3 files changed, 22 insertions, 8 deletions

diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c
index ec87f53d5059..fdd8257d35d9 100644
--- a/crypto/async_tx/async_pq.c
+++ b/crypto/async_tx/async_pq.c
@@ -24,6 +24,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/raid/pq.h>
 #include <linux/async_tx.h>
+#include <linux/gfp.h>
 
 /**
  * pq_scribble_page - space to hold throwaway P or Q buffer for
diff --git a/crypto/async_tx/async_raid6_recov.c b/crypto/async_tx/async_raid6_recov.c
index 943f2abac9b4..ce038d861eb9 100644
--- a/crypto/async_tx/async_raid6_recov.c
+++ b/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_t bytes, int faila, int failb,
 
         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_t bytes, int faila,
 
         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++)
diff --git a/crypto/async_tx/raid6test.c b/crypto/async_tx/raid6test.c
index 3ec27c7e62ea..c1321935ebcc 100644
--- a/crypto/async_tx/raid6test.c
+++ b/crypto/async_tx/raid6test.c
@@ -20,6 +20,7 @@
  *
  */
 #include <linux/async_tx.h>
+#include <linux/gfp.h>
 #include <linux/random.h>
 
 #undef pr
@@ -214,6 +215,13 @@ static int raid6_test(void)
                 err += test(4, &tests);
         if (NDISKS > 5)
                 err += test(5, &tests);
+        /* the 11 and 12 disk cases are special for ioatdma (p-disabled
+         * q-continuation without extended descriptor)
+         */
+        if (NDISKS > 12) {
+                err += test(11, &tests);
+                err += test(12, &tests);
+        }
         err += test(NDISKS, &tests);
 
         pr("\n");