linux-kernel - Re: [PATCH] x86: dma-mapping: Fix arch_dma_alloc

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Date:	Sun, 25 Oct 2015 23:46:56 +0200 (EET)
From:	Meelis Roos <mroos@...ux.ee>
To:	Ville Syrjälä <ville.syrjala@...ux.intel.com>
cc:	Linux Kernel list <linux-kernel@...r.kernel.org>,
	Christoph Hellwig <hch@....de>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] x86: dma-mapping: Fix arch_dma_alloc_attrs() oops with
 NULL dev

> From: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> 
> Commit 6894258eda2f ("dma-mapping: consolidate dma_{alloc,free}_{attrs,coherent}")
> broke drivers that pass NULL as the device for dma_alloc.
> Fix things by moving the ISA DMA fallback dev assignment earlier.
> 
> A quick search suggest that Meelis Roos has hit this with sb16, and I
> caught it with smsc-ircc2. Here's the oops I got:
[...]

The patch also fixes my SB16 issue, thank you!

> diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
> index 1b55de1..cd99433 100644
> --- a/arch/x86/kernel/pci-dma.c
> +++ b/arch/x86/kernel/pci-dma.c
> @@ -131,11 +131,12 @@ void dma_generic_free_coherent(struct device *dev, size_t size, void *vaddr,
>  
>  bool arch_dma_alloc_attrs(struct device **dev, gfp_t *gfp)
>  {
> +	if (!*dev)
> +		*dev = &x86_dma_fallback_dev;
> +
>  	*gfp &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
>  	*gfp = dma_alloc_coherent_gfp_flags(*dev, *gfp);
>  
> -	if (!*dev)
> -		*dev = &x86_dma_fallback_dev;
>  	if (!is_device_dma_capable(*dev))
>  		return false;
>  	return true;
> 

-- 
Meelis Roos (mroos@...ux.ee)
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