docs: crypto: async-tx-api: fix broken code example

The code example fails to compile:

  1) addr_conv is defined twice, once as a VLA, which have been phased out

  2) submit is not a pointer, but is still dereferenced with ->

  3) The first call to async_xor() lacked the trailing semicolon

Fix these issues and while at it, fix some code style nitpicks as well:

  1) make the functions static as users are unlikely to export them

  2) include the relevant header

  3) Shorten the example a bit by removing a redundant variable
     definition

Fixes: 04ce9ab385dc ("async_xor: permit callers to pass in a 'dma/page scribble' region")
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Andre Noll <maan@tuebingen.mpg.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240529-async-dma-docs-v2-1-8faf87e72e6d@pengutronix.de

diff --git a/Documentation/crypto/async-tx-api.rst b/Documentation/crypto/async-tx-api.rst
index 27c146b54d713dcabfd307a689d7de6ed7443047..f88a7809385e25fed7eda51a56530905c1653a5b 100644 (file)
--- a/Documentation/crypto/async-tx-api.rst
+++ b/Documentation/crypto/async-tx-api.rst
@@ -150,38 +150,38 @@ of an operation.
 Perform a xor->copy->xor operation where each operation depends on the
 result from the previous operation::
 
-    void callback(void *param)
-    {
-           struct completion *cmp = param;
+    #include <linux/async_tx.h>
 
-           complete(cmp);
+    static void callback(void *param)
+    {
+           complete(param);
     }
 
-    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)
+    #define NDISKS  2
+
+    static void run_xor_copy_xor(struct page **xor_srcs,
+                                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, NDISKS, xor_len, &submit);
 
-           submit->depend_tx = tx;
+           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);
+           tx = async_xor(xor_dest, xor_srcs, 0, NDISKS, xor_len, &submit);
 
            async_tx_issue_pending_all();