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[PATCH] dma-coherent: fix rmem_dma_device_init regression

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  [PATCH] dma-coherent: fix rmem_dma_device_init regression Arnd Bergmann <arnd@arndb.de> - 2017-09-15 17:10 +0200
    Re: [PATCH] dma-coherent: fix rmem_dma_device_init regression Roy Pledge <roy.pledge@nxp.com> - 2017-09-17 14:40 +0200
    Re: [PATCH] dma-coherent: fix rmem_dma_device_init regression Christoph Hellwig <hch@lst.de> - 2017-09-17 17:30 +0200

#1732921 — [PATCH] dma-coherent: fix rmem_dma_device_init regression

My recent bug fix introduced another bug, which caused rmem_dma_device_init
to always fail, as rmem->priv is never set to anything.

This restores the previous behavior, calling dma_init_coherent_memory()
whenever ->priv is NULL.

Fixes: d35b0996fef3 ("dma-coherent: fix dma_declare_coherent_memory() logic error")
Reported-by: Roy Pledge <roy.pledge@nxp.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
Roy, can you test this new fix?
---
 drivers/base/dma-coherent.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index a39b2166b145..744f64f43454 100644
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -348,16 +348,15 @@ static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
 	struct dma_coherent_mem *mem = rmem->priv;
 	int ret;
 
-	if (!mem)
-		return -ENODEV;
-
-	ret = dma_init_coherent_memory(rmem->base, rmem->base, rmem->size,
-				       DMA_MEMORY_EXCLUSIVE, &mem);
-
-	if (ret) {
-		pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
-			&rmem->base, (unsigned long)rmem->size / SZ_1M);
-		return ret;
+	if (!mem) {
+		ret = dma_init_coherent_memory(rmem->base, rmem->base,
+					       rmem->size,
+					       DMA_MEMORY_EXCLUSIVE, &mem);
+		if (ret) {
+			pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
+				&rmem->base, (unsigned long)rmem->size / SZ_1M);
+			return ret;
+		}
 	}
 	mem->use_dev_dma_pfn_offset = true;
 	rmem->priv = mem;
-- 
2.9.0

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#1733444

On 9/15/2017 11:08 AM, Arnd Bergmann wrote:
> My recent bug fix introduced another bug, which caused rmem_dma_device_init
> to always fail, as rmem->priv is never set to anything.
> 
> This restores the previous behavior, calling dma_init_coherent_memory()
> whenever ->priv is NULL.
> 
> Fixes: d35b0996fef3 ("dma-coherent: fix dma_declare_coherent_memory() logic error")
> Reported-by: Roy Pledge <roy.pledge@nxp.com>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> Roy, can you test this new fix?
> ---
>   drivers/base/dma-coherent.c | 19 +++++++++----------
>   1 file changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
> index a39b2166b145..744f64f43454 100644
> --- a/drivers/base/dma-coherent.c
> +++ b/drivers/base/dma-coherent.c
> @@ -348,16 +348,15 @@ static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
>   	struct dma_coherent_mem *mem = rmem->priv;
>   	int ret;
>   
> -	if (!mem)
> -		return -ENODEV;
> -
> -	ret = dma_init_coherent_memory(rmem->base, rmem->base, rmem->size,
> -				       DMA_MEMORY_EXCLUSIVE, &mem);
> -
> -	if (ret) {
> -		pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
> -			&rmem->base, (unsigned long)rmem->size / SZ_1M);
> -		return ret;
> +	if (!mem) {
> +		ret = dma_init_coherent_memory(rmem->base, rmem->base,
> +					       rmem->size,
> +					       DMA_MEMORY_EXCLUSIVE, &mem);
> +		if (ret) {
> +			pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
> +				&rmem->base, (unsigned long)rmem->size / SZ_1M);
> +			return ret;
> +		}
>   	}
>   	mem->use_dev_dma_pfn_offset = true;
>   	rmem->priv = mem;
> 
I tried this and it solves the issue I was seeing. Thanks for the quick fix.

Tested-by:  Roy Pledge <roy.pledge@nxp.com>

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#1733480

Thanks a lot Arnd,

applied to the dma-mapping tree for 4.14.

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