netdev - [PATCH] dma-debug: hns_enet_drv could use more DMA entries

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Date:   Thu, 29 Nov 2018 22:54:56 -0500
From:   Qian Cai <cai@....us>
To:     hch@....de, m.szyprowski@...sung.com, robin.murphy@....com
Cc:     yisen.zhuang@...wei.com, salil.mehta@...wei.com,
        iommu@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Qian Cai <cai@....us>
Subject: [PATCH] dma-debug: hns_enet_drv could use more DMA entries

The amount of DMA mappings from Hisilicon HNS ethernet devices is huge,
so it could trigger "DMA-API: debugging out of memory - disabling".

hnae_get_handle [1]
  hnae_init_queue
    hnae_init_ring
      hnae_alloc_buffers [2]
        debug_dma_map_page
          dma_entry_alloc

[1] for (i = 0; i < handle->q_num; i++)
[2] for (i = 0; i < ring->desc_num; i++)

On this Huawei TaiShan 2280 aarch64 server, it has reached the limit
already,

4 (ports) x 16 (handles) x 1024 (rings) = 65536

Signed-off-by: Qian Cai <cai@....us>
---
 kernel/dma/debug.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
index 231ca4628062..ae91689cc9ad 100644
--- a/kernel/dma/debug.c
+++ b/kernel/dma/debug.c
@@ -43,8 +43,13 @@
 
 /* allow architectures to override this if absolutely required */
 #ifndef PREALLOC_DMA_DEBUG_ENTRIES
+/* amount of DMA mappings on this driver is huge. */
+#ifdef	HNS_ENET
+#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 17)
+#else
 #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
 #endif
+#endif
 
 enum {
 	dma_debug_single,
-- 
2.17.2 (Apple Git-113)