Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754083AbbK3Nit (ORCPT ); Mon, 30 Nov 2015 08:38:49 -0500 Received: from mail.bmw-carit.de ([62.245.222.98]:46300 "EHLO linuxmail.bmw-carit.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753994AbbK3Nir (ORCPT ); Mon, 30 Nov 2015 08:38:47 -0500 From: Daniel Wagner To: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org Cc: Daniel Wagner , Thomas Gleixner , Peter Zijlstra , linux-kbuild@vger.kernel.org, Marcelo Tosatti , Paolo Bonzini , "Paul E. McKenney" , Paul Gortmaker , Steven Rostedt , Boqun Feng Subject: [PATCH tip v5 2/5] kbuild: Add option to turn incompatible pointer check into error Date: Mon, 30 Nov 2015 14:38:28 +0100 Message-Id: <1448890711-5812-3-git-send-email-daniel.wagner@bmw-carit.de> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1448890711-5812-1-git-send-email-daniel.wagner@bmw-carit.de> References: <1448890711-5812-1-git-send-email-daniel.wagner@bmw-carit.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2690 Lines: 70 With the introduction of the simple wait API we have two very similar APIs in the kernel. For example wake_up() and swake_up() is only one character away. Although the compiler will warn happily the wrong usage it keeps on going an even links the kernel. Thomas and Peter would rather like to see early missuses reported as error early on. In a first attempt we tried to wrap all swait and wait calls into a macro which has an compile time type assertion. The result was pretty ugly and wasn't able to catch all wrong usages. woken_wake_function(), autoremove_wake_function() and wake_bit_function() are assigned as function pointers. Wrapping them with a macro around is not possible. Prefixing them with '_' was also not a real option because there some users in the kernel which do use them as well. All in all this attempt looked to intrusive and too ugly. An alternative is to turn the pointer type check into an error which catches wrong type uses. Obviously not only the swait/wait ones. That isn't a bad thing either. Though for the beginning let's introduce it as options in the kernel hacking section. Signed-off-by: Daniel Wagner Cc: Thomas Gleixner Cc: Peter Zijlstra --- Makefile | 4 ++++ lib/Kconfig.debug | 7 +++++++ 2 files changed, 11 insertions(+) diff --git a/Makefile b/Makefile index 416660d..8817273 100644 --- a/Makefile +++ b/Makefile @@ -625,6 +625,10 @@ KBUILD_CFLAGS += $(call cc-option,-fno-reorder-blocks,) \ $(call cc-option,-fno-partial-inlining) endif +ifdef CONFIG_ENABLE_ERR_TYPE_CHECK +KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types) +endif + ifneq ($(CONFIG_FRAME_WARN),0) KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN}) endif diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index ab76b99..21c0193 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -194,6 +194,13 @@ config ENABLE_MUST_CHECK suppress the "warning: ignoring return value of 'foo', declared with attribute warn_unused_result" messages. +config ENABLE_ERR_TYPE_CHECK + bool "Turn pointer type check into an error" + default n + help + Instead of just warning that a wrong pointer type is used, + bail with a proper compile error. + config FRAME_WARN int "Warn for stack frames larger than (needs gcc 4.4)" range 0 8192 -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/