linux-kernel - Re: [PATCH 02/13] amdgpu: don't initialize range->list in amdgpu_hmm_init

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Message-ID: <a4586f5c-0ae4-8cbd-65ff-dfe70d34f99b@amd.com>
Date:   Wed, 31 Jul 2019 13:25:06 +0000
From:   "Kuehling, Felix" <Felix.Kuehling@....com>
To:     Christoph Hellwig <hch@....de>,
        Jérôme Glisse <jglisse@...hat.com>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Ben Skeggs <bskeggs@...hat.com>
CC:     Ralph Campbell <rcampbell@...dia.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "nouveau@...ts.freedesktop.org" <nouveau@...ts.freedesktop.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 02/13] amdgpu: don't initialize range->list in
 amdgpu_hmm_init_range

On 2019-07-30 1:51 a.m., Christoph Hellwig wrote:
> The list is used to add the range to another list as an entry in the
> core hmm code, so there is no need to initialize it in a driver.

I've seen code that uses list_empty to check whether a list head has 
been added to a list or not. For that to work, the list head needs to be 
initialized, and it has to be removed with list_del_init. If HMM doesn't 
ever do that with range->list, then this patch is Reviewed-by: Felix 
Kuehling <Felix.Kuehling@....com>


>
> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c | 1 -
>   1 file changed, 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
> index b698b423b25d..60b9fc9561d7 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
> @@ -484,6 +484,5 @@ void amdgpu_hmm_init_range(struct hmm_range *range)
>   		range->flags = hmm_range_flags;
>   		range->values = hmm_range_values;
>   		range->pfn_shift = PAGE_SHIFT;
> -		INIT_LIST_HEAD(&range->list);
>   	}
>   }