From patchwork Thu Oct 12 14:26:15 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 115637 Delivered-To: patch@linaro.org Received: by 10.140.22.163 with SMTP id 32csp2003960qgn; Thu, 12 Oct 2017 07:26:57 -0700 (PDT) X-Google-Smtp-Source: AOwi7QA3KzaqKypDRPoYzi7JrBf9dUQt5r9INUXDhhpd8mFIYKcXVT4F2TZQjbganCYmrqhbQb+3 X-Received: by 10.99.123.22 with SMTP id w22mr393411pgc.396.1507818417204; Thu, 12 Oct 2017 07:26:57 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1507818417; cv=none; d=google.com; s=arc-20160816; b=yKUs+//kteR85nfRRc2C1LkzJkdzrhIt5WSy7qVwBsKOmk3877nuGNiw12Nprj6JwP Cb5Wg7r1wWs+ypppQTmtbA/xp2HNyY3yGZOHNPX5ZTSLd9koBQXeFb4DKO0oJCoZZxX8 cpZ1t7RH0Df/wS3m2Z7KAjm8hTpSPKSk2maVWEQzpiS/6UL9ejSXQMzZ+nL5Ymk9v8kd 13j4ESp9T/vpsQVvicso/px+qvpVmuH4b9vMhArVeisD7l6nMtnNqMz8owueStB+6wEH MzJLxBUXiEbeueyZxGCWCAcBIbCYr54kjalKrhMln7rbNuqy7BZ7FouiiZqe4V7iHUtP hO+g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=jgDaMA/3ebdk1LGz2OZzDcVHi20mVSreF8+8KqXBgSw=; b=nAiyOXYdlDscqYMWVRitvTQamWgCDUK/erEPTjTAGlPd0NA6GE4K+t2T/myfqigiiv Y1AnVznEdNsv99Ihcxie3Wf5h/Qc9Y1/U3FYaWzPpMWOV1hoqaVB/o8GQU5OEOqX6evB fC5UUSf0TlEHbVrBTy/evmoMbCVk4JTUI6LzhcWDyYYoCw0HCiyI7NSXJ8lEp4ed9wa0 kI7CUGrIi+XE08kqft2fgX1zRTt1tu9Qr4ISURtilotb+IEgEeWnHLSC3X14VzvLgDnZ 242ToWX8kEbrxfwES0EUL5eiRGFfhAXQ4k5nGbiPDpWnfGyBetBuuf9kEqKKGV6WEY2T 6+Yg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id o128si53132pfg.292.2017.10.12.07.26.56; Thu, 12 Oct 2017 07:26:57 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752813AbdJLO0n (ORCPT + 27 others); Thu, 12 Oct 2017 10:26:43 -0400 Received: from foss.arm.com ([217.140.101.70]:47886 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752169AbdJLO0P (ORCPT ); Thu, 12 Oct 2017 10:26:15 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0EDEE15BE; Thu, 12 Oct 2017 07:26:15 -0700 (PDT) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id B118D3F483; Thu, 12 Oct 2017 07:26:14 -0700 (PDT) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id 645801AE1952; Thu, 12 Oct 2017 15:26:18 +0100 (BST) From: Will Deacon To: paulmck@linux.vnet.ibm.com Cc: linux-kernel@vger.kernel.org, mcree@orcon.net.nz, peterz@infradead.org, rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, linux-alpha@vger.kernel.org, Will Deacon Subject: [PATCH 1/3] linux/compiler.h: Split into compiler.h and compiler-types.h Date: Thu, 12 Oct 2017 15:26:15 +0100 Message-Id: <1507818377-7546-2-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1507818377-7546-1-git-send-email-will.deacon@arm.com> References: <1507818377-7546-1-git-send-email-will.deacon@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org linux/compiler.h is included indirectly by linux/types.h via uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h -> uapi/linux/stddef.h and is needed to provide a proper definition of offsetof. Unfortunately, compiler.h requires a definition of smp_read_barrier_depends() for defining lockless_dereference and soon for defining READ_ONCE, which means that all users of READ_ONCE will need to include asm/barrier.h to avoid splats such as: In file included from include/uapi/linux/stddef.h:1:0, from include/linux/stddef.h:4, from arch/h8300/kernel/asm-offsets.c:11: include/linux/list.h: In function 'list_empty': >> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration] smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ ^ A better alternative is to include asm/barrier.h in linux/compiler.h, but this requires a type definition for "bool" on some architectures (e.g. x86), which is defined later by linux/types.h. Type "bool" is also used directly in linux/compiler.h, so the whole thing is pretty fragile. This patch splits compiler.h in two: compiler-types.h contains type annotations, definitions and the compiler-specific parts, whereas compiler.h #includes compiler-types.h and additionally defines macros such as {READ,WRITE.ACCESS}_ONCE. uapi/linux/stddef.h and linux/linkage.h are then moved over to include linux/compiler-types.h, which fixes the build for h8 and blackfin. Reported-by: kbuild test robot Signed-off-by: Will Deacon --- arch/arm/include/asm/ptrace.h | 3 +- include/linux/compiler-clang.h | 2 +- include/linux/compiler-gcc.h | 2 +- include/linux/compiler-intel.h | 2 +- include/linux/compiler-types.h | 274 +++++++++++++++++++++++++++++++++++++++++ include/linux/compiler.h | 265 +-------------------------------------- include/linux/linkage.h | 2 +- include/uapi/linux/stddef.h | 2 +- scripts/headers_install.sh | 2 +- 9 files changed, 284 insertions(+), 270 deletions(-) create mode 100644 include/linux/compiler-types.h -- 2.1.4 diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h index e9c9a117bd25..c7cdbb43ae7c 100644 --- a/arch/arm/include/asm/ptrace.h +++ b/arch/arm/include/asm/ptrace.h @@ -126,8 +126,7 @@ extern unsigned long profile_pc(struct pt_regs *regs); /* * kprobe-based event tracer support */ -#include -#include +#include #define MAX_REG_OFFSET (offsetof(struct pt_regs, ARM_ORIG_r0)) extern int regs_query_register_offset(const char *name); diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index de179993e039..5947a3e6c0e6 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -1,4 +1,4 @@ -#ifndef __LINUX_COMPILER_H +#ifndef __LINUX_COMPILER_TYPES_H #error "Please don't include directly, include instead." #endif diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 16d41de92ee3..ce8e965646ef 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -1,4 +1,4 @@ -#ifndef __LINUX_COMPILER_H +#ifndef __LINUX_COMPILER_TYPES_H #error "Please don't include directly, include instead." #endif diff --git a/include/linux/compiler-intel.h b/include/linux/compiler-intel.h index d4c71132d07f..e438ac89c692 100644 --- a/include/linux/compiler-intel.h +++ b/include/linux/compiler-intel.h @@ -1,4 +1,4 @@ -#ifndef __LINUX_COMPILER_H +#ifndef __LINUX_COMPILER_TYPES_H #error "Please don't include directly, include instead." #endif diff --git a/include/linux/compiler-types.h b/include/linux/compiler-types.h new file mode 100644 index 000000000000..6b79a9bba9a7 --- /dev/null +++ b/include/linux/compiler-types.h @@ -0,0 +1,274 @@ +#ifndef __LINUX_COMPILER_TYPES_H +#define __LINUX_COMPILER_TYPES_H + +#ifndef __ASSEMBLY__ + +#ifdef __CHECKER__ +# define __user __attribute__((noderef, address_space(1))) +# define __kernel __attribute__((address_space(0))) +# define __safe __attribute__((safe)) +# define __force __attribute__((force)) +# define __nocast __attribute__((nocast)) +# define __iomem __attribute__((noderef, address_space(2))) +# define __must_hold(x) __attribute__((context(x,1,1))) +# define __acquires(x) __attribute__((context(x,0,1))) +# define __releases(x) __attribute__((context(x,1,0))) +# define __acquire(x) __context__(x,1) +# define __release(x) __context__(x,-1) +# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0) +# define __percpu __attribute__((noderef, address_space(3))) +# define __rcu __attribute__((noderef, address_space(4))) +# define __private __attribute__((noderef)) +extern void __chk_user_ptr(const volatile void __user *); +extern void __chk_io_ptr(const volatile void __iomem *); +# define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member)) +#else /* __CHECKER__ */ +# ifdef STRUCTLEAK_PLUGIN +# define __user __attribute__((user)) +# else +# define __user +# endif +# define __kernel +# define __safe +# define __force +# define __nocast +# define __iomem +# define __chk_user_ptr(x) (void)0 +# define __chk_io_ptr(x) (void)0 +# define __builtin_warning(x, y...) (1) +# define __must_hold(x) +# define __acquires(x) +# define __releases(x) +# define __acquire(x) (void)0 +# define __release(x) (void)0 +# define __cond_lock(x,c) (c) +# define __percpu +# define __rcu +# define __private +# define ACCESS_PRIVATE(p, member) ((p)->member) +#endif /* __CHECKER__ */ + +/* Indirect macros required for expanded argument pasting, eg. __LINE__. */ +#define ___PASTE(a,b) a##b +#define __PASTE(a,b) ___PASTE(a,b) + +#ifdef __KERNEL__ + +#ifdef __GNUC__ +#include +#endif + +#if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__) +#define notrace __attribute__((hotpatch(0,0))) +#else +#define notrace __attribute__((no_instrument_function)) +#endif + +/* Intel compiler defines __GNUC__. So we will overwrite implementations + * coming from above header files here + */ +#ifdef __INTEL_COMPILER +# include +#endif + +/* Clang compiler defines __GNUC__. So we will overwrite implementations + * coming from above header files here + */ +#ifdef __clang__ +#include +#endif + +/* + * Generic compiler-dependent macros required for kernel + * build go below this comment. Actual compiler/compiler version + * specific implementations come from the above header files + */ + +struct ftrace_branch_data { + const char *func; + const char *file; + unsigned line; + union { + struct { + unsigned long correct; + unsigned long incorrect; + }; + struct { + unsigned long miss; + unsigned long hit; + }; + unsigned long miss_hit[2]; + }; +}; + +struct ftrace_likely_data { + struct ftrace_branch_data data; + unsigned long constant; +}; + +#endif /* __KERNEL__ */ + +#endif /* __ASSEMBLY__ */ + +#ifdef __KERNEL__ +/* + * Allow us to mark functions as 'deprecated' and have gcc emit a nice + * warning for each use, in hopes of speeding the functions removal. + * Usage is: + * int __deprecated foo(void) + */ +#ifndef __deprecated +# define __deprecated /* unimplemented */ +#endif + +#ifdef MODULE +#define __deprecated_for_modules __deprecated +#else +#define __deprecated_for_modules +#endif + +#ifndef __must_check +#define __must_check +#endif + +#ifndef CONFIG_ENABLE_MUST_CHECK +#undef __must_check +#define __must_check +#endif +#ifndef CONFIG_ENABLE_WARN_DEPRECATED +#undef __deprecated +#undef __deprecated_for_modules +#define __deprecated +#define __deprecated_for_modules +#endif + +#ifndef __malloc +#define __malloc +#endif + +/* + * Allow us to avoid 'defined but not used' warnings on functions and data, + * as well as force them to be emitted to the assembly file. + * + * As of gcc 3.4, static functions that are not marked with attribute((used)) + * may be elided from the assembly file. As of gcc 3.4, static data not so + * marked will not be elided, but this may change in a future gcc version. + * + * NOTE: Because distributions shipped with a backported unit-at-a-time + * compiler in gcc 3.3, we must define __used to be __attribute__((used)) + * for gcc >=3.3 instead of 3.4. + * + * In prior versions of gcc, such functions and data would be emitted, but + * would be warned about except with attribute((unused)). + * + * Mark functions that are referenced only in inline assembly as __used so + * the code is emitted even though it appears to be unreferenced. + */ +#ifndef __used +# define __used /* unimplemented */ +#endif + +#ifndef __maybe_unused +# define __maybe_unused /* unimplemented */ +#endif + +#ifndef __always_unused +# define __always_unused /* unimplemented */ +#endif + +#ifndef noinline +#define noinline +#endif + +/* + * Rather then using noinline to prevent stack consumption, use + * noinline_for_stack instead. For documentation reasons. + */ +#define noinline_for_stack noinline + +#ifndef __always_inline +#define __always_inline inline +#endif + +#endif /* __KERNEL__ */ + +/* + * From the GCC manual: + * + * Many functions do not examine any values except their arguments, + * and have no effects except the return value. Basically this is + * just slightly more strict class than the `pure' attribute above, + * since function is not allowed to read global memory. + * + * Note that a function that has pointer arguments and examines the + * data pointed to must _not_ be declared `const'. Likewise, a + * function that calls a non-`const' function usually must not be + * `const'. It does not make sense for a `const' function to return + * `void'. + */ +#ifndef __attribute_const__ +# define __attribute_const__ /* unimplemented */ +#endif + +#ifndef __designated_init +# define __designated_init +#endif + +#ifndef __latent_entropy +# define __latent_entropy +#endif + +#ifndef __randomize_layout +# define __randomize_layout __designated_init +#endif + +#ifndef __no_randomize_layout +# define __no_randomize_layout +#endif + +#ifndef randomized_struct_fields_start +# define randomized_struct_fields_start +# define randomized_struct_fields_end +#endif + +/* + * Tell gcc if a function is cold. The compiler will assume any path + * directly leading to the call is unlikely. + */ + +#ifndef __cold +#define __cold +#endif + +/* Simple shorthand for a section definition */ +#ifndef __section +# define __section(S) __attribute__ ((__section__(#S))) +#endif + +#ifndef __visible +#define __visible +#endif + +#ifndef __nostackprotector +# define __nostackprotector +#endif + +/* + * Assume alignment of return value. + */ +#ifndef __assume_aligned +#define __assume_aligned(a, ...) +#endif + + +/* Are two types/vars the same type (ignoring qualifiers)? */ +#ifndef __same_type +# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) +#endif + +/* Is this type a native word size -- useful for atomic operations */ +#ifndef __native_word +# define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) +#endif + +#endif /* __LINUX_COMPILER_TYPES_H */ diff --git a/include/linux/compiler.h b/include/linux/compiler.h index e95a2631e545..c714239f453f 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -1,111 +1,12 @@ #ifndef __LINUX_COMPILER_H #define __LINUX_COMPILER_H -#ifndef __ASSEMBLY__ +#include -#ifdef __CHECKER__ -# define __user __attribute__((noderef, address_space(1))) -# define __kernel __attribute__((address_space(0))) -# define __safe __attribute__((safe)) -# define __force __attribute__((force)) -# define __nocast __attribute__((nocast)) -# define __iomem __attribute__((noderef, address_space(2))) -# define __must_hold(x) __attribute__((context(x,1,1))) -# define __acquires(x) __attribute__((context(x,0,1))) -# define __releases(x) __attribute__((context(x,1,0))) -# define __acquire(x) __context__(x,1) -# define __release(x) __context__(x,-1) -# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0) -# define __percpu __attribute__((noderef, address_space(3))) -# define __rcu __attribute__((noderef, address_space(4))) -# define __private __attribute__((noderef)) -extern void __chk_user_ptr(const volatile void __user *); -extern void __chk_io_ptr(const volatile void __iomem *); -# define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member)) -#else /* __CHECKER__ */ -# ifdef STRUCTLEAK_PLUGIN -# define __user __attribute__((user)) -# else -# define __user -# endif -# define __kernel -# define __safe -# define __force -# define __nocast -# define __iomem -# define __chk_user_ptr(x) (void)0 -# define __chk_io_ptr(x) (void)0 -# define __builtin_warning(x, y...) (1) -# define __must_hold(x) -# define __acquires(x) -# define __releases(x) -# define __acquire(x) (void)0 -# define __release(x) (void)0 -# define __cond_lock(x,c) (c) -# define __percpu -# define __rcu -# define __private -# define ACCESS_PRIVATE(p, member) ((p)->member) -#endif /* __CHECKER__ */ - -/* Indirect macros required for expanded argument pasting, eg. __LINE__. */ -#define ___PASTE(a,b) a##b -#define __PASTE(a,b) ___PASTE(a,b) +#ifndef __ASSEMBLY__ #ifdef __KERNEL__ -#ifdef __GNUC__ -#include -#endif - -#if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__) -#define notrace __attribute__((hotpatch(0,0))) -#else -#define notrace __attribute__((no_instrument_function)) -#endif - -/* Intel compiler defines __GNUC__. So we will overwrite implementations - * coming from above header files here - */ -#ifdef __INTEL_COMPILER -# include -#endif - -/* Clang compiler defines __GNUC__. So we will overwrite implementations - * coming from above header files here - */ -#ifdef __clang__ -#include -#endif - -/* - * Generic compiler-dependent macros required for kernel - * build go below this comment. Actual compiler/compiler version - * specific implementations come from the above header files - */ - -struct ftrace_branch_data { - const char *func; - const char *file; - unsigned line; - union { - struct { - unsigned long correct; - unsigned long incorrect; - }; - struct { - unsigned long miss; - unsigned long hit; - }; - unsigned long miss_hit[2]; - }; -}; - -struct ftrace_likely_data { - struct ftrace_branch_data data; - unsigned long constant; -}; - /* * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code * to disable branch tracing on a per file basis. @@ -332,6 +233,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s * with an explicit memory barrier or atomic instruction that provides the * required ordering. */ +#include #define __READ_ONCE(x, check) \ ({ \ @@ -362,167 +264,6 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s #endif /* __ASSEMBLY__ */ -#ifdef __KERNEL__ -/* - * Allow us to mark functions as 'deprecated' and have gcc emit a nice - * warning for each use, in hopes of speeding the functions removal. - * Usage is: - * int __deprecated foo(void) - */ -#ifndef __deprecated -# define __deprecated /* unimplemented */ -#endif - -#ifdef MODULE -#define __deprecated_for_modules __deprecated -#else -#define __deprecated_for_modules -#endif - -#ifndef __must_check -#define __must_check -#endif - -#ifndef CONFIG_ENABLE_MUST_CHECK -#undef __must_check -#define __must_check -#endif -#ifndef CONFIG_ENABLE_WARN_DEPRECATED -#undef __deprecated -#undef __deprecated_for_modules -#define __deprecated -#define __deprecated_for_modules -#endif - -#ifndef __malloc -#define __malloc -#endif - -/* - * Allow us to avoid 'defined but not used' warnings on functions and data, - * as well as force them to be emitted to the assembly file. - * - * As of gcc 3.4, static functions that are not marked with attribute((used)) - * may be elided from the assembly file. As of gcc 3.4, static data not so - * marked will not be elided, but this may change in a future gcc version. - * - * NOTE: Because distributions shipped with a backported unit-at-a-time - * compiler in gcc 3.3, we must define __used to be __attribute__((used)) - * for gcc >=3.3 instead of 3.4. - * - * In prior versions of gcc, such functions and data would be emitted, but - * would be warned about except with attribute((unused)). - * - * Mark functions that are referenced only in inline assembly as __used so - * the code is emitted even though it appears to be unreferenced. - */ -#ifndef __used -# define __used /* unimplemented */ -#endif - -#ifndef __maybe_unused -# define __maybe_unused /* unimplemented */ -#endif - -#ifndef __always_unused -# define __always_unused /* unimplemented */ -#endif - -#ifndef noinline -#define noinline -#endif - -/* - * Rather then using noinline to prevent stack consumption, use - * noinline_for_stack instead. For documentation reasons. - */ -#define noinline_for_stack noinline - -#ifndef __always_inline -#define __always_inline inline -#endif - -#endif /* __KERNEL__ */ - -/* - * From the GCC manual: - * - * Many functions do not examine any values except their arguments, - * and have no effects except the return value. Basically this is - * just slightly more strict class than the `pure' attribute above, - * since function is not allowed to read global memory. - * - * Note that a function that has pointer arguments and examines the - * data pointed to must _not_ be declared `const'. Likewise, a - * function that calls a non-`const' function usually must not be - * `const'. It does not make sense for a `const' function to return - * `void'. - */ -#ifndef __attribute_const__ -# define __attribute_const__ /* unimplemented */ -#endif - -#ifndef __designated_init -# define __designated_init -#endif - -#ifndef __latent_entropy -# define __latent_entropy -#endif - -#ifndef __randomize_layout -# define __randomize_layout __designated_init -#endif - -#ifndef __no_randomize_layout -# define __no_randomize_layout -#endif - -#ifndef randomized_struct_fields_start -# define randomized_struct_fields_start -# define randomized_struct_fields_end -#endif - -/* - * Tell gcc if a function is cold. The compiler will assume any path - * directly leading to the call is unlikely. - */ - -#ifndef __cold -#define __cold -#endif - -/* Simple shorthand for a section definition */ -#ifndef __section -# define __section(S) __attribute__ ((__section__(#S))) -#endif - -#ifndef __visible -#define __visible -#endif - -#ifndef __nostackprotector -# define __nostackprotector -#endif - -/* - * Assume alignment of return value. - */ -#ifndef __assume_aligned -#define __assume_aligned(a, ...) -#endif - - -/* Are two types/vars the same type (ignoring qualifiers)? */ -#ifndef __same_type -# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) -#endif - -/* Is this type a native word size -- useful for atomic operations */ -#ifndef __native_word -# define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) -#endif - /* Compile time object size, -1 for unknown */ #ifndef __compiletime_object_size # define __compiletime_object_size(obj) -1 diff --git a/include/linux/linkage.h b/include/linux/linkage.h index a6a42dd02466..9599d13cea0c 100644 --- a/include/linux/linkage.h +++ b/include/linux/linkage.h @@ -1,7 +1,7 @@ #ifndef _LINUX_LINKAGE_H #define _LINUX_LINKAGE_H -#include +#include #include #include #include diff --git a/include/uapi/linux/stddef.h b/include/uapi/linux/stddef.h index 621fa8ac4425..1ec6a7867c46 100644 --- a/include/uapi/linux/stddef.h +++ b/include/uapi/linux/stddef.h @@ -1,4 +1,4 @@ -#include +#include #ifndef __always_inline #define __always_inline inline diff --git a/scripts/headers_install.sh b/scripts/headers_install.sh index fdebd66f8fc1..bbb7f3d35289 100755 --- a/scripts/headers_install.sh +++ b/scripts/headers_install.sh @@ -33,7 +33,7 @@ do sed -r \ -e 's/([ \t(])(__user|__force|__iomem)[ \t]/\1/g' \ -e 's/__attribute_const__([ \t]|$)/\1/g' \ - -e 's@^#include @@' \ + -e 's@^#include @@' \ -e 's/(^|[^a-zA-Z0-9])__packed([^a-zA-Z0-9_]|$)/\1__attribute__((packed))\2/g' \ -e 's/(^|[ \t(])(inline|asm|volatile)([ \t(]|$)/\1__\2__\3/g' \ -e 's@#(ifndef|define|endif[ \t]*/[*])[ \t]*_UAPI@#\1 @' \ From patchwork Thu Oct 12 14:26:16 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 115634 Delivered-To: patch@linaro.org Received: by 10.140.22.163 with SMTP id 32csp2003417qgn; Thu, 12 Oct 2017 07:26:20 -0700 (PDT) X-Google-Smtp-Source: AOwi7QC9EHdrgoEqCCSMY8cBA5cYn22DBKvB5M1EcQ8+QQSevMqV4bvon2C7NH/UtO9XHfBnE+dr X-Received: by 10.84.224.195 with SMTP id k3mr370905pln.403.1507818380345; Thu, 12 Oct 2017 07:26:20 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1507818380; cv=none; d=google.com; s=arc-20160816; b=dU7i6p5aSOXZFK8fr+sdTu3/Obo5o/WtYT4QMeg5WZylpYuR3xU21Ow+IGZ/POj+ze 3BKJU2Zw0Edcb/7pbVxjsUoa3AqE63OsLFCvJDRh0qQ1Sbd+b0KDAmHJwqs1+a8lIBKL Je3x/wZSEJRgwYJjylE8FnrsTGfKUCo4uoyMX7g5rIHDgWwwKfl8pQ0ataw2fqiQ9v9D p+pQADqDYMnoHFNCBwnij+CVoMBzL85m4vSC2InTbKCNeZ4+k8/Ljosq63X3jdDbbrao 7NUI8q3Bj25Fazrfm5hdoimsD+AwC2FGSwYCkACEdrbK2VGA7sOIdq9hCv7OIasBC6Lb r7TQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :arc-authentication-results; bh=6Cs7SdprzdFwao+DS6rt2zMzJZbQeblhc313Xa6mbZ4=; b=dsSN9lmLPqj2LQ1+yz1tXBTbGuuRRYK7rMEIQqFQQvPVMyqMCumRAlijGTbP3yXazM zvSeml0WlXLl3dvKJ70pVvTkjAL18ZT7lSJyTq1O4fmz6XUITdL0chO+eSAuLEK163+8 HYfET8/Ltr4dLTJylp+1HFzzoHwawYVqB4ZkqsK1Q3HO+ytOPemH3hzmRQUnQLliMx3x qICwJCGOgeeSanGvLBme5HqSn7tMD7Et8MZJh6LSI+FwL/GmpcpUNSmuB0i4yU4dx4Dc VuY+SXD1KJKO9ndm7afUNJsLutzYS1rE5hyb79hX9heOC1Vx5r+oX5SWofX5rcaZh33S TSlw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id o129si12483338pfo.203.2017.10.12.07.26.20; Thu, 12 Oct 2017 07:26:20 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752494AbdJLO0S (ORCPT + 27 others); Thu, 12 Oct 2017 10:26:18 -0400 Received: from foss.arm.com ([217.140.101.70]:47910 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752221AbdJLO0P (ORCPT ); Thu, 12 Oct 2017 10:26:15 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1ECED1610; Thu, 12 Oct 2017 07:26:15 -0700 (PDT) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id C14563F5B3; Thu, 12 Oct 2017 07:26:14 -0700 (PDT) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id 75E751AE2DDA; Thu, 12 Oct 2017 15:26:18 +0100 (BST) From: Will Deacon To: paulmck@linux.vnet.ibm.com Cc: linux-kernel@vger.kernel.org, mcree@orcon.net.nz, peterz@infradead.org, rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, linux-alpha@vger.kernel.org, Will Deacon Subject: [PATCH 2/3] locking/barriers: Kill lockless_dereference Date: Thu, 12 Oct 2017 15:26:16 +0100 Message-Id: <1507818377-7546-3-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1507818377-7546-1-git-send-email-will.deacon@arm.com> References: <1507818377-7546-1-git-send-email-will.deacon@arm.com> MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org lockless_dereference is a nice idea, but its gained little traction in kernel code since it's introduction three years ago. This is partly because it's a pain to type, but also because using READ_ONCE instead will work correctly on all architectures apart from Alpha, which is a fully supported but somewhat niche architecture these days. This patch moves smp_read_barrier_depends() (a NOP on all architectures other than Alpha) from lockless_dereference into READ_ONCE, converts the few actual users over to READ_ONCE and then finally removes lockless_dereference altogether. Signed-off-by: Will Deacon --- Documentation/memory-barriers.txt | 12 ------------ .../translations/ko_KR/memory-barriers.txt | 12 ------------ arch/x86/events/core.c | 2 +- arch/x86/include/asm/mmu_context.h | 4 ++-- arch/x86/kernel/ldt.c | 2 +- drivers/md/dm-mpath.c | 20 ++++++++++---------- fs/dcache.c | 4 ++-- fs/overlayfs/ovl_entry.h | 2 +- fs/overlayfs/readdir.c | 2 +- include/linux/compiler.h | 21 +-------------------- include/linux/rculist.h | 4 ++-- include/linux/rcupdate.h | 4 ++-- kernel/events/core.c | 4 ++-- kernel/seccomp.c | 2 +- kernel/task_work.c | 2 +- mm/slab.h | 2 +- 16 files changed, 28 insertions(+), 71 deletions(-) -- 2.1.4 Reviewed-by: Paul E. McKenney diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index b759a60624fd..470a682f3fa4 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -1886,18 +1886,6 @@ There are some more advanced barrier functions: See Documentation/atomic_{t,bitops}.txt for more information. - (*) lockless_dereference(); - - This can be thought of as a pointer-fetch wrapper around the - smp_read_barrier_depends() data-dependency barrier. - - This is also similar to rcu_dereference(), but in cases where - object lifetime is handled by some mechanism other than RCU, for - example, when the objects removed only when the system goes down. - In addition, lockless_dereference() is used in some data structures - that can be used both with and without RCU. - - (*) dma_wmb(); (*) dma_rmb(); diff --git a/Documentation/translations/ko_KR/memory-barriers.txt b/Documentation/translations/ko_KR/memory-barriers.txt index a7a813258013..ec3b46e27b7a 100644 --- a/Documentation/translations/ko_KR/memory-barriers.txt +++ b/Documentation/translations/ko_KR/memory-barriers.txt @@ -1858,18 +1858,6 @@ Mandatory 배리어들은 SMP 시스템에서도 UP 시스템에서도 SMP 효 참고하세요. - (*) lockless_dereference(); - - 이 함수는 smp_read_barrier_depends() 데이터 의존성 배리어를 사용하는 - 포인터 읽어오기 래퍼(wrapper) 함수로 생각될 수 있습니다. - - 객체의 라이프타임이 RCU 외의 메커니즘으로 관리된다는 점을 제외하면 - rcu_dereference() 와도 유사한데, 예를 들면 객체가 시스템이 꺼질 때에만 - 제거되는 경우 등입니다. 