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dma-buf: make reservation_object_copy_fences rcu save

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Stop requiring that the src reservation object is locked for this operation.

Acked-by: Chunming Zhou <david1.zhou@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1504551766-5093-1-git-send-email-deathsimple@vodafone.de
This commit is contained in:
Christian König 2017-09-04 21:02:45 +02:00 committed by Alex Deucher
parent 6d281b1f79
commit 39e16ba16c
1 changed files with 42 additions and 14 deletions
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56
drivers/dma-buf/reservation.c
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@ -266,8 +266,7 @@ EXPORT_SYMBOL(reservation_object_add_excl_fence);
* @dst: the destination reservation object
* @src: the source reservation object
*
* Copy all fences from src to dst. Both src->lock as well as dst-lock must be
* held.
* Copy all fences from src to dst. dst-lock must be held.
*/
int reservation_object_copy_fences(struct reservation_object *dst,
struct reservation_object *src)
@ -277,33 +276,62 @@ int reservation_object_copy_fences(struct reservation_object *dst,
size_t size;
unsigned i;
src_list = reservation_object_get_list(src);
rcu_read_lock();
src_list = rcu_dereference(src->fence);
retry:
if (src_list) {
size = offsetof(typeof(*src_list),
shared[src_list->shared_count]);
unsigned shared_count = src_list->shared_count;
size = offsetof(typeof(*src_list), shared[shared_count]);
rcu_read_unlock();
dst_list = kmalloc(size, GFP_KERNEL);
if (!dst_list)
return -ENOMEM;
dst_list->shared_count = src_list->shared_count;
dst_list->shared_max = src_list->shared_count;
for (i = 0; i < src_list->shared_count; ++i)
dst_list->shared[i] =
dma_fence_get(src_list->shared[i]);
rcu_read_lock();
src_list = rcu_dereference(src->fence);
if (!src_list || src_list->shared_count > shared_count) {
kfree(dst_list);
goto retry;
}
dst_list->shared_count = 0;
dst_list->shared_max = shared_count;
for (i = 0; i < src_list->shared_count; ++i) {
struct dma_fence *fence;
fence = rcu_dereference(src_list->shared[i]);
if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
&fence->flags))
continue;
if (!dma_fence_get_rcu(fence)) {
kfree(dst_list);
src_list = rcu_dereference(src->fence);
goto retry;
}
if (dma_fence_is_signaled(fence)) {
dma_fence_put(fence);
continue;
}
dst_list->shared[dst_list->shared_count++] = fence;
}
} else {
dst_list = NULL;
}
new = dma_fence_get_rcu_safe(&src->fence_excl);
rcu_read_unlock();
kfree(dst->staged);
dst->staged = NULL;
src_list = reservation_object_get_list(dst);
old = reservation_object_get_excl(dst);
new = reservation_object_get_excl(src);
dma_fence_get(new);
preempt_disable();
write_seqcount_begin(&dst->seq);