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This patch makes sure that atomic_{read,set}() are at least
{READ,WRITE}_ONCE().
We already had the 'requirement' that atomic_read() should use
ACCESS_ONCE(), and most archs had this, but a few were lacking.
All are now converted to use READ_ONCE().
And, by a symmetry and general paranoia argument, upgrade atomic_set()
to use WRITE_ONCE().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
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: james.hogan@imgtec.com
Cc: linux-kernel@vger.kernel.org
Cc: oleg@redhat.com
Cc: will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
96 lines
3.1 KiB
C
96 lines
3.1 KiB
C
/*
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* Based on arch/arm/include/asm/atomic.h
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*
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* Copyright (C) 1996 Russell King.
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* Copyright (C) 2002 Deep Blue Solutions Ltd.
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __ASM_ATOMIC_H
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#define __ASM_ATOMIC_H
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#include <linux/compiler.h>
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#include <linux/types.h>
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#include <asm/barrier.h>
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#include <asm/lse.h>
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#ifdef __KERNEL__
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#define __ARM64_IN_ATOMIC_IMPL
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#if defined(CONFIG_ARM64_LSE_ATOMICS) && defined(CONFIG_AS_LSE)
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#include <asm/atomic_lse.h>
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#else
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#include <asm/atomic_ll_sc.h>
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#endif
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#undef __ARM64_IN_ATOMIC_IMPL
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#include <asm/cmpxchg.h>
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#define ___atomic_add_unless(v, a, u, sfx) \
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({ \
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typeof((v)->counter) c, old; \
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\
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c = atomic##sfx##_read(v); \
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while (c != (u) && \
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(old = atomic##sfx##_cmpxchg((v), c, c + (a))) != c) \
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c = old; \
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c; \
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})
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#define ATOMIC_INIT(i) { (i) }
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#define atomic_read(v) READ_ONCE((v)->counter)
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#define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
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#define atomic_xchg(v, new) xchg(&((v)->counter), (new))
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#define atomic_cmpxchg(v, old, new) cmpxchg(&((v)->counter), (old), (new))
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#define atomic_inc(v) atomic_add(1, (v))
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#define atomic_dec(v) atomic_sub(1, (v))
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#define atomic_inc_return(v) atomic_add_return(1, (v))
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#define atomic_dec_return(v) atomic_sub_return(1, (v))
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#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
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#define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
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#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
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#define atomic_add_negative(i, v) (atomic_add_return((i), (v)) < 0)
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#define __atomic_add_unless(v, a, u) ___atomic_add_unless(v, a, u,)
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#define atomic_andnot atomic_andnot
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/*
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* 64-bit atomic operations.
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*/
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#define ATOMIC64_INIT ATOMIC_INIT
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#define atomic64_read atomic_read
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#define atomic64_set atomic_set
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#define atomic64_xchg atomic_xchg
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#define atomic64_cmpxchg atomic_cmpxchg
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#define atomic64_inc(v) atomic64_add(1, (v))
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#define atomic64_dec(v) atomic64_sub(1, (v))
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#define atomic64_inc_return(v) atomic64_add_return(1, (v))
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#define atomic64_dec_return(v) atomic64_sub_return(1, (v))
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#define atomic64_inc_and_test(v) (atomic64_inc_return(v) == 0)
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#define atomic64_dec_and_test(v) (atomic64_dec_return(v) == 0)
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#define atomic64_sub_and_test(i, v) (atomic64_sub_return((i), (v)) == 0)
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#define atomic64_add_negative(i, v) (atomic64_add_return((i), (v)) < 0)
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#define atomic64_add_unless(v, a, u) (___atomic_add_unless(v, a, u, 64) != u)
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#define atomic64_andnot atomic64_andnot
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#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
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#endif
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#endif
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