Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1032309AbWLGPcs (ORCPT ); Thu, 7 Dec 2006 10:32:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1032306AbWLGPca (ORCPT ); Thu, 7 Dec 2006 10:32:30 -0500 Received: from mx1.redhat.com ([66.187.233.31]:48227 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1032302AbWLGPcZ (ORCPT ); Thu, 7 Dec 2006 10:32:25 -0500 From: David Howells Subject: [PATCH 2/3] WorkStruct: Add assign_bits() to give an atomic-bitops safe assignment Date: Thu, 07 Dec 2006 15:31:41 +0000 To: torvalds@osdl.org, akpm@osdl.org, davem@davemloft.com, wli@holomorphy.com, matthew@wil.cx Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, dhowells@redhat.com Message-Id: <20061207153141.28408.69303.stgit@warthog.cambridge.redhat.com> In-Reply-To: <20061207153138.28408.94099.stgit@warthog.cambridge.redhat.com> References: <20061207153138.28408.94099.stgit@warthog.cambridge.redhat.com> Content-Type: text/plain; charset=utf-8; format=fixed Content-Transfer-Encoding: 8bit User-Agent: StGIT/0.10 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 14968 Lines: 473 Add assign_bits() to give an atomic-bitops safe assignment on all archs without the need for cmpxchg(). This is needed where archs emulate atomic bitops using spinlocks as there's a gap between reading the counter and updating it that a direct assignment could get lost in. Emulation by simply disabling interrupts on a UP-only arch should be sufficient to permit direct assignment to work, provided NMI doesn't try to do bitops. Signed-Off-By: David Howells --- arch/sparc/lib/bitops.S | 24 +++++++++++++++++++++++ include/asm-alpha/bitops.h | 1 + include/asm-arm/bitops.h | 26 ++++++++++++++++++++++++ include/asm-arm26/bitops.h | 9 ++++++++ include/asm-avr32/bitops.h | 1 + include/asm-cris/bitops.h | 1 + include/asm-frv/bitops.h | 1 + include/asm-generic/bitops/assign-bits.h | 32 ++++++++++++++++++++++++++++++ include/asm-generic/bitops/atomic.h | 21 ++++++++++++++++++++ include/asm-h8300/bitops.h | 1 + include/asm-i386/bitops.h | 1 + include/asm-ia64/bitops.h | 1 + include/asm-m32r/bitops.h | 1 + include/asm-m68k/bitops.h | 1 + include/asm-m68knommu/bitops.h | 1 + include/asm-mips/bitops.h | 1 + include/asm-parisc/bitops.h | 9 ++++++++ include/asm-powerpc/bitops.h | 1 + include/asm-s390/bitops.h | 2 ++ include/asm-sh/bitops.h | 1 + include/asm-sh64/bitops.h | 1 + include/asm-sparc/bitops.h | 21 ++++++++++++++++++++ include/asm-sparc64/bitops.h | 1 + include/asm-v850/bitops.h | 1 + include/asm-x86_64/bitops.h | 1 + 25 files changed, 161 insertions(+), 0 deletions(-) diff --git a/arch/sparc/lib/bitops.S b/arch/sparc/lib/bitops.S index cb7fb66..d6b9491 100644 --- a/arch/sparc/lib/bitops.S +++ b/arch/sparc/lib/bitops.S @@ -105,5 +105,29 @@ #endif jmpl %o7, %g0 mov %g4, %o7 + /* And then just replace all the bits with those from %g2. */ + .globl ___assign_bits +___assign_bits: + rd %psr, %g3 + nop; nop; nop + or %g3, PSR_PIL, %g5 + wr %g5, 0x0, %psr + nop; nop; nop +#ifdef CONFIG_SMP + set bitops_spinlock, %g5 +2: ldstub [%g5], %g7 ! Spin on the byte lock for SMP. + orcc %g7, 0x0, %g0 ! Did we get it? + bne 2b ! Nope... + st %g2, [%g1] + set bitops_spinlock, %g5 + stb %g0, [%g5] +#else + st %g2, [%g1] +#endif + wr %g3, 0x0, %psr + nop; nop; nop + jmpl %o7, %g0 + mov %g4, %o7 + .globl __bitops_end __bitops_end: diff --git