Re: [PATCH v2 1/2] iova: Remove some magazine pointer NULL checks

[Ethan Zhao]

John,

在 2022/9/5 17:11, John Garry 写道:
> Since commit 32e92d9f6f87 ("iommu/iova: Separate out rcache init") it
> has not been possible to have NULL CPU rcache "loaded" or "prev" magazine
> pointers. As such, the checks in iova_magazine_full(),
> iova_magazine_empty(), and iova_magazine_free_pfns() may be dropped.
>
> Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
> Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
> ---
>   drivers/iommu/iova.c | 7 ++-----
>   1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
> index 47d1983dfa2a..580fdf669922 100644
> --- a/drivers/iommu/iova.c
> +++ b/drivers/iommu/iova.c
> @@ -661,9 +661,6 @@ iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad)
>   	unsigned long flags;
>   	int i;
>   
> -	if (!mag)
> -		return;
> -

iommu_probe_device
  ops->probe_finalize(dev);
    intel_iommu_probe_finalize
       iommu_setup_dma_ops
         iommu_dma_init_domain(domain, dma_base, dma_limit, dev)
           iova_domain_init_rcaches
             {
             ...
             cpu_rcache->loaded = iova_magazine_alloc(GFP_KERNEL);
             cpu_rcache->prev = iova_magazine_alloc(GFP_KERNEL);
  	     if (!cpu_rcache->loaded || !cpu_rcache->prev) {
			    ret = -ENOMEM;
  		            goto out_err;

Do you mean iova_magazine_alloc() is impossible to fail ?

Thanks,

Ethan

>   	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
>   
>   	for (i = 0 ; i < mag->size; ++i) {
> @@ -683,12 +680,12 @@ iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad)
>   
>   static bool iova_magazine_full(struct iova_magazine *mag)
>   {
> -	return (mag && mag->size == IOVA_MAG_SIZE);
> +	return mag->size == IOVA_MAG_SIZE;
>   }
>   
>   static bool iova_magazine_empty(struct iova_magazine *mag)
>   {
> -	return (!mag || mag->size == 0);
> +	return mag->size == 0;
>   }
>   
>   static unsigned long iova_magazine_pop(struct iova_magazine *mag,

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