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Subject: Re: [PATCH 1/3] powerpc/64: __ioremap_at clean up in the error case
To: Nicholas Piggin <npiggin@gmail.com>, linuxppc-dev@lists.ozlabs.org
References: <20190610030818.17965-1-npiggin@gmail.com>
From: Christophe Leroy <christophe.leroy@c-s.fr>
Message-ID: <5d358284-c31c-5e01-240a-54b3491a8915@c-s.fr>
Date: Tue, 11 Jun 2019 08:28:06 +0200
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Le 10/06/2019 à 05:08, Nicholas Piggin a écrit :
> __ioremap_at error handling is wonky, it requires caller to clean up
> after it. Implement a helper that does the map and error cleanup and
> remove the requirement from the caller.
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> 
> This series is a different approach to the problem, using the generic
> ioremap_page_range directly which reduces added code, and moves
> the radix specific code into radix files. Thanks to Christophe for
> pointing out various problems with the previous patch.
> 
>   arch/powerpc/mm/pgtable_64.c | 27 ++++++++++++++++++++-------
>   1 file changed, 20 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
> index d2d976ff8a0e..6bd3660388aa 100644
> --- a/arch/powerpc/mm/pgtable_64.c
> +++ b/arch/powerpc/mm/pgtable_64.c
> @@ -108,14 +108,30 @@ unsigned long ioremap_bot;
>   unsigned long ioremap_bot = IOREMAP_BASE;
>   #endif
>   
> +static int ioremap_range(unsigned long ea, phys_addr_t pa, unsigned long size, pgprot_t prot, int nid)
> +{
> +	unsigned long i;
> +
> +	for (i = 0; i < size; i += PAGE_SIZE) {
> +		int err = map_kernel_page(ea + i, pa + i, prot);

Missing a blank line

> +		if (err) {

I'd have done the following to reduce indentation depth

		if (!err)
			continue

> +			if (slab_is_available())
> +				unmap_kernel_range(ea, size);

Shouldn't it be unmap_kernel_range(ea, i) ?

Christophe

> +			else
> +				WARN_ON_ONCE(1); /* Should clean up */
> +			return err;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>   /**
>    * __ioremap_at - Low level function to establish the page tables
>    *                for an IO mapping
>    */
>   void __iomem *__ioremap_at(phys_addr_t pa, void *ea, unsigned long size, pgprot_t prot)
>   {
> -	unsigned long i;
> -
>   	/* We don't support the 4K PFN hack with ioremap */
>   	if (pgprot_val(prot) & H_PAGE_4K_PFN)
>   		return NULL;
> @@ -129,9 +145,8 @@ void __iomem *__ioremap_at(phys_addr_t pa, void *ea, unsigned long size, pgprot_
>   	WARN_ON(((unsigned long)ea) & ~PAGE_MASK);
>   	WARN_ON(size & ~PAGE_MASK);
>   
> -	for (i = 0; i < size; i += PAGE_SIZE)
> -		if (map_kernel_page((unsigned long)ea + i, pa + i, prot))
> -			return NULL;
> +	if (ioremap_range((unsigned long)ea, pa, size, prot, NUMA_NO_NODE))
> +		return NULL;
>   
>   	return (void __iomem *)ea;
>   }
> @@ -182,8 +197,6 @@ void __iomem * __ioremap_caller(phys_addr_t addr, unsigned long size,
>   
>   		area->phys_addr = paligned;
>   		ret = __ioremap_at(paligned, area->addr, size, prot);
> -		if (!ret)
> -			vunmap(area->addr);
>   	} else {
>   		ret = __ioremap_at(paligned, (void *)ioremap_bot, size, prot);
>   		if (ret)
>