3.1 General format of the API:
struct dma_async_tx_descriptor *
-async_<operation>(<op specific parameters>,
- enum async_tx_flags flags,
- struct dma_async_tx_descriptor *dependency,
- dma_async_tx_callback callback_routine,
- void *callback_parameter);
+async_<operation>(<op specific parameters>, struct async_submit ctl *submit)
3.2 Supported operations:
memcpy - memory copy between a source and a destination buffer
xor_val - xor a series of source buffers and set a flag if the
result is zero. The implementation attempts to prevent
writes to memory
+pq - generate the p+q (raid6 syndrome) from a series of source buffers
+pq_val - validate that a p and or q buffer are in sync with a given series of
+ sources
+datap - (raid6_datap_recov) recover a raid6 data block and the p block
+ from the given sources
+2data - (raid6_2data_recov) recover 2 raid6 data blocks from the given
+ sources
3.3 Descriptor management:
The return value is non-NULL and points to a 'descriptor' when the operation
Perform a xor->copy->xor operation where each operation depends on the
result from the previous operation:
-void complete_xor_copy_xor(void *param)
+void callback(void *param)
{
- printk("complete\n");
+ struct completion *cmp = param;
+
+ complete(cmp);
}
-int run_xor_copy_xor(struct page **xor_srcs,
- int xor_src_cnt,
- struct page *xor_dest,
- size_t xor_len,
- struct page *copy_src,
- struct page *copy_dest,
- size_t copy_len)
+void run_xor_copy_xor(struct page **xor_srcs,
+ int xor_src_cnt,
+ struct page *xor_dest,
+ size_t xor_len,
+ struct page *copy_src,
+ struct page *copy_dest,
+ size_t copy_len)
{
struct dma_async_tx_descriptor *tx;
+ addr_conv_t addr_conv[xor_src_cnt];
+ struct async_submit_ctl submit;
+ addr_conv_t addr_conv[NDISKS];
+ struct completion cmp;
+
+ init_async_submit(&submit, ASYNC_TX_XOR_DROP_DST, NULL, NULL, NULL,
+ addr_conv);
+ tx = async_xor(xor_dest, xor_srcs, 0, xor_src_cnt, xor_len, &submit)
- tx = async_xor(xor_dest, xor_srcs, 0, xor_src_cnt, xor_len,
- ASYNC_TX_XOR_DROP_DST, NULL, NULL, NULL);
- tx = async_memcpy(copy_dest, copy_src, 0, 0, copy_len, tx, NULL, NULL);
- tx = async_xor(xor_dest, xor_srcs, 0, xor_src_cnt, xor_len,
- ASYNC_TX_XOR_DROP_DST | ASYNC_TX_ACK,
- tx, complete_xor_copy_xor, NULL);
+ submit->depend_tx = tx;
+ tx = async_memcpy(copy_dest, copy_src, 0, 0, copy_len, &submit);
+
+ init_completion(&cmp);
+ init_async_submit(&submit, ASYNC_TX_XOR_DROP_DST | ASYNC_TX_ACK, tx,
+ callback, &cmp, addr_conv);
+ tx = async_xor(xor_dest, xor_srcs, 0, xor_src_cnt, xor_len, &submit);
async_tx_issue_pending_all();
+
+ wait_for_completion(&cmp);
}
See include/linux/async_tx.h for more information on the flags. See the