(fence_excl))
- goto unlock;
+ *shared_count = 0;
+ *shared = NULL;

- fobj = dma_resv_shared_list(obj);
- if (fobj)
- sz += sizeof(*shared) * fobj->shared_max;
+ if (fence_excl)
+ *fence_excl = NULL;

- if (!pfence_excl && fence_excl)
- sz += sizeof(*shared);
+ dma_resv_iter_begin(&cursor, obj, true);
+ dma_resv_for_each_fence_unlocked(&cursor, fence) {

- if (sz) {
- struct dma_fence **nshared;
+ if (dma_resv_iter_is_restarted(&cursor)) {
+ unsigned int count;

- nshared = krealloc(shared, sz,
- GFP_NOWAIT | __GFP_NOWARN);
- if (!nshared) {
- rcu_read_unlock();
+ while (*shared_count)
+ dma_fence_put((*shared)[--(*shared_count)]);

- dma_fence_put(fence_excl);
- fence_excl = NULL;
+ if (fence_excl)
+ dma_fence_put(*fence_excl);

- nshared = krealloc(shared, sz, GFP_KERNEL);
- if (nshared) {
- shared = nshared;
- continue;
- }
+ count = cursor.fences ? cursor.fences->shared_count : 0;
+ count += fence_excl ? 0 : 1;

- ret = -ENOMEM;
- break;
- }
- shared = nshared;
- shared_count = fobj ? fobj->shared_count : 0;
- for (i = 0; i < shared_count; ++i) {
- shared[i] = rcu_dereference(fobj->shared[i]);
- if (!dma_fence_get_rcu(shared[i]))
- break;
+ /* Eventually re-allocate the array */
+ *shared = krealloc_array(*shared, count,
+ sizeof(void *),
+ GFP_KERNEL);
+ if (count && !*shared) {
+ dma_resv_iter_end(&cursor);
+ return -ENOMEM;
}
}

- if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
- while (i--)
- dma_fence_put(shared[i]);
- dma_fence_put(fence_excl);
- goto unlock;
- }
-
- ret = 0;
-unlock:
- rcu_read_unlock();
- } while (ret);
-
- if (pfence_excl)
- *pfence_excl = fence_excl;
- else if (fence_excl)
- shared[shared_count++] = fence_excl;
+ if (dma_resv_iter_is_exclusive(&cursor) && fence_excl)
+ *fence_excl = fence;
+ else
+ (*shared)[(*shared_count)++] = fence;

- if (!shared_count) {
- kfree(shared);
- shared = NULL;
+ /* Don't drop the reference */
+ fence = NULL;
}
+ dma_resv_iter_end(&cursor);

- *pshared_count = shared_count;
- *pshared = shared;
- return ret;
+ return 0;
}
EXPORT_SYMBOL_GPL(dma_resv_get_fences);

--
2.25.1