linux-kernel - [PATCH 3/3] mm: stub out all of swapops.h for !CONFIG

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Date:   Wed,  3 Jul 2019 05:23:59 -0700
From:   Christoph Hellwig <hch@....de>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Arnd Bergmann <arnd@...db.de>, linux-riscv@...ts.infradead.org,
        linux-arch@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] mm: stub out all of swapops.h for !CONFIG_MMU

The whole header file deals with swap entries and PTEs, none of which
can exist for nommu builds.  The current nommu ports have lots of
stubs to allow the inline functions in swapops.h to compile, but
as none of this functionality is actually used there is no point
in even providing it.  This way we don't have to provide the stubs
for the upcoming RISC-V nommu port, and can eventually remove it
from the existing ports.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 include/linux/swapops.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 4d961668e5fc..b02922556846 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -6,6 +6,8 @@
 #include <linux/bug.h>
 #include <linux/mm_types.h>
 
+#ifdef CONFIG_MMU
+
 /*
  * swapcache pages are stored in the swapper_space radix tree.  We want to
  * get good packing density in that tree, so the index should be dense in
@@ -50,13 +52,11 @@ static inline pgoff_t swp_offset(swp_entry_t entry)
 	return entry.val & SWP_OFFSET_MASK;
 }
 
-#ifdef CONFIG_MMU
 /* check whether a pte points to a swap entry */
 static inline int is_swap_pte(pte_t pte)
 {
 	return !pte_none(pte) && !pte_present(pte);
 }
-#endif
 
 /*
  * Convert the arch-dependent pte representation of a swp_entry_t into an
@@ -375,4 +375,5 @@ static inline int non_swap_entry(swp_entry_t entry)
 }
 #endif
 
+#endif /* CONFIG_MMU */
 #endif /* _LINUX_SWAPOPS_H */
-- 
2.20.1