From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:54138 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753223AbXH1IJz (ORCPT ); Tue, 28 Aug 2007 04:09:55 -0400 From: Nick Piggin Date: Sun, 05 Aug 2007 06:28:29 +1000 Message-Id: <20070804202829.13550.15847.sendpatchset@linux.local0.net> In-Reply-To: <20070804202820.13550.67814.sendpatchset@linux.local0.net> References: <20070804202820.13550.67814.sendpatchset@linux.local0.net> Subject: [patch 1/8] bitops: introduce lock ops Sender: linux-arch-owner@vger.kernel.org To: Andrew Morton Cc: Nick Piggin , Linux Arch List-ID: Introduce test_and_set_bit_lock / clear_bit_unlock bitops with lock semantics. Convert all architectures to use the generic implementation. Signed-off-by: Nick Piggin Acked-By: David Howells --- Documentation/atomic_ops.txt | 14 +++++++++++ Documentation/memory-barriers.txt | 14 ++++++++++- include/asm-alpha/bitops.h | 1 include/asm-arm/bitops.h | 1 include/asm-avr32/bitops.h | 1 include/asm-blackfin/bitops.h | 1 include/asm-cris/bitops.h | 1 include/asm-frv/bitops.h | 1 include/asm-generic/bitops.h | 1 include/asm-generic/bitops/lock.h | 45 ++++++++++++++++++++++++++++++++++++++ include/asm-h8300/bitops.h | 1 include/asm-i386/bitops.h | 1 include/asm-ia64/bitops.h | 2 + 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 | 1 include/asm-powerpc/bitops.h | 1 include/asm-s390/bitops.h | 1 include/asm-sh/bitops.h | 1 include/asm-sh64/bitops.h | 1 include/asm-sparc/bitops.h | 1 include/asm-sparc64/bitops.h | 1 include/asm-v850/bitops.h | 1 include/asm-x86_64/bitops.h | 1 include/asm-xtensa/bitops.h | 1 27 files changed, 96 insertions(+), 2 deletions(-) Index: linux-2.6/include/asm-alpha/bitops.h =================================================================== --- linux-2.6.orig/include/asm-alpha/bitops.h +++ linux-2.6/include/asm-alpha/bitops.h @@ -367,6 +367,7 @@ static inline unsigned int hweight8(unsi #else #include #endif +#include #endif /* __KERNEL__ */ Index: linux-2.6/include/asm-arm/bitops.h =================================================================== --- linux-2.6.orig/include/asm-arm/bitops.h +++ linux-2.6/include/asm-arm/bitops.h @@ -286,6 +286,7 @@ static inline int constant_fls(int x) #include #include +#include /* * Ext2 is defined to use little-endian byte ordering. Index: linux-2.6/include/asm-avr32/bitops.h =================================================================== --- linux-2.6.orig/include/asm-avr32/bitops.h +++ linux-2.6/include/asm-avr32/bitops.h @@ -288,6 +288,7 @@ static inline int ffs(unsigned long word #include #include #include +#include #include #include Index: linux-2.6/include/asm-cris/bitops.h =================================================================== --- linux-2.6.orig/include/asm-cris/bitops.h +++ linux-2.6/include/asm-cris/bitops.h @@ -154,6 +154,7 @@ static inline int test_and_change_bit(in #include #include #include +#include #include Index: linux-2.6/include/asm-frv/bitops.h =================================================================== --- linux-2.6.orig/include/asm-frv/bitops.h +++ linux-2.6/include/asm-frv/bitops.h @@ -302,6 +302,7 @@ int __ilog2_u64(u64 n) #include #include +#include #include Index: linux-2.6/include/asm-generic/bitops.h =================================================================== --- linux-2.6.orig/include/asm-generic/bitops.h +++ linux-2.6/include/asm-generic/bitops.h @@ -22,6 +22,7 @@ #include #include #include +#include #include #include Index: linux-2.6/include/asm-generic/bitops/lock.h =================================================================== --- /dev/null +++ linux-2.6/include/asm-generic/bitops/lock.h @@ -0,0 +1,45 @@ +#ifndef _ASM_GENERIC_BITOPS_LOCK_H_ +#define _ASM_GENERIC_BITOPS_LOCK_H_ + +/** + * test_and_set_bit_lock - Set a bit and return its old value, for lock + * @nr: Bit to set + * @addr: Address to count from + * + * This operation is atomic and provides acquire barrier semantics. + * It can be used to implement bit locks. + */ +#define test_and_set_bit_lock(nr, addr) test_and_set_bit(nr, addr) + +/** + * clear_bit_unlock - Clear a bit in memory, for unlock + * @nr: the bit to set + * @addr: the address to start counting from + * + * This operation is atomic and provides release barrier semantics. + */ +#define clear_bit_unlock(nr, addr) \ +do { \ + smp_mb__before_clear_bit(); \ + clear_bit(nr, addr); \ +} while (0) + +/** + * __clear_bit_unlock - Clear a bit in memory, for unlock + * @nr: the bit to set + * @addr: the address to start counting from + * + * This operation is like clear_bit_unlock, however it is