a/include/asm-alpha/bitops.h b/include/asm-alpha/bitops.h index 4b6ef7f..1263b26 100644 --- a/include/asm-alpha/bitops.h +++ b/include/asm-alpha/bitops.h @@ -2,6 +2,7 @@ #ifndef _ALPHA_BITOPS_H #define _ALPHA_BITOPS_H #include +#include /* * Copyright 1994, Linus Torvalds. diff --git a/include/asm-arm/bitops.h b/include/asm-arm/bitops.h index b41831b..5932134 100644 --- a/include/asm-arm/bitops.h +++ b/include/asm-arm/bitops.h @@ -117,6 +117,32 @@ ____atomic_test_and_change_bit(unsigned return res & mask; } +#if __LINUX_ARM_ARCH__ >= 6 && defined(CONFIG_CPU_32v6K) +static inline void assign_bits(unsigned long v, unsigned long *addr) +{ + unsigned long tmp; + + __asm__ __volatile__("@ atomic_set\n" +"1: ldrex %0, [%1]\n" +" strex %0, %2, [%1]\n" +" teq %0, #0\n" +" bne 1b" + : "=&r" (tmp) + : "r" (addr), "r" (v) + : "cc"); +} + +#else +static inline void assign_bits(unsigned long v, unsigned long *addr) +{ + unsigned long flags; + + raw_local_irq_save(flags); + *addr = v; + raw_local_irq_restore(flags); +} +#endif + #include /* diff --git a/include/asm-arm26/bitops.h b/include/asm-arm26/bitops.h index 19a6957..9b489c0 100644 --- a/include/asm-arm26/bitops.h +++ b/include/asm-arm26/bitops.h @@ -117,6 +117,15 @@ ____atomic_test_and_change_bit(unsigned return res & mask; } +static inline void assign_bits(unsigned long v, unsigned long *addr) +{ + unsigned long flags; + + local_irq_save(flags); + *addr = v; + local_irq_restore(flags); +} + #include /* diff --git a/include/asm-avr32/bitops.h b/include/asm-avr32/bitops.h index 5299f8c..11d8fb0 100644 --- a/include/asm-avr32/bitops.h +++ b/include/asm-avr32/bitops.h @@ -230,6 +230,7 @@ static inline int test_and_change_bit(in return (old & mask) != 0; } +#include #include /* Find First bit Set */ diff --git a/include/asm-cris/bitops.h b/include/asm-cris/bitops.h index a569065..8ea3dc9 100644 --- a/include/asm-cris/bitops.h +++ b/include/asm-cris/bitops.h @@ -141,6 +141,7 @@ static inline int test_and_change_bit(in return retval; } +#include #include /* diff --git a/include/asm-frv/bitops.h b/include/asm-frv/bitops.h index 1f70d47..3af3a03 100644 --- a/include/asm-frv/bitops.h +++ b/include/asm-frv/bitops.h @@ -157,6 +157,7 @@ (__builtin_constant_p(nr) ? \ __constant_test_bit((nr),(addr)) : \ __test_bit((nr),(addr))) +#include #include /** diff --git a/include/asm-generic/bitops/assign-bits.h b/include/asm-generic/bitops/assign-bits.h new file mode 100644 index 0000000..db6d5b2 --- /dev/null +++ b/include/asm-generic/bitops/assign-bits.h @@ -0,0 +1,32 @@ +/* Safely assign a value to a word modified by atomic bitops + * + * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#ifndef _ASM_GENERIC_BITOPS_ASSIGN_BITS_H +#define _ASM_GENERIC_BITOPS_ASSIGN_BITS_H + +/** + * assign_bits - Safely assign to a word containing atomically modified bits + * @v: Value to assign to the word + * @addr: The word to modify + * + * Safely assign a value to a word that contains bits that are atomically + * modified by such as clear_bit() or test_and_set_bit(). + * + * On some arches direct assignment isn't safe because the bitops have to be + * implemented using spinlocks to gain atomicity - which means they're only + * safe with respect to related operations. + */ +static inline void assign_bits(unsigned long v, unsigned long *addr) +{ + *addr = v; +} + +#endif /* _ASM_GENERIC_BITOPS_ASSIGN_BITS_H */ diff --git a/include/asm-generic/bitops/atomic.h b/include/asm-generic/bitops/atomic.h index 7833931..32d2ca7 100644 --- a/include/asm-generic/bitops/atomic.h +++ b/include/asm-generic/bitops/atomic.h @@ -188,4 +188,25 @@ static inline int test_and_change_bit(in return (old & mask) != 0; } +/** + * assign_bits - Safely assign to a word containing atomically modified bits + * @v: Value to assign to the word + * @addr: The word to modify + * + * Safely assign a value to a word that contains bits that are atomically + * modified by such as clear_bit() or test_and_set_bit(). + * + * Direct assignment isn't safe if bitops are implemented using spinlocks to + * gain atomicity - which means they're only safe with respect to related + * operations. + */ +static inline void assign_bits(unsigned long v, volatile unsigned long *addr) +{ + unsigned long flags; + + _atomic_spin_lock_irqsave(addr, flags); + *addr = v; + _atomic_spin_unlock_irqrestore(addr, flags); +} + #endif /* _ASM_GENERIC_BITOPS_ATOMIC_H */ diff --git a/include/asm-h8300/bitops.h b/include/asm-h8300/bitops.h index d76299c..d5dea31 100644 --- a/include/asm-h8300/bitops.h +++ b/include/asm-h8300/bitops.h @@ -175,6 +175,7 @@ #undef H8300_GEN_TEST_BITOP_CONST #undef H8300_GEN_TEST_BITOP_CONST_INT #undef H8300_GEN_TEST_BITOP +#include #include static __inline__ unsigned long __ffs(unsigned long word) diff --git a/include/asm-i386/bitops.h b/include/asm-i386/bitops.h index 1c780fa..51ea0bb 100644 --- a/include/asm-i386/bitops.h +++ b/include/asm-i386/bitops.h @@ -7,6 +7,7 @@ #define _I386_BITOPS_H #include #include +#include /* * These have to be done with inline assembly: that way the bit-setting diff --git a/include/asm-ia64/bitops.h b/include/asm-ia64/bitops.h index 6cc517e..452e565 100644 --- a/include/asm-ia64/bitops.h +++ b/include/asm-ia64/bitops.h @@ -12,6 +12,7 @@ #define _ASM_IA64_BITOPS_H #include #include #include +#include /** * set_bit - Atomically set a bit in memory diff --git a/include/asm-m32r/bitops.h b/include/asm-m32r/bitops.h index 66ab672..bb67351 100644 --- a/include/asm-m32r/bitops.h +++ b/include/asm-m32r/bitops.h @@ -243,6 +243,7 @@ static __inline__ int test_and_change_bi return (oldbit != 0); } +#include #include #include #include diff --git a/include/asm-m68k/bitops.h b/include/asm-m68k/bitops.h index 1a61fdb..8a302ce 100644 --- a/include/asm-m68k/bitops.h +++ b/include/asm-m68k/bitops.h @@ -9,6 +9,7 @@ #define _M68K_BITOPS_H */ #include +#include /* * Require 68020 or better. diff --git a/include/asm-m68knommu/bitops.h b/include/asm-m68knommu/bitops.h index d7fa7d9..75792ba 100644 --- a/include/asm-m68knommu/bitops.h +++ b/include/asm-m68knommu/bitops.h @@ -15,6 +15,7 @@ #include #include #include #include +#include static __inline__ void set_bit(int nr, volatile unsigned long * addr) { diff --git a/include/asm-mips/bitops.h b/include/asm-mips/bitops.h index 06445de..cd18bf9 100644 --- a/include/asm-mips/bitops.h +++ b/include/asm-mips/bitops.h @@ -382,6 +382,7 @@ static inline int test_and_change_bit(un smp_mb(); } +#include #include /* diff --git a/include/asm-parisc/bitops.h b/include/asm-parisc/bitops.h index 9005619..416bd99 100644 --- a/include/asm-parisc/bitops.h +++ b/include/asm-parisc/bitops.h @@ -102,6 +102,15 @@ static __inline__ int test_and_change_bi return (oldbit & mask) ? 