--- crypto/async_tx/async_raid6_recov.c

+++ crypto/async_tx/async_raid6_recov.c

@@ -324,6 +324,7 @@ struct dma_async_tx_descriptor *

async_raid6_2data_recov(int disks, size_t bytes, int faila, int failb,

struct page **blocks, struct async_submit_ctl *submit)

{

+ void *scribble = submit->scribble;

int non_zero_srcs, i;

BUG_ON(faila == failb);

@@ -332,11 +333,13 @@ async_raid6_2data_recov(int disks, size_

pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);

- /* we need to preserve the contents of 'blocks' for the async

- * case, so punt to synchronous if a scribble buffer is not available

+ /* if a dma resource is not available or a scribble buffer is not

+ * available punt to the synchronous path. In the 'dma not

+ * available' case be sure to use the scribble buffer to

+ * preserve the content of 'blocks' as the caller intended.

*/

- if (!submit->scribble) {

- void **ptrs = (void **) blocks;

+ if (!async_dma_find_channel(DMA_PQ) || !scribble) {

+ void **ptrs = scribble ? scribble : (void **) blocks;

async_tx_quiesce(&submit->depend_tx);

for (i = 0; i < disks; i++)

@@ -406,11 +409,13 @@ async_raid6_datap_recov(int disks, size_

pr_debug("%s: disks: %d len: %zu\n", __func__, disks, bytes);

- /* we need to preserve the contents of 'blocks' for the async

- * case, so punt to synchronous if a scribble buffer is not available

+ /* if a dma resource is not available or a scribble buffer is not

+ * available punt to the synchronous path. In the 'dma not

+ * available' case be sure to use the scribble buffer to

+ * preserve the content of 'blocks' as the caller intended.

*/

- if (!scribble) {

- void **ptrs = (void **) blocks;

+ if (!async_dma_find_channel(DMA_PQ) || !scribble) {

+ void **ptrs = scribble ? scribble : (void **) blocks;

async_tx_quiesce(&submit->depend_tx);

for (i = 0; i < disks; i++)