LinuxKPI: move clear_page() within the linux/page.h file

clear_page() would normally live in asm/page.h but adding the file
and fixing the dependencies would be too much for a single line.

Move the function to the end of the file with a clear separator
and make it clear that it does not operate on a 'struct page'
but on a page address by changing the argument name and leaving
a comment.

The function is currently used by at least mthca(4) as the only
in-tree consumer, and drm-kmod ttm_pool.c.

No functional changes.

Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
Reviewed by:	emaste
Differential Revision: https://reviews.freebsd.org/D58296

1 files changed, 7 insertions, 1 deletions

diff --git a/sys/compat/linuxkpi/common/include/linux/page.h b/sys/compat/linuxkpi/common/include/linux/page.h
index 6f5f37d2fd0f..a8e266af95fd 100644
--- a/sys/compat/linuxkpi/common/include/linux/page.h
+++ b/sys/compat/linuxkpi/common/include/linux/page.h
@@ -79,7 +79,6 @@ pgprot2cachemode(pgprot_t prot)
 #define	nth_page(page,n)	pfn_to_page(page_to_pfn(page) + (n))
 #define	page_to_phys(page)	VM_PAGE_TO_PHYS(page)
 
-#define	clear_page(page)		memset(page, 0, PAGE_SIZE)
 #define	pgprot_noncached(prot)		\
 	(((prot) & VM_PROT_ALL) | cachemode2protval(VM_MEMATTR_UNCACHEABLE))
 #ifdef VM_MEMATTR_WRITE_COMBINING
@@ -129,4 +128,11 @@ clflush_cache_range(void *addr, unsigned int size)
 
 int lkpi_set_pages_attr(struct page *page, int numpages, vm_memattr_t ma);
 
+/* -------------------------------------------------------------------------- */
+/*
+ * clear_page() is called on kmem allocated page addresses, thus zeros a page
+ * not a 'struct page'.  Really belongs into <asm/page.h>.
+ */
+#define	clear_page(_pa)		memset(_pa, 0, PAGE_SIZE)
+
 #endif	/* _LINUXKPI_LINUX_PAGE_H_ */