+ byteswap-dont-use-__builtin_bswap-with-sparse.patch added to -mm tree

+ byteswap-dont-use-__builtin_bswap-with-sparse.patch added to -mm tree

[akpm]

The patch titled
     Subject: byteswap: don't use __builtin_bswap*() with sparse
has been added to the -mm tree.  Its filename is
     byteswap-dont-use-__builtin_bswap-with-sparse.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/byteswap-dont-use-__builtin_bswap-with-sparse.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/byteswap-dont-use-__builtin_bswap-with-sparse.patch

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------------------------------------------------------
From: Johannes Berg <johannes.berg@intel.com>
Subject: byteswap: don't use __builtin_bswap*() with sparse

Although sparse declares __builtin_bswap*(), it can't actually do constant
folding inside them (yet).  As such, things like

  switch (protocol) {
  case htons(ETH_P_IP):
          break;
  }

which we do all over the place cause sparse to warn that it expects a
constant instead of a function call.

Disable __HAVE_BUILTIN_BSWAP*__ if __CHECKER__ is defined to
avoid this.

Fixes: 7322dd755e7d ("byteswap: try to avoid __builtin_constant_p gcc bug")
Link: http://lkml.kernel.org/r/1470914102-26389-1-git-send-email-johannes@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/compiler-gcc.h |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff -puN include/linux/compiler-gcc.h~byteswap-dont-use-__builtin_bswap-with-sparse include/linux/compiler-gcc.h
--- a/include/linux/compiler-gcc.h~byteswap-dont-use-__builtin_bswap-with-sparse
+++ a/include/linux/compiler-gcc.h
@@ -242,7 +242,11 @@
  */
 #define asm_volatile_goto(x...)	do { asm goto(x); asm (""); } while (0)
 
-#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
+/*
+ * sparse (__CHECKER__) pretends to be gcc, but can't do constant
+ * folding in __builtin_bswap*() (yet), so don't set these for it.
+ */
+#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__)
 #if GCC_VERSION >= 40400
 #define __HAVE_BUILTIN_BSWAP32__
 #define __HAVE_BUILTIN_BSWAP64__
@@ -250,7 +254,7 @@
 #if GCC_VERSION >= 40800
 #define __HAVE_BUILTIN_BSWAP16__
 #endif
-#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
+#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */
 
 #if GCC_VERSION >= 50000
 #define KASAN_ABI_VERSION 4
_

Patches currently in -mm which might be from johannes.berg@intel.com are

byteswap-dont-use-__builtin_bswap-with-sparse.patch