1af5de9af1
Implement FETCH-OP atomic primitives, these are very similar to the existing OP-RETURN primitives we already have, except they return the value of the atomic variable _before_ modification. This is especially useful for irreversible operations -- such as bitops (because it becomes impossible to reconstruct the state prior to modification). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Chris Metcalf <cmetcalf@mellanox.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
127 lines
4.0 KiB
C
127 lines
4.0 KiB
C
/*
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* Copyright 2010 Tilera Corporation. All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation, version 2.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for
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* more details.
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*/
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#ifndef _ASM_TILE_BITOPS_32_H
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#define _ASM_TILE_BITOPS_32_H
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#include <linux/compiler.h>
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#include <asm/barrier.h>
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/* Tile-specific routines to support <asm/bitops.h>. */
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unsigned long _atomic_fetch_or(volatile unsigned long *p, unsigned long mask);
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unsigned long _atomic_fetch_andn(volatile unsigned long *p, unsigned long mask);
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unsigned long _atomic_fetch_xor(volatile unsigned long *p, unsigned long mask);
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/**
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* set_bit - Atomically set a bit in memory
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* @nr: the bit to set
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* @addr: the address to start counting from
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*
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* This function is atomic and may not be reordered.
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* See __set_bit() if you do not require the atomic guarantees.
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* Note that @nr may be almost arbitrarily large; this function is not
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* restricted to acting on a single-word quantity.
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*/
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static inline void set_bit(unsigned nr, volatile unsigned long *addr)
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{
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_atomic_fetch_or(addr + BIT_WORD(nr), BIT_MASK(nr));
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}
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/**
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* clear_bit - Clears a bit in memory
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* @nr: Bit to clear
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* @addr: Address to start counting from
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*
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* clear_bit() is atomic and may not be reordered.
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* See __clear_bit() if you do not require the atomic guarantees.
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* Note that @nr may be almost arbitrarily large; this function is not
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* restricted to acting on a single-word quantity.
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*
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* clear_bit() may not contain a memory barrier, so if it is used for
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* locking purposes, you should call smp_mb__before_atomic() and/or
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* smp_mb__after_atomic() to ensure changes are visible on other cpus.
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*/
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static inline void clear_bit(unsigned nr, volatile unsigned long *addr)
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{
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_atomic_fetch_andn(addr + BIT_WORD(nr), BIT_MASK(nr));
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}
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/**
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* change_bit - Toggle a bit in memory
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* @nr: Bit to change
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* @addr: Address to start counting from
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*
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* change_bit() is atomic and may not be reordered.
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* See __change_bit() if you do not require the atomic guarantees.
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* Note that @nr may be almost arbitrarily large; this function is not
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* restricted to acting on a single-word quantity.
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*/
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static inline void change_bit(unsigned nr, volatile unsigned long *addr)
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{
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_atomic_fetch_xor(addr + BIT_WORD(nr), BIT_MASK(nr));
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}
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/**
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* test_and_set_bit - Set a bit and return its old value
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* @nr: Bit to set
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* @addr: Address to count from
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*
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* This operation is atomic and cannot be reordered.
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* It also implies a memory barrier.
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*/
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static inline int test_and_set_bit(unsigned nr, volatile unsigned long *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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addr += BIT_WORD(nr);
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smp_mb(); /* barrier for proper semantics */
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return (_atomic_fetch_or(addr, mask) & mask) != 0;
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}
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/**
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* test_and_clear_bit - Clear a bit and return its old value
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* @nr: Bit to clear
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* @addr: Address to count from
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*
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* This operation is atomic and cannot be reordered.
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* It also implies a memory barrier.
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*/
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static inline int test_and_clear_bit(unsigned nr, volatile unsigned long *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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addr += BIT_WORD(nr);
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smp_mb(); /* barrier for proper semantics */
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return (_atomic_fetch_andn(addr, mask) & mask) != 0;
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}
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/**
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* test_and_change_bit - Change a bit and return its old value
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* @nr: Bit to change
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* @addr: Address to count from
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*
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* This operation is atomic and cannot be reordered.
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* It also implies a memory barrier.
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*/
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static inline int test_and_change_bit(unsigned nr,
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volatile unsigned long *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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addr += BIT_WORD(nr);
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smp_mb(); /* barrier for proper semantics */
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return (_atomic_fetch_xor(addr, mask) & mask) != 0;
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}
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#include <asm-generic/bitops/ext2-atomic.h>
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#endif /* _ASM_TILE_BITOPS_32_H */
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