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async_tx: fix dma_wait_for_async_tx
Fix dma_wait_for_async_tx to not loop forever in the case where a dependency chain is longer than two entries. This condition will not happen with current in-kernel drivers, but fix it for future drivers. Found-by: Saeed Bishara <saeed.bishara@gmail.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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@ -80,6 +80,7 @@ dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)
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{
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enum dma_status status;
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struct dma_async_tx_descriptor *iter;
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struct dma_async_tx_descriptor *parent;
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if (!tx)
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return DMA_SUCCESS;
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@ -87,8 +88,15 @@ dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)
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/* poll through the dependency chain, return when tx is complete */
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do {
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iter = tx;
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while (iter->cookie == -EBUSY)
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iter = iter->parent;
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/* find the root of the unsubmitted dependency chain */
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while (iter->cookie == -EBUSY) {
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parent = iter->parent;
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if (parent && parent->cookie == -EBUSY)
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iter = iter->parent;
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else
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break;
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}
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status = dma_sync_wait(iter->chan, iter->cookie);
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} while (status == DMA_IN_PROGRESS || (iter != tx));
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