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Date: Mon, 5 Nov 2012 12:37:38 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Xi Wang <xi.wang@gmail.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: fix NULL checking in dma_pool_create()
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On Mon,  5 Nov 2012 01:46:36 -0500
Xi Wang <xi.wang@gmail.com> wrote:

> First, `dev' is dereferenced in dev_to_node(dev), suggesting that it
> must be non-null.  Later `dev' is checked against NULL, suggesting
> the opposite.  This patch adds a NULL check before its use.
> 
> ...
>
> @@ -159,7 +160,9 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev,
>  		return NULL;
>  	}
>  
> -	retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
> +	node = dev ? dev_to_node(dev) : -1;
> +
> +	retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, node);
>  	if (!retval)
>  		return retval;

Well, the dma_pool_create() kerneldoc does not describe dev==NULL to be
acceptable usage and given the lack of oops reports, we can assume that
no code is calling this function with dev==NULL.

So I think we can just remove the code which handles dev==NULL?

From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Mon, 5 Nov 2012 12:37:38 -0800
From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] mm: fix NULL checking in dma_pool_create()
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Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org

On Mon,  5 Nov 2012 01:46:36 -0500
Xi Wang <xi.wang@gmail.com> wrote:

> First, `dev' is dereferenced in dev_to_node(dev), suggesting that it
> must be non-null.  Later `dev' is checked against NULL, suggesting
> the opposite.  This patch adds a NULL check before its use.
> 
> ...
>
> @@ -159,7 +160,9 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev,
>  		return NULL;
>  	}
>  
> -	retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
> +	node = dev ? dev_to_node(dev) : -1;
> +
> +	retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, node);
>  	if (!retval)
>  		return retval;

Well, the dma_pool_create() kerneldoc does not describe dev==NULL to be
acceptable usage and given the lack of oops reports, we can assume that
no code is calling this function with dev==NULL.

So I think we can just remove the code which handles dev==NULL?

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