From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Tue, 14 Feb 2006 04:58:45 +0000 (GMT) Received: from ns.miraclelinux.com ([219.118.163.66]:36046 "EHLO mail01.miraclelinux.com") by ftp.linux-mips.org with ESMTP id S8133381AbWBNE6b (ORCPT ); Tue, 14 Feb 2006 04:58:31 +0000 Received: from mail01 (localhost.localdomain [127.0.0.1]) by mail01.miraclelinux.com (Postfix) with ESMTP id 76BF331C329; Tue, 14 Feb 2006 14:04:45 +0900 (JST) Received: from localhost.localdomain (sshgate.miraclelinux.com []) by mail01.miraclelinux.com ([10.1.0.10]); Tue, 14 Feb 2006 05:04:45 +0000 Received: by localhost.localdomain (Postfix, from userid 1000) id 36BC4420236; Tue, 14 Feb 2006 14:04:43 +0900 (JST) Message-Id: <20060214050443.068971000@localhost.localdomain> References: <20060214050351.252615000@localhost.localdomain> Date: Tue, 14 Feb 2006 14:03:58 +0900 From: Akinobu Mita To: linux-kernel@vger.kernel.org Cc: akpm@osdl.org, Russell King , Ian Molton , dev-etrax@axis.com, Hirokazu Takata , linux-mips@linux-mips.org, parisc-linux@parisc-linux.org, linuxppc-dev@ozlabs.org, linuxsh-dev@lists.sourceforge.net, linuxsh-shmedia-dev@lists.sourceforge.net, sparclinux@vger.kernel.org, ultralinux@vger.kernel.org, Chris Zankel , Akinobu Mita Subject: [patch 07/47] generic __{,test_and_}{set,clear,change}_bit() and test_bit() Content-Disposition: inline; filename=non-atomic-bitops.patch Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 10433 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: mita@miraclelinux.com Precedence: bulk X-list: linux-mips This patch introduces the C-language equivalents of the functions below: void __set_bit(int nr, volatile unsigned long *addr); void __clear_bit(int nr, volatile unsigned long *addr); void __change_bit(int nr, volatile unsigned long *addr); int __test_and_set_bit(int nr, volatile unsigned long *addr); int __test_and_clear_bit(int nr, volatile unsigned long *addr); int __test_and_change_bit(int nr, volatile unsigned long *addr); int test_bit(int nr, const volatile unsigned long *addr); In include/asm-generic/bitops/non-atomic.h This code largely copied from: asm-powerpc/bitops.h Signed-off-by: Akinobu Mita include/asm-generic/bitops/non-atomic.h | 111 ++++++++++++++++++++++++++++++++ 1 files changed, 111 insertions(+) Index: 2.6-rc/include/asm-generic/bitops/non-atomic.h =================================================================== --- /dev/null +++ 2.6-rc/include/asm-generic/bitops/non-atomic.h @@ -0,0 +1,111 @@ +#ifndef _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ +#define _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ + +#include + +#define BITOP_MASK(nr) (1UL << ((nr) % BITS_PER_LONG)) +#define BITOP_WORD(nr) ((nr) / BITS_PER_LONG) + +/** + * __set_bit - Set a bit in memory + * @nr: the bit to set + * @addr: the address to start counting from + * + * Unlike set_bit(), this function is non-atomic and may be reordered. + * If it's called on the same region of memory simultaneously, the effect + * may be that only one operation succeeds. + */ +static inline void __set_bit(int nr, volatile unsigned long *addr) +{ + unsigned long mask = BITOP_MASK(nr); + unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); + + *p |= mask; +} + +static inline void __clear_bit(int nr, volatile unsigned long *addr) +{ + unsigned long mask = BITOP_MASK(nr); + unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); + + *p &= ~mask; +} + +/** + * __change_bit - Toggle a bit in memory + * @nr: the bit to change + * @addr: the address to start counting from + * + * Unlike change_bit(), this function is non-atomic and may be reordered. + * If it's called on the same region of memory simultaneously, the effect + * may be that only one operation succeeds. + */ +static inline void __change_bit(int nr, volatile unsigned long *addr) +{ + unsigned long mask = BITOP_MASK(nr); + unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); + + *p ^= mask; +} + +/** + * __test_and_set_bit - Set a bit and return its old value + * @nr: Bit to set + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static inline int __test_and_set_bit(int nr, volatile unsigned long *addr) +{ + unsigned long mask = BITOP_MASK(nr); + unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); + unsigned long old = *p; + + *p = old | mask; + return (old & mask) != 0; +} + +/** + * __test_and_clear_bit - Clear a bit and return its old value + * @nr: Bit to clear + * @addr: Address to count from + * + * This operation is non-atomic and can be reordered. + * If two examples of this operation race, one can appear to succeed + * but actually fail. You must protect multiple accesses with a lock. + */ +static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr) +{ + unsigned long mask = BITOP_MASK(nr); + unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); + unsigned long old = *p; + + *p = old & ~mask; + return (old & mask) != 0; +} + +/* WARNING: non atomic and it can be reordered! */ +static inline int __test_and_change_bit(int nr, + volatile unsigned long *addr) +{ + unsigned long mask = BITOP_MASK(nr); + unsigned long *p = ((unsigned long *)addr) + BITOP_WORD(nr); + unsigned long old = *p; + + *p = old ^ mask; + return (old & mask) != 0; +} + +/** + * test_bit - Determine whether a bit is set + * @nr: bit number to test + * @addr: Address to start counting from + */ +static inline int test_bit(int nr, const volatile unsigned long *addr) +{ + return 1UL & (addr[BITOP_WORD(nr)] >> (nr & (BITS_PER_LONG-1))); +} + +#endif /* _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ */ --