[PATCH] dmadev: fix structure alignment

[Wenwu Ma <wenwux.ma@intel.com>]

The structure rte_dma_dev needs cacheline alignment, but the return
value of malloc may not be aligned to the cacheline. Therefore,
extra memory is applied for realignment.

Fixes: b36970f2e13e ("dmadev: introduce DMA device library")
Cc: stable@dpdk.org

Signed-off-by: Wenwu Ma <wenwux.ma@intel.com>
---
 lib/dmadev/rte_dmadev.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/lib/dmadev/rte_dmadev.c b/lib/dmadev/rte_dmadev.c
index 5953a77bd6..61e106d574 100644
--- a/lib/dmadev/rte_dmadev.c
+++ b/lib/dmadev/rte_dmadev.c
@@ -160,15 +160,25 @@ static int
 dma_dev_data_prepare(void)
 {
 	size_t size;
+	void *ptr;
 
 	if (rte_dma_devices != NULL)
 		return 0;
 
-	size = dma_devices_max * sizeof(struct rte_dma_dev);
-	rte_dma_devices = malloc(size);
-	if (rte_dma_devices == NULL)
+	/* The dma device object is expected to align cacheline, but
+	 * the return value of malloc may not be aligned to the cache line.
+	 * Therefore, extra memory is applied for realignment.
+	 * note: We do not call posix_memalign/aligned_alloc because it is
+	 * version dependent on libc.
+	 */
+	size = dma_devices_max * sizeof(struct rte_dma_dev) +
+		RTE_CACHE_LINE_SIZE;
+	ptr = malloc(size);
+	if (ptr == NULL)
 		return -ENOMEM;
-	memset(rte_dma_devices, 0, size);
+	memset(ptr, 0, size);
+
+	rte_dma_devices = RTE_PTR_ALIGN(ptr, RTE_CACHE_LINE_SIZE);
 
 	return 0;
 }
-- 
2.25.1