linux-kernel - Re: [PATCHv4 3/5] common: dma-mapping: Introduce common remapping functions

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Date:	Wed, 23 Jul 2014 12:16:09 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Laura Abbott <lauraa@...eaurora.org>
Cc:	Will Deacon <Will.Deacon@....com>,
	David Riley <davidriley@...omium.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Ritesh Harjain <ritesh.harjani@...il.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Russell King <linux@....linux.org.uk>,
	Thierry Reding <thierry.reding@...il.com>,
	Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCHv4 3/5] common: dma-mapping: Introduce common remapping
 functions

On Wed, Jul 23, 2014 at 02:35:06AM +0100, Laura Abbott wrote:
> +void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags)
> +{
> +	struct vm_struct *area = find_vm_area(cpu_addr);
> +
> +	if (!area || (area->flags & vm_flags) != vm_flags) {
> +		WARN(1, "trying to free invalid coherent area: %p\n", cpu_addr);
> +		return;
> +	}
> +
> +	unmap_kernel_range((unsigned long)cpu_addr, size);
> +	vunmap(cpu_addr);
> +}

One more thing - is unmap_kernel_range() needed here? vunmap() ends up
calling vunmap_page_range(), same as unmap_kernel_range(). I think one
difference is that in the vunmap case, TLB flushing is done lazily.

-- 
Catalin
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