linux-kernel - Re: [PATCH 1/4] mm: introduce vma_set

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Date:   Thu, 8 Oct 2020 14:06:33 +0200
From:   Christian König <ckoenig.leichtzumerken@...il.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linaro-mm-sig@...ts.linaro.org, dri-devel@...ts.freedesktop.org,
        linux-media@...r.kernel.org, chris@...is-wilson.co.uk,
        airlied@...hat.com, akpm@...ux-foundation.org, daniel@...ll.ch,
        sumit.semwal@...aro.org
Subject: Re: [PATCH 1/4] mm: introduce vma_set_file function v2

Am 08.10.20 um 13:39 schrieb Matthew Wilcox:
> On Thu, Oct 08, 2020 at 01:23:39PM +0200, Christian König wrote:
>>   drivers/dma-buf/dma-buf.c                  | 16 +++++-----------
>>   drivers/gpu/drm/etnaviv/etnaviv_gem.c      |  4 +---
>>   drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c |  3 +--
>>   drivers/gpu/drm/i915/gem/i915_gem_mman.c   |  4 ++--
>>   drivers/gpu/drm/msm/msm_gem.c              |  4 +---
>>   drivers/gpu/drm/omapdrm/omap_gem.c         |  3 +--
>>   drivers/gpu/drm/vgem/vgem_drv.c            |  3 +--
>>   drivers/staging/android/ashmem.c           |  5 ++---
> ...
>> +++ b/mm/mmap.c
>> @@ -136,6 +136,22 @@ void vma_set_page_prot(struct vm_area_struct *vma)
>>   	WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
>>   }
>>   
>> +/*
>> + * Change backing file, only valid to use during initial VMA setup.
>> + */
>> +struct file *vma_set_file(struct vm_area_struct *vma, struct file *file)
>> +{
>> +	if (file)
>> +	        get_file(file);
>> +
>> +	swap(vma->vm_file, file);
>> +
>> +	if (file)
>> +		fput(file);
>> +
>> +	return file;
>> +}
>> +
> These users are all potentially modules.  You need an EXPORT_SYMBOL()?

Oh, good point. Yeah I totally missed that. The initial DMA-buf use case 
was not inside a module.

Thanks,
Christian.