linux-kernel - Re: [PATCH] iommu/vt-d: Use bitmap

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Date:   Sat, 18 Dec 2021 13:56:09 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        dwmw2@...radead.org, joro@...tes.org, will@...nel.org
Cc:     baolu.lu@...ux.intel.com, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] iommu/vt-d: Use bitmap_zalloc() when applicable

On 2021/12/18 5:58, Christophe JAILLET wrote:
> 'ommu->domain_ids' is a bitmap. So use 'bitmap_zalloc()' to simplify
> code and improve the semantic, instead of hand writing it.
> 
> Also change the corresponding 'kfree()' into 'bitmap_free()' to keep
> consistency.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
>   drivers/iommu/intel/iommu.c | 9 ++++-----
>   1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index b6a8f3282411..4acc97765209 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -1878,17 +1878,16 @@ static void iommu_disable_translation(struct intel_iommu *iommu)
>   
>   static int iommu_init_domains(struct intel_iommu *iommu)
>   {
> -	u32 ndomains, nlongs;
> +	u32 ndomains;
>   	size_t size;
>   
>   	ndomains = cap_ndoms(iommu->cap);
>   	pr_debug("%s: Number of Domains supported <%d>\n",
>   		 iommu->name, ndomains);
> -	nlongs = BITS_TO_LONGS(ndomains);
>   
>   	spin_lock_init(&iommu->lock);
>   
> -	iommu->domain_ids = kcalloc(nlongs, sizeof(unsigned long), GFP_KERNEL);
> +	iommu->domain_ids = bitmap_zalloc(ndomains, GFP_KERNEL);
>   	if (!iommu->domain_ids)
>   		return -ENOMEM;
>   
> @@ -1903,7 +1902,7 @@ static int iommu_init_domains(struct intel_iommu *iommu)
>   	if (!iommu->domains || !iommu->domains[0]) {
>   		pr_err("%s: Allocating domain array failed\n",
>   		       iommu->name);
> -		kfree(iommu->domain_ids);
> +		bitmap_free(iommu->domain_ids);
>   		kfree(iommu->domains);
>   		iommu->domain_ids = NULL;
>   		iommu->domains    = NULL;
> @@ -1964,7 +1963,7 @@ static void free_dmar_iommu(struct intel_iommu *iommu)
>   		for (i = 0; i < elems; i++)
>   			kfree(iommu->domains[i]);
>   		kfree(iommu->domains);
> -		kfree(iommu->domain_ids);
> +		bitmap_free(iommu->domain_ids);
>   		iommu->domains = NULL;
>   		iommu->domain_ids = NULL;
>   	}

This patch has been merged to Joerg's tree through

https://lore.kernel.org/linux-iommu/20211217083817.1745419-2-baolu.lu@linux.intel.com/

Are there any extra changes in this one?

Best regards,
baolu