async_tx: avoid the async xor_zero_sum path when src_cnt > device->max_xor

If the channel cannot perform the operation in one call to
->device_prep_dma_zero_sum, then fallback to the xor+page_is_zero path.
This only affects users with arrays larger than 16 devices on iop13xx or
32 devices on iop3xx.

Cc: <stable@kernel.org>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/crypto/async_tx/async_xor.c b/crypto/async_tx/async_xor.c
index 7a9db353f1986fca6a4d778dd1e05977ff0fb790..1c445c7bdab7af3695eda2c43d07ba8c6b8ebfc2 100644 (file)
--- a/crypto/async_tx/async_xor.c
+++ b/crypto/async_tx/async_xor.c
@@ -271,7 +271,7 @@ async_xor_zero_sum(struct page *dest, struct page **src_list,
 
        BUG_ON(src_cnt <= 1);
 
-       if (device) {
+       if (device && src_cnt <= device->max_xor) {
                dma_addr_t *dma_src = (dma_addr_t *) src_list;
                unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0;
                int i;