[PATCH] dmadev: fix structure alignment

[Wenwu Ma]

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: sta...@dpdk.org

Signed-off-by: Wenwu Ma <wenwux...@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