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dma-buf: warn about dma_fence_array container rules v2

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It's not allowed to nest another dma_fence container into a dma_fence_array
or otherwise we can run into recursion.

Warn about that when we create a dma_fence_array.

v2: fix comment style and typo in the warning pointed out by Thomas

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220204100429.2049-3-christian.koenig@amd.com
This commit is contained in:
Christian König 2022-01-19 11:40:21 +01:00
parent 976b6d97c6
commit 0fd9803b98
1 changed files with 14 additions and 0 deletions
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14
drivers/dma-buf/dma-fence-array.c
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@ -176,6 +176,20 @@ struct dma_fence_array *dma_fence_array_create(int num_fences,
array->base.error = PENDING_ERROR;
/*
* dma_fence_array objects should never contain any other fence
* containers or otherwise we run into recursion and potential kernel
* stack overflow on operations on the dma_fence_array.
*
* The correct way of handling this is to flatten out the array by the
* caller instead.
*
* Enforce this here by checking that we don't create a dma_fence_array
* with any container inside.
*/
while (num_fences--)
WARN_ON(dma_fence_is_container(fences[num_fences]));
return array;
}
EXPORT_SYMBOL(dma_fence_array_create);