또한, lockless_dereference() 은 RCU 와 함께 - 사용될수도, RCU 없이 사용될 수도 있는 일부 데이터 구조에 사용되고 - 있습니다. - - (*) dma_wmb(); (*) dma_rmb(); diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 80534d3c2480..589af1eec7c1 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2371,7 +2371,7 @@ static unsigned long get_segment_base(unsigned int segment) struct ldt_struct *ldt; /* IRQs are off, so this synchronizes with smp_store_release */ - ldt = lockless_dereference(current->active_mm->context.ldt); + ldt = READ_ONCE(current->active_mm->context.ldt); if (!ldt || idx >= ldt->nr_entries) return 0; diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index c120b5db178a..9037a4e546e8 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -72,8 +72,8 @@ static inline void load_mm_ldt(struct mm_struct *mm) #ifdef CONFIG_MODIFY_LDT_SYSCALL struct ldt_struct *ldt; - /* lockless_dereference synchronizes with smp_store_release */ - ldt = lockless_dereference(mm->context.ldt); + /* READ_ONCE synchronizes with smp_store_release */ + ldt = READ_ONCE(mm->context.ldt); /* * Any change to mm->context.ldt is followed by an IPI to all diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c index f0e64db18ac8..0a21390642c4 100644 --- a/arch/x86/kernel/ldt.c +++ b/arch/x86/kernel/ldt.c @@ -101,7 +101,7 @@ static void finalize_ldt_struct(struct ldt_struct *ldt) static void install_ldt(struct mm_struct *current_mm, struct ldt_struct *ldt) { - /* Synchronizes with lockless_dereference in load_mm_ldt. */ + /* Synchronizes with READ_ONCE in load_mm_ldt. */ smp_store_release(¤t_mm->context.ldt, ldt); /* Activate the LDT for all CPUs using current_mm. */ diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index 11f273d2f018..3f88c9d32f7e 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -366,7 +366,7 @@ static struct pgpath *choose_path_in_pg(struct multipath *m, pgpath = path_to_pgpath(path); - if (unlikely(lockless_dereference(m->current_pg) != pg)) { + if (unlikely(READ_ONCE(m->current_pg) != pg)) { /* Only update current_pgpath if pg changed */ spin_lock_irqsave(&m->lock, flags); m->current_pgpath = pgpath; @@ -390,7 +390,7 @@ static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes) } /* Were we instructed to switch PG? */ - if (lockless_dereference(m->next_pg)) { + if (READ_ONCE(m->next_pg)) { spin_lock_irqsave(&m->lock, flags); pg = m->next_pg; if (!pg) { @@ -406,7 +406,7 @@ static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes) /* Don't change PG until it has no remaining paths */ check_current_pg: - pg = lockless_dereference(m->current_pg); + pg = READ_ONCE(m->current_pg); if (pg) { pgpath = choose_path_in_pg(m, pg, nr_bytes); if (!IS_ERR_OR_NULL(pgpath)) @@ -473,7 +473,7 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq, struct request *clone; /* Do we need to select a new pgpath? */ - pgpath = lockless_dereference(m->current_pgpath); + pgpath = READ_ONCE(m->current_pgpath); if (!pgpath || !test_bit(MPATHF_QUEUE_IO, &m->flags)) pgpath = choose_pgpath(m, nr_bytes); @@ -535,7 +535,7 @@ static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_m bool queue_io; /* Do we need to select a new pgpath? */ - pgpath = lockless_dereference(m->current_pgpath); + pgpath = READ_ONCE(m->current_pgpath); queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags); if (!pgpath || !queue_io) pgpath = choose_pgpath(m, nr_bytes); @@ -1804,7 +1804,7 @@ static int multipath_prepare_ioctl(struct dm_target *ti, struct pgpath *current_pgpath; int r; - current_pgpath = lockless_dereference(m->current_pgpath); + current_pgpath = READ_ONCE(m->current_pgpath); if (!current_pgpath) current_pgpath = choose_pgpath(m, 0); @@ -1826,7 +1826,7 @@ static int multipath_prepare_ioctl(struct dm_target *ti, } if (r == -ENOTCONN) { - if (!lockless_dereference(m->current_pg)) { + if (!READ_ONCE(m->current_pg)) { /* Path status changed, redo selection */ (void) choose_pgpath(m, 0); } @@ -1895,9 +1895,9 @@ static int multipath_busy(struct dm_target *ti) return (m->queue_mode != DM_TYPE_MQ_REQUEST_BASED); /* Guess which priority_group will be used at next mapping time */ - pg = lockless_dereference(m->current_pg); - next_pg = lockless_dereference(m->next_pg); - if (unlikely(!lockless_dereference(m->current_pgpath) && next_pg)) + pg = READ_ONCE(m->current_pg); + next_pg = READ_ONCE(m->next_pg); + if (unlikely(!READ_ONCE(m->current_pgpath) && next_pg)) pg = next_pg; if (!pg) { diff --git a/fs/dcache.c b/fs/dcache.c index f90141387f01..34c852af215c 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -231,7 +231,7 @@ static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *c { /* * Be careful about RCU walk racing with rename: - * use 'lockless_dereference' to fetch the name pointer. + * use 'READ_ONCE' to fetch the name pointer. * * NOTE! Even if a rename will mean that the length * was not loaded atomically, we don't care. The @@ -245,7 +245,7 @@ static inline int dentry_cmp(const struct dentry *dentry, const unsigned char *c * early because the data cannot match (there can * be no NUL in the ct/tcount data) */ - const unsigned char *cs = lockless_dereference(dentry->d_name.name); + const unsigned char *cs = READ_ONCE(dentry->d_name.name); return dentry_string_cmp(cs, ct, tcount); } diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index 25d9b5adcd42..36b49bd09264 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -77,5 +77,5 @@ static inline struct ovl_inode *OVL_I(struct inode *inode) static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi) { - return lockless_dereference(oi->__upperdentry); + return READ_ONCE(oi->__upperdentry); } diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index 0f85ee9c3268..c67a7703296b 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -754,7 +754,7 @@ static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end, if (!od->is_upper && OVL_TYPE_UPPER(ovl_path_type(dentry))) { struct inode *inode = file_inode(file); - realfile = lockless_dereference(od->upperfile); + realfile = READ_ONCE(od->upperfile); if (!realfile) { struct path upperpath; diff --git a/include/linux/compiler.h b/include/linux/compiler.h index c714239f453f..4517662f128c 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -242,6 +242,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s __read_once_size(&(x), __u.__c, sizeof(x)); \ else \ __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ + smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ __u.__val; \ }) #define READ_ONCE(x) __READ_ONCE(x, 1) @@ -345,24 +346,4 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s (volatile typeof(x) *)&(x); }) #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x)) -/** - * lockless_dereference() - safely load a pointer for later dereference - * @p: The pointer to load - * - * Similar to rcu_dereference(), but for situations where the pointed-to - * object's lifetime is managed by something other than RCU. That - * "something other" might be reference counting or simple immortality. - * - * The seemingly unused variable ___typecheck_p validates that @p is - * indeed a pointer type by using a pointer to typeof(*p) as the type. - * Taking a pointer to typeof(*p) again is needed in case p is void *. - */ -#define lockless_dereference(p) \ -({ \ - typeof(p) _________p1 = READ_ONCE(p); \ - typeof(*(p)) *___typecheck_p __maybe_unused; \ - smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ - (_________p1); \ -}) - #endif /* __LINUX_COMPILER_H */ diff --git a/include/linux/rculist.h b/include/linux/rculist.h index b1fd8bf85fdc..3a2bb7d8ed4d 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -274,7 +274,7 @@ static inline void list_splice_tail_init_rcu(struct list_head *list, * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). */ #define list_entry_rcu(ptr, type, member) \ - container_of(lockless_dereference(ptr), type, member) + container_of(READ_ONCE(ptr), type, member) /** * Where are list_empty_rcu() and list_first_entry_rcu()? @@ -367,7 +367,7 @@ static inline void list_splice_tail_init_rcu(struct list_head *list, * example is when items are added to the list, but never deleted. */ #define list_entry_lockless(ptr, type, member) \ - container_of((typeof(ptr))lockless_dereference(ptr), type, member) + container_of((typeof(ptr))READ_ONCE(ptr), type, member) /** * list_for_each_entry_lockless - iterate over rcu list of given type diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index de50d8a4cf41..380a3aeb09d7 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -346,7 +346,7 @@ static inline void rcu_preempt_sleep_check(void) { } #define __rcu_dereference_check(p, c, space) \ ({ \ /* Dependency order vs. p above. */ \ - typeof(*p) *________p1 = (typeof(*p) *__force)lockless_dereference(p); \ + typeof(*p) *________p1 = (typeof(*p) *__force)READ_ONCE(p); \ RCU_LOCKDEP_WARN(!(c), "suspicious rcu_dereference_check() usage"); \ rcu_dereference_sparse(p, space); \ ((typeof(*p) __force __kernel *)(________p1)); \ @@ -360,7 +360,7 @@ static inline void rcu_preempt_sleep_check(void) { } #define rcu_dereference_raw(p) \ ({ \ /* Dependency order vs. p above. */ \ - typeof(p) ________p1 = lockless_dereference(p); \ + typeof(p) ________p1 = READ_ONCE(p); \ ((typeof(*p) __force __kernel *)(________p1)); \ }) diff --git a/kernel/events/core.c b/kernel/events/core.c index 6bc21e202ae4..417812ce0099 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4231,7 +4231,7 @@ static void perf_remove_from_owner(struct perf_event *event) * indeed free this event, otherwise we need to serialize on * owner->perf_event_mutex. */ - owner = lockless_dereference(event->owner); + owner = READ_ONCE(event->owner); if (owner) { /* * Since delayed_put_task_struct() also drops the last @@ -4328,7 +4328,7 @@ int perf_event_release_kernel(struct perf_event *event) * Cannot change, child events are not migrated, see the * comment with perf_event_ctx_lock_nested(). */ - ctx = lockless_dereference(child->ctx); + ctx = READ_ONCE(child->ctx); /* * Since child_mutex nests inside ctx::mutex, we must jump * through hoops. We start by grabbing a reference on the ctx. diff --git a/kernel/seccomp.c b/kernel/seccomp.c index bb3a38005b9c..1daa8b61a268 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -189,7 +189,7 @@ static u32 seccomp_run_filters(const struct seccomp_data *sd, u32 ret = SECCOMP_RET_ALLOW; /* Make sure cross-thread synced filter points somewhere sane. */ struct seccomp_filter *f = - lockless_dereference(current->seccomp.filter); + READ_ONCE(current->seccomp.filter); /* Ensure unexpected behavior doesn't result in failing open. */ if (unlikely(WARN_ON(f == NULL))) diff --git a/kernel/task_work.c b/kernel/task_work.c index 836a72a66fba..9a9f262fc53d 100644 --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -67,7 +67,7 @@ task_work_cancel(struct task_struct *task, task_work_func_t func) * we raced with task_work_run(), *pprev == NULL/exited. */ raw_spin_lock_irqsave(&task->pi_lock, flags); - while ((work = lockless_dereference(*pprev))) { + while ((work = READ_ONCE(*pprev))) { if (work->func != func) pprev = &work->next; else if (cmpxchg(pprev, work, work->next) == work) diff --git a/mm/slab.h b/mm/slab.h index 073362816acc..8894f811a89d 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -258,7 +258,7 @@ cache_from_memcg_idx(struct kmem_cache *s, int idx) * memcg_caches issues a write barrier to match this (see * memcg_create_kmem_cache()). */ - cachep = lockless_dereference(arr->entries[idx]); + cachep = READ_ONCE(arr->entries[idx]); rcu_read_unlock(); return cachep; From patchwork Thu Oct 12 14:26:17 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 115635 Delivered-To: patch@linaro.org Received: by 10.140.22.163 with SMTP id 32csp2003450qgn; Thu, 12 Oct 2017 07:26:22 -0700 (PDT) X-Google-Smtp-Source: AOwi7QAAw5/KHpHHHDVlRnJxVdnjyUIrFtFqtiZDBCqoCVE2DNS8ShMUUzWpm6oZ/vbXF2HAQgds X-Received: by 10.99.101.68 with SMTP id z65mr379562pgb.205.1507818381920; Thu, 12 Oct 2017 07:26:21 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1507818381; cv=none; d=google.com; s=arc-20160816; b=miUQR+I14mBKnQVBbav3cNOLdNmuEJUoADHKgv3VbRjByVEfULvumYB83mfWSKRMN3 iyEpI6oZJPi/8NTBmSwuGen5LcDUTY+zeipO7+ewQ9cfZ1D/HM4yd04xYo/6rDzpeN87 buwH0n5jw+oTBJNYQcUx87raHbEGtlOP1qmGDRm8Y1hJtKEREGFqqvQX1FuQngE+Kke9 AMGpDSEG3Q/wUqTGNrSvZrlJJ7rtT0XBOYF4CnSNoS447J7djpNPrX3Qhg6BFyyM93Bs RkUdOgE0A8lDpr/bjDR66DFHwVk0R/guXyil/CbYQu75HD64Ok73KQ2rSpwofiuE5G4T Chzg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=H5PTFV7hS/TDgppTTAVjTRAHxSxpVJ6UtxANFounLgA=; b=Q1TUQhxSTfadbZNeVabBbBdVtX7EISHA/tMqHaxDx1GlhhplL1K+2tEuBN+YkDIRcr TeiebEnWLmG8MYezwbGqxnARo9R2khmfAFRkflBboUsHBiWjeYxB5mlynFBnQpTkzx/f wuq4WPwlQugMvtVd8aiZ2nqHpWBJBoUYIM4n22RwQaZ2zJHcfyi5keAFH+J1nSmU8qoZ WIFutsVhXH/K6E8c8yeEv2LdIuHXICiDNzAqOHr8kSm/InTva1yT6fFftCXo7NKAJE9s QmY6224FLXbkRyXmRGiH9cB/gSzIAMp/N8pSYQcul6w0b0dKj2Lf0X7PvmWCKpiUIORV s7BA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id o129si12483338pfo.203.2017.10.12.07.26.21; Thu, 12 Oct 2017 07:26:21 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752628AbdJLO0T (ORCPT + 27 others); Thu, 12 Oct 2017 10:26:19 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:47894 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752213AbdJLO0P (ORCPT ); Thu, 12 Oct 2017 10:26:15 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 12F8415BF; Thu, 12 Oct 2017 07:26:15 -0700 (PDT) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D81533F236; Thu, 12 Oct 2017 07:26:14 -0700 (PDT) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id 8630A1AE2DFF; Thu, 12 Oct 2017 15:26:18 +0100 (BST) From: Will Deacon To: paulmck@linux.vnet.ibm.com Cc: linux-kernel@vger.kernel.org, mcree@orcon.net.nz, peterz@infradead.org, rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, linux-alpha@vger.kernel.org, Will Deacon Subject: [PATCH 3/3] alpha: atomics: Add smp_read_barrier_depends() to release/relaxed atomics Date: Thu, 12 Oct 2017 15:26:17 +0100 Message-Id: <1507818377-7546-4-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1507818377-7546-1-git-send-email-will.deacon@arm.com> References: <1507818377-7546-1-git-send-email-will.deacon@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As part of the fight against smp_read_barrier_depends(), we require dependency ordering to be preserved when a dependency is headed by a load performed using an atomic operation. This patch adds smp_read_barrier_depends() to the _release and _relaxed atomics on alpha, which otherwise lack anything to enforce dependency ordering. Signed-off-by: Will Deacon --- arch/alpha/include/asm/atomic.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) -- 2.1.4 Reviewed-by: Paul E. McKenney diff --git a/arch/alpha/include/asm/atomic.h b/arch/alpha/include/asm/atomic.h index 498933a7df97..16961a3f45ba 100644 --- a/arch/alpha/include/asm/atomic.h +++ b/arch/alpha/include/asm/atomic.h @@ -13,6 +13,15 @@ * than regular operations. */ +/* + * To ensure dependency ordering is preserved for the _relaxed and + * _release atomics, an smp_read_barrier_depends() is unconditionally + * inserted into the _relaxed variants, which are used to build the + * barriered versions. To avoid redundant back-to-back fences, we can + * define the _acquire and _fence versions explicitly. + */ +#define __atomic_op_acquire(op, args...) op##_relaxed(args) +#define __atomic_op_fence __atomic_op_release #define ATOMIC_INIT(i) { (i) } #define ATOMIC64_INIT(i) { (i) } @@ -60,6 +69,7 @@ static inline int atomic_##op##_return_relaxed(int i, atomic_t *v) \ ".previous" \ :"=&r" (temp), "=m" (v->counter), "=&r" (result) \ :"Ir" (i), "m" (v->counter) : "memory"); \ + smp_read_barrier_depends(); \ return result; \ } @@ -77,6 +87,7 @@ static inline int atomic_fetch_##op##_relaxed(int i, atomic_t *v) \ ".previous" \ :"=&r" (temp), "=m" (v->counter), "=&r" (result) \ :"Ir" (i), "m" (v->counter) : "memory"); \ + smp_read_barrier_depends(); \ return result; \ } @@ -111,6 +122,7 @@ static __inline__ long atomic64_##op##_return_relaxed(long i, atomic64_t * v) \ ".previous" \ :"=&r" (temp), "=m" (v->counter), "=&r" (result) \ :"Ir" (i), "m" (v->counter) : "memory"); \ + smp_read_barrier_depends(); \ return result; \ } @@ -128,6 +140,7 @@ static __inline__ long atomic64_fetch_##op##_relaxed(long i, atomic64_t * v) \ ".previous" \ :"=&r" (temp), "=m" (v->counter), "=&r" (result) \ :"Ir" (i), "m" (v->counter) : "memory"); \ + smp_read_barrier_depends(); \ return result; \ }