1 : 0; } +static inline void assign_bits(unsigned long v, volatile unsigned long *addr) +{ + unsigned long flags; + + _atomic_spin_lock_irqsave(addr, flags); + *addr = v; + _atomic_spin_unlock_irqrestore(addr, flags); +} + #include #ifdef __KERNEL__ diff --git a/include/asm-powerpc/bitops.h b/include/asm-powerpc/bitops.h index c341063..04fe968 100644 --- a/include/asm-powerpc/bitops.h +++ b/include/asm-powerpc/bitops.h @@ -184,6 +184,7 @@ static __inline__ void set_bits(unsigned : "cc"); } +#include #include /* diff --git a/include/asm-s390/bitops.h b/include/asm-s390/bitops.h index f79c9b7..653b965 100644 --- a/include/asm-s390/bitops.h +++ b/include/asm-s390/bitops.h @@ -409,6 +409,8 @@ #define test_and_clear_bit test_and_cle #define test_and_change_bit test_and_change_bit_simple #endif +#include + /* * This routine doesn't need to be atomic. diff --git a/include/asm-sh/bitops.h b/include/asm-sh/bitops.h index 1c16792..342d05a 100644 --- a/include/asm-sh/bitops.h +++ b/include/asm-sh/bitops.h @@ -98,6 +98,7 @@ static inline int test_and_change_bit(in return retval; } +#include #include static inline unsigned long ffz(unsigned long word) diff --git a/include/asm-sh64/bitops.h b/include/asm-sh64/bitops.h index f3bdcdb..b299e6c 100644 --- a/include/asm-sh64/bitops.h +++ b/include/asm-sh64/bitops.h @@ -109,6 +109,7 @@ static __inline__ int test_and_change_bi return retval; } +#include #include static __inline__ unsigned long ffz(unsigned long word) diff --git a/include/asm-sparc/bitops.h b/include/asm-sparc/bitops.h index 04aa331..fa729e4 100644 --- a/include/asm-sparc/bitops.h +++ b/include/asm-sparc/bitops.h @@ -152,6 +152,27 @@ static inline void change_bit(unsigned l : "memory", "cc"); } +static inline void assign_bits(unsigned long v, volatile unsigned long *addr) +{ + register unsigned long value asm("g2"); + register unsigned long *ADDR asm("g1"); + register int tmp1 asm("g3"); + register int tmp2 asm("g4"); + register int tmp3 asm("g5"); + register int tmp4 asm("g7"); + + ADDR = (unsigned long *) addr; + value = v; + + __asm__ __volatile__( + "mov %%o7, %%g4\n\t" + "call ___assign_bits\n\t" + " add %%o7, 8, %%o7\n" + : "=&r" (value), "=r" (tmp1), "=r" (tmp2), "=r" (tmp3), "=r" (tmp4) + : "0" (value), "r" (ADDR) + : "memory", "cc"); +} + #include #define smp_mb__before_clear_bit() do { } while(0) diff --git a/include/asm-sparc64/bitops.h b/include/asm-sparc64/bitops.h index 3d5e1af..a8f7ef1 100644 --- a/include/asm-sparc64/bitops.h +++ b/include/asm-sparc64/bitops.h @@ -17,6 +17,7 @@ extern void set_bit(unsigned long nr, vo extern void clear_bit(unsigned long nr, volatile unsigned long *addr); extern void change_bit(unsigned long nr, volatile unsigned long *addr); +#include #include #ifdef CONFIG_SMP diff --git a/include/asm-v850/bitops.h b/include/asm-v850/bitops.h index 1fa99ba..3bd8fbb 100644 --- a/include/asm-v850/bitops.h +++ b/include/asm-v850/bitops.h @@ -22,6 +22,7 @@ #include /* interrupt en #ifdef __KERNEL__ #include +#include /* * The __ functions are not atomic diff --git a/include/asm-x86_64/bitops.h b/include/asm-x86_64/bitops.h index 5b535ea..3eaa848 100644 --- a/include/asm-x86_64/bitops.h +++ b/include/asm-x86_64/bitops.h @@ -6,6 +6,7 @@ #define _X86_64_BITOPS_H */ #include +#include #define ADDR (*(volatile long *) addr) - 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/