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byteswap: don't use __builtin_bswap*() with sparse

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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: 7322dd755e ("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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Berg 2016-08-25 15:16:45 -07:00 committed by Linus Torvalds
parent 61c04572de
commit 101b29a204
1 changed files with 6 additions and 2 deletions
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8
include/linux/compiler-gcc.h
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@ -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