not atomic. + * It does provide release barrier semantics so it can be used to unlock + * a bit lock, however it would only be used if no other CPU can modify + * any bits in the memory until the lock is released (a good example is + * if the bit lock itself protects access to the other bits in the word). + */ +#define __clear_bit_unlock(nr, addr) \ +do { \ + smp_mb(); \ + __clear_bit(nr, addr); \ +} while (0) + +#endif /* _ASM_GENERIC_BITOPS_LOCK_H_ */ + Index: linux-2.6/include/asm-h8300/bitops.h =================================================================== --- linux-2.6.orig/include/asm-h8300/bitops.h +++ linux-2.6/include/asm-h8300/bitops.h @@ -194,6 +194,7 @@ static __inline__ unsigned long __ffs(un #include #include #include +#include #include #include #include Index: linux-2.6/include/asm-i386/bitops.h =================================================================== --- linux-2.6.orig/include/asm-i386/bitops.h +++ linux-2.6/include/asm-i386/bitops.h @@ -402,6 +402,7 @@ static inline int fls(int x) } #include +#include #endif /* __KERNEL__ */ Index: linux-2.6/include/asm-m32r/bitops.h =================================================================== --- linux-2.6.orig/include/asm-m32r/bitops.h +++ linux-2.6/include/asm-m32r/bitops.h @@ -255,6 +255,7 @@ static __inline__ int test_and_change_bi #include #include #include +#include #endif /* __KERNEL__ */ Index: linux-2.6/include/asm-m68k/bitops.h =================================================================== --- linux-2.6.orig/include/asm-m68k/bitops.h +++ linux-2.6/include/asm-m68k/bitops.h @@ -314,6 +314,7 @@ static inline int fls(int x) #include #include #include +#include /* Bitmap functions for the minix filesystem */ Index: linux-2.6/include/asm-m68knommu/bitops.h =================================================================== --- linux-2.6.orig/include/asm-m68knommu/bitops.h +++ linux-2.6/include/asm-m68knommu/bitops.h @@ -160,6 +160,7 @@ static __inline__ int __test_bit(int nr, #include #include +#include static __inline__ int ext2_set_bit(int nr, volatile void * addr) { Index: linux-2.6/include/asm-mips/bitops.h =================================================================== --- linux-2.6.orig/include/asm-mips/bitops.h +++ linux-2.6/include/asm-mips/bitops.h @@ -556,6 +556,7 @@ static inline int ffs(int word) #include #include +#include #include #include #include Index: linux-2.6/include/asm-parisc/bitops.h =================================================================== --- linux-2.6.orig/include/asm-parisc/bitops.h +++ linux-2.6/include/asm-parisc/bitops.h @@ -208,6 +208,7 @@ static __inline__ int fls(int x) #include #include +#include #include #endif /* __KERNEL__ */ Index: linux-2.6/include/asm-s390/bitops.h =================================================================== --- linux-2.6.orig/include/asm-s390/bitops.h +++ linux-2.6/include/asm-s390/bitops.h @@ -746,6 +746,7 @@ static inline int sched_find_first_bit(u #include #include +#include /* * ATTENTION: intel byte ordering convention for ext2 and minix !! Index: linux-2.6/include/asm-sh/bitops.h =================================================================== --- linux-2.6.orig/include/asm-sh/bitops.h +++ linux-2.6/include/asm-sh/bitops.h @@ -137,6 +137,7 @@ static inline unsigned long __ffs(unsign #include #include #include +#include #include #include #include Index: linux-2.6/include/asm-sh64/bitops.h =================================================================== --- linux-2.6.orig/include/asm-sh64/bitops.h +++ linux-2.6/include/asm-sh64/bitops.h @@ -136,6 +136,7 @@ static __inline__ unsigned long ffz(unsi #include #include #include +#include #include #include #include Index: linux-2.6/include/asm-sparc/bitops.h =================================================================== --- linux-2.6.orig/include/asm-sparc/bitops.h +++ linux-2.6/include/asm-sparc/bitops.h @@ -96,6 +96,7 @@ static inline void change_bit(unsigned l #include #include #include +#include #include #include #include Index: linux-2.6/include/asm-sparc64/bitops.h =================================================================== --- linux-2.6.orig/include/asm-sparc64/bitops.h +++ linux-2.6/include/asm-sparc64/bitops.h @@ -81,6 +81,7 @@ static inline unsigned int hweight8(unsi #include #endif +#include #endif /* __KERNEL__ */ #include Index: linux-2.6/include/asm-v850/bitops.h =================================================================== --- linux-2.6.orig/include/asm-v850/bitops.h +++ linux-2.6/include/asm-v850/bitops.h @@ -145,6 +145,7 @@ static inline int __test_bit (int nr, co #include #include #include +#include #include #define ext2_set_bit_atomic(l,n,a) test_and_set_bit(n,a) Index: linux-2.6/include/asm-xtensa/bitops.h =================================================================== --- linux-2.6.orig/include/asm-xtensa/bitops.h +++ linux-2.6/include/asm-xtensa/bitops.h @@ -108,6 +108,7 @@ static inline int fls (unsigned int x) #endif #include +#include #include #include Index: linux-2.6/Documentation/atomic_ops.txt =================================================================== --- linux-2.6.orig/Documentation/atomic_ops.txt +++ linux-2.6/Documentation/atomic_ops.txt @@ -369,6 +369,20 @@ brothers: */ smp_mb__after_clear_bit(); +There are two special bitops with lock barrier semantics (acquire/release, +same as spinlocks). These operate in the same way as their non-_lock/unlock +postfixed variants, except that they are to provide acquire/release semantics, +respectively. This means they can be used for bit_spin_trylock and +bit_spin_unlock type operations without specifying any more barriers. + + int test_and_set_bit_lock(unsigned long nr, unsigned long *addr); + void clear_bit_unlock(unsigned long nr, unsigned long *addr); + void __clear_bit_unlock(unsigned long nr, unsigned long *addr); + +The __clear_bit_unlock version is non-atomic, however it still implements +unlock barrier semantics. This can be useful if the lock itself is protecting +the other bits in the word. + Finally, there are non-atomic versions of the bitmask operations provided. They are used in contexts where some other higher-level SMP locking scheme is being used to protect the bitmask, and thus less Index: linux-2.6/Documentation/memory-barriers.txt =================================================================== --- linux-2.6.orig/Documentation/memory-barriers.txt +++ linux-2.6/Documentation/memory-barriers.txt @@ -1479,7 +1479,8 @@ kernel. Any atomic operation that modifies some state in memory and returns information about the state (old or new) implies an SMP-conditional general memory barrier -(smp_mb()) on each side of the actual operation. These include: +(smp_mb()) on each side of the actual operation (with the exception of +explicit lock operations, described later). These include: xchg(); cmpxchg(); @@ -1536,10 +1537,19 @@ If they're used for constructing a lock do need memory barriers as a lock primitive generally has to do things in a specific order. - Basically, each usage case has to be carefully considered as to whether memory barriers are needed or not. +The following operations are special locking primitives: + + test_and_set_bit_lock(); + clear_bit_unlock(); + __clear_bit_unlock(); + +These implement LOCK-class and UNLOCK-class operations. These should be used in +preference to other operations when implementing locking primitives, because +their implementations can be optimised on many architectures. + [!] Note that special memory barrier primitives are available for these situations because on some CPUs the atomic instructions used imply full memory barriers, and so barrier instructions are superfluous in conjunction with them, Index: linux-2.6/include/asm-blackfin/bitops.h =================================================================== --- linux-2.6.orig/include/asm-blackfin/bitops.h +++ linux-2.6/include/asm-blackfin/bitops.h @@ -199,6 +199,7 @@ static __inline__ int __test_bit(int nr, #include #include +#include #include #include Index: linux-2.6/include/asm-x86_64/bitops.h =================================================================== --- linux-2.6.orig/include/asm-x86_64/bitops.h +++ linux-2.6/include/asm-x86_64/bitops.h @@ -408,6 +408,7 @@ static __inline__ int fls(int x) #define ARCH_HAS_FAST_MULTIPLIER 1 #include +#include #endif /* __KERNEL__ */ Index: linux-2.6/include/asm-ia64/bitops.h =================================================================== --- linux-2.6.orig/include/asm-ia64/bitops.h +++ linux-2.6/include/asm-ia64/bitops.h @@ -371,6 +371,8 @@ hweight64 (unsigned long x) #define hweight16(x) (unsigned int) hweight64((x) & 0xfffful) #define hweight8(x) (unsigned int) hweight64((x) & 0xfful) +#include + #endif /* __KERNEL__ */ #include Index: linux-2.6/include/asm-powerpc/bitops.h =================================================================== --- linux-2.6.orig/include/asm-powerpc/bitops.h +++ linux-2.6/include/asm-powerpc/bitops.h @@ -266,6 +266,7 @@ static __inline__ int fls(unsigned int x #include #include +#include #define find_first_zero_bit(addr, size) find_next_zero_bit((addr), (size), 0) unsigned long find_next_zero_bit(const unsigned long *addr,