[PATCH] Check the argument of kunmap on architectures without highmem

[PATCH] Check the argument of kunmap on architectures without highmem

[Matthew Wilcox]

If you're using a non-highmem architecture, passing an argument
with the wrong type to kunmap() doesn't give you a warning because the
ifdef doesn't check the type.

Using a static inline function solves the problem nicely.

Reported-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 1fcb712..211ff44 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -55,7 +55,9 @@ static inline void *kmap(struct page *page)
 	return page_address(page);
 }
 
-#define kunmap(page) do { (void) (page); } while (0)
+static inline void kunmap(struct page *page)
+{
+}
 
 static inline void *kmap_atomic(struct page *page, enum km_type idx)
 {

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."