linux-kernel - Re: [PATCH 1/7] iommu/iova: fix incorrect variable types

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Message-ID: <5fd3cc4b-44c1-e300-6254-892a6dfa435c@arm.com>
Date:   Thu, 23 Mar 2017 11:42:56 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Zhen Lei <thunder.leizhen@...wei.com>,
        Joerg Roedel <joro@...tes.org>,
        iommu <iommu@...ts.linux-foundation.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Sudeep Dutt <sudeep.dutt@...el.com>,
        Ashutosh Dixit <ashutosh.dixit@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Cc:     Zefan Li <lizefan@...wei.com>, Xinwei Hu <huxinwei@...wei.com>,
        Tianhong Ding <dingtianhong@...wei.com>,
        Hanjun Guo <guohanjun@...wei.com>
Subject: Re: [PATCH 1/7] iommu/iova: fix incorrect variable types

On 22/03/17 06:27, Zhen Lei wrote:
> Keep these four variables type consistent with the paramters of function
> __alloc_and_insert_iova_range and the members of struct iova:
> 
> 1. static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
> 		unsigned long size, unsigned long limit_pfn,
> 
> 2. struct iova {
> 	unsigned long	pfn_hi;
> 	unsigned long	pfn_lo;
> 
> In fact, limit_pfn is most likely larger than 32 bits on DMA64.

FWIW if pad_size manages to overflow an int something's probably gone
horribly wrong, but there's no harm in making it consistent with
everything else here. However, given that patch #6 makes this irrelevant
anyway, do we really need to bother?

Robin.

> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
> ---
>  drivers/iommu/iova.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
> index b7268a1..8ba8b496 100644
> --- a/drivers/iommu/iova.c
> +++ b/drivers/iommu/iova.c
> @@ -104,8 +104,8 @@ __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
>   * Computes the padding size required, to make the start address
>   * naturally aligned on the power-of-two order of its size
>   */
> -static unsigned int
> -iova_get_pad_size(unsigned int size, unsigned int limit_pfn)
> +static unsigned long
> +iova_get_pad_size(unsigned long size, unsigned long limit_pfn)
>  {
>  	return (limit_pfn + 1 - size) & (__roundup_pow_of_two(size) - 1);
>  }
> @@ -117,7 +117,7 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
>  	struct rb_node *prev, *curr = NULL;
>  	unsigned long flags;
>  	unsigned long saved_pfn;
> -	unsigned int pad_size = 0;
> +	unsigned long pad_size = 0;
>  
>  	/* Walk the tree backwards */
>  	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
>