x86/mm: Clean up types in xlate_dev_mem_ptr()

Pavel Machek reported the following compiler warning on
x86/32 CONFIG_HIGHMEM64G=y builds:

  arch/x86/mm/ioremap.c:344:10: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]

Clean up the types in this function by using a single natural type for
internal calculations (unsigned long), to make it more apparent what's
happening, and also to remove fragile casts.

Reported-by: Pavel Machek <pavel@ucw.cz>
Cc: jgross@suse.com
Cc: roland@purestorage.com
Link: http://lkml.kernel.org/r/20150416080440.GA507@amd
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index fdf617c00e2fecad500e4a58c5fc71fc801a105d..4bf037b20f47601d3d45ab7c62f73804a3def942 100644 (file)
--- 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)
 {
-       void *addr;
-       unsigned long start = phys & PAGE_MASK;
+       unsigned long start  = phys &  PAGE_MASK;
+       unsigned long offset = phys & ~PAGE_MASK;
+       unsigned long vaddr;
 
        /* If page is RAM, we can use __va. Otherwise ioremap and unmap. */
        if (page_is_ram(start >> PAGE_SHIFT))
                return __va(phys);
 
-       addr = (void __force *)ioremap_cache(start, PAGE_SIZE);
-       if (addr)
-               addr = (void *)((unsigned long)addr | (phys & ~PAGE_MASK));
+       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 addr;
+       return (void *)vaddr;
 }
 
 void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)