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dma-fence: Store the timestamp in the same union as the cb_list

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The timestamp and the cb_list are mutually exclusive, the cb_list can
only be added to prior to being signaled (and once signaled we drain),
while the timestamp is only valid upon being signaled. Both the
timestamp and the cb_list are only valid while the fence is alive, and
as soon as no references are held can be replaced by the rcu_head.

By reusing the union for the timestamp, we squeeze the base dma_fence
struct to 64 bytes on x86-64.

v2: Sort the union chronologically

Suggested-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christian König <christian.koenig@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>.
Link: https://patchwork.freedesktop.org/patch/msgid/20190817153022.5749-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson
2019-08-17 16:30:22 +01:00
parent 0fc89b6802
commit f2cb60e9a3
4 changed files with 38 additions and 18 deletions
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16
drivers/dma-buf/dma-fence.c
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@@ -129,6 +129,7 @@ EXPORT_SYMBOL(dma_fence_context_alloc);
int dma_fence_signal_locked(struct dma_fence *fence)
{
struct dma_fence_cb *cur, *tmp;
struct list_head cb_list;
lockdep_assert_held(fence->lock);
@@ -136,16 +137,16 @@ int dma_fence_signal_locked(struct dma_fence *fence)
&fence->flags)))
return -EINVAL;
/* Stash the cb_list before replacing it with the timestamp */
list_replace(&fence->cb_list, &cb_list);
fence->timestamp = ktime_get();
set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags);
trace_dma_fence_signaled(fence);
if (!list_empty(&fence->cb_list)) {
list_for_each_entry_safe(cur, tmp, &fence->cb_list, node) {
INIT_LIST_HEAD(&cur->node);
cur->func(fence, cur);
}
INIT_LIST_HEAD(&fence->cb_list);
list_for_each_entry_safe(cur, tmp, &cb_list, node) {
INIT_LIST_HEAD(&cur->node);
cur->func(fence, cur);
}
return 0;
@@ -231,7 +232,8 @@ void dma_fence_release(struct kref *kref)
trace_dma_fence_destroy(fence);
if (WARN(!list_empty(&fence->cb_list),
if (WARN(!list_empty(&fence->cb_list) &&
!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags),
"Fence %s:%s:%llx:%llx released with pending signals!\n",
fence->ops->get_driver_name(fence),
fence->ops->get_timeline_name(fence),