linux-kernel - Re: [GIT PULL] x86 fixes

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Date:	Wed, 6 May 2015 11:14:28 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Ingo Molnar <mingo2.kernel.org@...il.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [GIT PULL] x86 fixes

Ugh, I pulled, but:

On Wed, May 6, 2015 at 5:58 AM, Ingo Molnar <mingo2.kernel.org@...il.com> wrote:
>
> Ingo Molnar (1):
>       x86/mm: Clean up types in xlate_dev_mem_ptr()
>
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> index fdf617c00e2f..4bf037b20f47 100644
> --- a/arch/x86/mm/ioremap.c
> +++ b/arch/x86/mm/ioremap.c
> @@ -332,18 +332,20 @@ EXPORT_SYMBOL(iounmap);
>   */
>  void *xlate_dev_mem_ptr(phys_addr_t phys)
>  {
> +       unsigned long start  = phys &  PAGE_MASK;
> +       unsigned long offset = phys & ~PAGE_MASK;
> +       unsigned long vaddr;

That "unsigned long vaddr" is just stupid and not a cleanup.

It causes two pointless casts:

> +       vaddr = (unsigned long)ioremap_cache(start, PAGE_SIZE);
> +       /* Only add the offset on success and return NULL if the ioremap() failed: */
> +       if (vaddr)
> +               vaddr += offset;
>
> +       return (void *)vaddr;

neither of which is helpful in the least. And the "vaddr += offset"
would work equally well in "void *", gcc is perfectly happy to treat
"void *" arithmetic as byte offsets, it's both documented and already
extensively used in the kernel.

So the cleanup to use "start/offset" is a good cleanup, but you should
have kept "addr" as a pointer.

                       Linus
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