From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752398AbcHKLPO (ORCPT ); Thu, 11 Aug 2016 07:15:14 -0400 Received: from s3.sipsolutions.net ([5.9.151.49]:52177 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752011AbcHKLPM (ORCPT ); Thu, 11 Aug 2016 07:15:12 -0400 From: Johannes Berg To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Arnd Bergmann , linux-sparse@vger.kernel.org, Johannes Berg Subject: [PATCH] byteswap: don't use __builtin_bswap*() with sparse Date: Thu, 11 Aug 2016 13:15:02 +0200 Message-Id: <1470914102-26389-1-git-send-email-johannes@sipsolutions.net> X-Mailer: git-send-email 2.8.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Johannes Berg 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. Cc: Arnd Bergmann Fixes: 7322dd755e7d ("byteswap: try to avoid __builtin_constant_p gcc bug") Signed-off-by: Johannes Berg --- include/linux/compiler-gcc.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index e2949397c19b..8dbc8929a6a0 100644 --- a/include/linux/compiler-gcc.h +++ b/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 -- 2.8.1