async_tx: kill ASYNC_TX_DEP_ACK flag

In support of inter-channel chaining async_tx utilizes an ack flag to
gate whether a dependent operation can be chained to another.  While the
flag is not set the chain can be considered open for appending.  Setting
the ack flag closes the chain and flags the descriptor for garbage
collection.  The ASYNC_TX_DEP_ACK flag essentially means "close the
chain after adding this dependency".  Since each operation can only have
one child the api now implicitly sets the ack flag at dependency
submission time.  This removes an unnecessary management burden from
clients of the api.

[ Impact: clean up and enforce one dependency per operation ]

Reviewed-by: Andre Noll <maan@systemlinux.org>
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 4 insertions, 5 deletions

diff --git a/Documentation/crypto/async-tx-api.txt b/Documentation/crypto/async-tx-api.txt
index 4af12180d191..76feda8541dc 100644
--- a/Documentation/crypto/async-tx-api.txt
+++ b/Documentation/crypto/async-tx-api.txt
@@ -80,8 +80,8 @@ acknowledged by the application before the offload engine driver is allowed to
 recycle (or free) the descriptor.  A descriptor can be acked by one of the
 following methods:
 1/ setting the ASYNC_TX_ACK flag if no child operations are to be submitted
-2/ setting the ASYNC_TX_DEP_ACK flag to acknowledge the parent
-   descriptor of a new operation.
+2/ submitting an unacknowledged descriptor as a dependency to another
+   async_tx call will implicitly set the acknowledged state.
 3/ calling async_tx_ack() on the descriptor.
 
 3.4 When does the operation execute?
@@ -136,10 +136,9 @@ int run_xor_copy_xor(struct page **xor_srcs,
 
         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,
-                          ASYNC_TX_DEP_ACK, tx, 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_DEP_ACK | ASYNC_TX_ACK,
+                       ASYNC_TX_XOR_DROP_DST | ASYNC_TX_ACK,
                        tx, complete_xor_copy_xor, NULL);
 
         async_tx_issue_pending_all();