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8fc4fddaf9
Implement generic support for local{,64}_try_cmpxchg().
Redirect to the atomic_ family of functions when the target
does not provide its own local.h definitions.
For 64-bit targets, implement local64_try_cmpxchg and
local64_cmpxchg using typed C wrappers that call local_
family of functions and provide additional checking
of their input arguments.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20230405141710.3551-3-ubizjak@gmail.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
57 lines
2.3 KiB
C
57 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_GENERIC_LOCAL_H
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#define _ASM_GENERIC_LOCAL_H
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#include <linux/percpu.h>
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#include <linux/atomic.h>
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#include <asm/types.h>
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/*
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* A signed long type for operations which are atomic for a single CPU.
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* Usually used in combination with per-cpu variables.
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*
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* This is the default implementation, which uses atomic_long_t. Which is
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* rather pointless. The whole point behind local_t is that some processors
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* can perform atomic adds and subtracts in a manner which is atomic wrt IRQs
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* running on this CPU. local_t allows exploitation of such capabilities.
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*/
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/* Implement in terms of atomics. */
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/* Don't use typedef: don't want them to be mixed with atomic_t's. */
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typedef struct
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{
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atomic_long_t a;
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} local_t;
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#define LOCAL_INIT(i) { ATOMIC_LONG_INIT(i) }
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#define local_read(l) atomic_long_read(&(l)->a)
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#define local_set(l,i) atomic_long_set((&(l)->a),(i))
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#define local_inc(l) atomic_long_inc(&(l)->a)
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#define local_dec(l) atomic_long_dec(&(l)->a)
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#define local_add(i,l) atomic_long_add((i),(&(l)->a))
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#define local_sub(i,l) atomic_long_sub((i),(&(l)->a))
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#define local_sub_and_test(i, l) atomic_long_sub_and_test((i), (&(l)->a))
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#define local_dec_and_test(l) atomic_long_dec_and_test(&(l)->a)
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#define local_inc_and_test(l) atomic_long_inc_and_test(&(l)->a)
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#define local_add_negative(i, l) atomic_long_add_negative((i), (&(l)->a))
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#define local_add_return(i, l) atomic_long_add_return((i), (&(l)->a))
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#define local_sub_return(i, l) atomic_long_sub_return((i), (&(l)->a))
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#define local_inc_return(l) atomic_long_inc_return(&(l)->a)
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#define local_cmpxchg(l, o, n) atomic_long_cmpxchg((&(l)->a), (o), (n))
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#define local_try_cmpxchg(l, po, n) atomic_long_try_cmpxchg((&(l)->a), (po), (n))
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#define local_xchg(l, n) atomic_long_xchg((&(l)->a), (n))
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#define local_add_unless(l, _a, u) atomic_long_add_unless((&(l)->a), (_a), (u))
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#define local_inc_not_zero(l) atomic_long_inc_not_zero(&(l)->a)
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/* Non-atomic variants, ie. preemption disabled and won't be touched
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* in interrupt, etc. Some archs can optimize this case well. */
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#define __local_inc(l) local_set((l), local_read(l) + 1)
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#define __local_dec(l) local_set((l), local_read(l) - 1)
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#define __local_add(i,l) local_set((l), local_read(l) + (i))
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#define __local_sub(i,l) local_set((l), local_read(l) - (i))
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#endif /* _ASM_GENERIC_LOCAL_H */
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