From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:58514 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751413AbdGRPQA (ORCPT ); Tue, 18 Jul 2017 11:16:00 -0400 Subject: Patch "compiler, clang: always inline when CONFIG_OPTIMIZE_INLINING is disabled" has been added to the 4.12-stable tree To: rientjes@google.com, akpm@linux-foundation.org, catalin.marinas@arm.com, gregkh@linuxfoundation.org, mark.rutland@arm.com, mingo@kernel.org, mka@chromium.org, peterz@infradead.org, psodagud@codeaurora.org, torvalds@linux-foundation.org, will.deacon@arm.com Cc: , From: Date: Tue, 18 Jul 2017 17:15:51 +0200 Message-ID: <1500390951218255@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled compiler, clang: always inline when CONFIG_OPTIMIZE_INLINING is disabled to the 4.12-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: compiler-clang-always-inline-when-config_optimize_inlining-is-disabled.patch and it can be found in the queue-4.12 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 9a04dbcfb33b4012d0ce8c0282f1e3ca694675b1 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Thu, 6 Jul 2017 15:35:24 -0700 Subject: compiler, clang: always inline when CONFIG_OPTIMIZE_INLINING is disabled From: David Rientjes commit 9a04dbcfb33b4012d0ce8c0282f1e3ca694675b1 upstream. The motivation for commit abb2ea7dfd82 ("compiler, clang: suppress warning for unused static inline functions") was to suppress clang's warnings about unused static inline functions. For configs without CONFIG_OPTIMIZE_INLINING enabled, such as any non-x86 architecture, `inline' in the kernel implies that __attribute__((always_inline)) is used. Some code depends on that behavior, see https://lkml.org/lkml/2017/6/13/918: net/built-in.o: In function `__xchg_mb': arch/arm64/include/asm/cmpxchg.h:99: undefined reference to `__compiletime_assert_99' arch/arm64/include/asm/cmpxchg.h:99: undefined reference to `__compiletime_assert_99 The full fix would be to identify these breakages and annotate the functions with __always_inline instead of `inline'. But since we are late in the 4.12-rc cycle, simply carry forward the forced inlining behavior and work toward moving arm64, and other architectures, toward CONFIG_OPTIMIZE_INLINING behavior. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1706261552200.1075@chino.kir.corp.google.com Signed-off-by: David Rientjes Reported-by: Sodagudi Prasad Tested-by: Sodagudi Prasad Tested-by: Matthias Kaehlcke Cc: Mark Rutland Cc: Will Deacon Cc: Catalin Marinas Cc: Ingo Molnar Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- include/linux/compiler-clang.h | 8 -------- include/linux/compiler-gcc.h | 18 +++++++++++------- 2 files changed, 11 insertions(+), 15 deletions(-) --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -15,11 +15,3 @@ * with any version that can compile the kernel */ #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) - -/* - * GCC does not warn about unused static inline functions for - * -Wunused-function. This turns out to avoid the need for complex #ifdef - * directives. Suppress the warning in clang as well. - */ -#undef inline -#define inline inline __attribute__((unused)) notrace --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -66,18 +66,22 @@ /* * Force always-inline if the user requests it so via the .config, - * or if gcc is too old: + * or if gcc is too old. + * GCC does not warn about unused static inline functions for + * -Wunused-function. This turns out to avoid the need for complex #ifdef + * directives. Suppress the warning in clang as well by using "unused" + * function attribute, which is redundant but not harmful for gcc. */ #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) -#define inline inline __attribute__((always_inline)) notrace -#define __inline__ __inline__ __attribute__((always_inline)) notrace -#define __inline __inline __attribute__((always_inline)) notrace +#define inline inline __attribute__((always_inline,unused)) notrace +#define __inline__ __inline__ __attribute__((always_inline,unused)) notrace +#define __inline __inline __attribute__((always_inline,unused)) notrace #else /* A lot of inline functions can cause havoc with function tracing */ -#define inline inline notrace -#define __inline__ __inline__ notrace -#define __inline __inline notrace +#define inline inline __attribute__((unused)) notrace +#define __inline__ __inline__ __attribute__((unused)) notrace +#define __inline __inline __attribute__((unused)) notrace #endif #define __always_inline inline __attribute__((always_inline)) Patches currently in stable-queue which might be from rientjes@google.com are queue-4.12/compiler-clang-always-inline-when-config_optimize_inlining-is-disabled.patch