Messages in this thread Patch in this message | | | Date | Fri, 8 May 2015 12:50:55 +0200 | From | Ingo Molnar <> | Subject | [PATCH] x86/mm: Clean up types in xlate_dev_mem_ptr() some more |
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> Ugh, I pulled, but: > > On Wed, May 6, 2015 at 5:58 AM, Ingo Molnar <mingo2.kernel.org@gmail.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.
Yeah, not sure why I didn't notice that, I love void * arithmetics.
> So the cleanup to use "start/offset" is a good cleanup, but you > should have kept "addr" as a pointer.
Something like the patch below?
Thanks,
Ingo
===================> From 562bfca4c80175d1d18eef5c3f4bb8dda53c03e4 Mon Sep 17 00:00:00 2001 From: Ingo Molnar <mingo@kernel.org> Date: Fri, 8 May 2015 12:43:53 +0200 Subject: [PATCH] x86/mm: Clean up types in xlate_dev_mem_ptr() some more
So Linus noticed that in:
94d4b4765b7d ("x86/mm: Clean up types in xlate_dev_mem_ptr()")
... I added two nonsensical casts, due to the poor type choice for 'vaddr'.
Change it to 'void *' and take advantage of void * arithmetics.
This removes the casts.
( Also remove a nonsensical return line from unxlate_dev_mem_ptr() while at it. )
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> --- arch/x86/mm/ioremap.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index 70e7444c6835..27ff21216dfa 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -353,18 +353,18 @@ void *xlate_dev_mem_ptr(phys_addr_t phys) { unsigned long start = phys & PAGE_MASK; unsigned long offset = phys & ~PAGE_MASK; - unsigned long vaddr; + void *vaddr; /* If page is RAM, we can use __va. Otherwise ioremap and unmap. */ if (page_is_ram(start >> PAGE_SHIFT)) return __va(phys); - vaddr = (unsigned long)ioremap_cache(start, PAGE_SIZE); + vaddr = 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; + return vaddr; } void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr) @@ -373,7 +373,6 @@ void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr) return; iounmap((void __iomem *)((unsigned long)addr & PAGE_MASK)); - return; } static pte_t bm_pte[PAGE_SIZE/sizeof(pte_t)] __page_aligned_bss;
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