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![Mark Rutland](/assets/img/avatar_default.png)
As raw_cpu_generic_read() is a plain read from a raw_cpu_ptr() address, it's possible (albeit unlikely) that the compiler will split the access across multiple instructions. In this_cpu_generic_read() we disable preemption but not interrupts before calling raw_cpu_generic_read(). Thus, an interrupt could be taken in the middle of the split load instructions. If a this_cpu_write() or RMW this_cpu_*() op is made to the same variable in the interrupt handling path, this_cpu_read() will return a torn value. For native word types, we can avoid tearing using READ_ONCE(), but this won't work in all cases (e.g. 64-bit types on most 32-bit platforms). This patch reworks this_cpu_generic_read() to use READ_ONCE() where possible, otherwise falling back to disabling interrupts. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Lameter <cl@linux.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Pranith Kumar <bobby.prani@gmail.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Tejun Heo <tj@kernel.org>
447 lines
13 KiB
C
447 lines
13 KiB
C
#ifndef _ASM_GENERIC_PERCPU_H_
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#define _ASM_GENERIC_PERCPU_H_
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#include <linux/compiler.h>
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#include <linux/threads.h>
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#include <linux/percpu-defs.h>
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#ifdef CONFIG_SMP
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/*
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* per_cpu_offset() is the offset that has to be added to a
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* percpu variable to get to the instance for a certain processor.
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*
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* Most arches use the __per_cpu_offset array for those offsets but
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* some arches have their own ways of determining the offset (x86_64, s390).
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*/
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#ifndef __per_cpu_offset
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extern unsigned long __per_cpu_offset[NR_CPUS];
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#define per_cpu_offset(x) (__per_cpu_offset[x])
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#endif
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/*
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* Determine the offset for the currently active processor.
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* An arch may define __my_cpu_offset to provide a more effective
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* means of obtaining the offset to the per cpu variables of the
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* current processor.
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*/
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#ifndef __my_cpu_offset
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#define __my_cpu_offset per_cpu_offset(raw_smp_processor_id())
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#endif
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#ifdef CONFIG_DEBUG_PREEMPT
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#define my_cpu_offset per_cpu_offset(smp_processor_id())
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#else
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#define my_cpu_offset __my_cpu_offset
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#endif
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/*
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* Arch may define arch_raw_cpu_ptr() to provide more efficient address
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* translations for raw_cpu_ptr().
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*/
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#ifndef arch_raw_cpu_ptr
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#define arch_raw_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, __my_cpu_offset)
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#endif
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#ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
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extern void setup_per_cpu_areas(void);
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#endif
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#endif /* SMP */
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#ifndef PER_CPU_BASE_SECTION
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#ifdef CONFIG_SMP
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#define PER_CPU_BASE_SECTION ".data..percpu"
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#else
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#define PER_CPU_BASE_SECTION ".data"
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#endif
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#endif
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#ifndef PER_CPU_ATTRIBUTES
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#define PER_CPU_ATTRIBUTES
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#endif
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#ifndef PER_CPU_DEF_ATTRIBUTES
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#define PER_CPU_DEF_ATTRIBUTES
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#endif
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#define raw_cpu_generic_read(pcp) \
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({ \
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*raw_cpu_ptr(&(pcp)); \
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})
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#define raw_cpu_generic_to_op(pcp, val, op) \
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do { \
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*raw_cpu_ptr(&(pcp)) op val; \
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} while (0)
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#define raw_cpu_generic_add_return(pcp, val) \
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({ \
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typeof(&(pcp)) __p = raw_cpu_ptr(&(pcp)); \
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\
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*__p += val; \
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*__p; \
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})
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#define raw_cpu_generic_xchg(pcp, nval) \
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({ \
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typeof(&(pcp)) __p = raw_cpu_ptr(&(pcp)); \
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typeof(pcp) __ret; \
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__ret = *__p; \
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*__p = nval; \
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__ret; \
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})
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#define raw_cpu_generic_cmpxchg(pcp, oval, nval) \
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({ \
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typeof(&(pcp)) __p = raw_cpu_ptr(&(pcp)); \
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typeof(pcp) __ret; \
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__ret = *__p; \
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if (__ret == (oval)) \
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*__p = nval; \
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__ret; \
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})
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#define raw_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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({ \
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typeof(&(pcp1)) __p1 = raw_cpu_ptr(&(pcp1)); \
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typeof(&(pcp2)) __p2 = raw_cpu_ptr(&(pcp2)); \
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int __ret = 0; \
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if (*__p1 == (oval1) && *__p2 == (oval2)) { \
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*__p1 = nval1; \
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*__p2 = nval2; \
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__ret = 1; \
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} \
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(__ret); \
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})
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#define __this_cpu_generic_read_nopreempt(pcp) \
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({ \
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typeof(pcp) __ret; \
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preempt_disable_notrace(); \
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__ret = READ_ONCE(*raw_cpu_ptr(&(pcp))); \
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preempt_enable_notrace(); \
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__ret; \
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})
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#define __this_cpu_generic_read_noirq(pcp) \
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({ \
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typeof(pcp) __ret; \
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unsigned long __flags; \
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raw_local_irq_save(__flags); \
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__ret = raw_cpu_generic_read(pcp); \
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raw_local_irq_restore(__flags); \
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__ret; \
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})
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#define this_cpu_generic_read(pcp) \
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({ \
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typeof(pcp) __ret; \
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if (__native_word(pcp)) \
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__ret = __this_cpu_generic_read_nopreempt(pcp); \
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else \
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__ret = __this_cpu_generic_read_noirq(pcp); \
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__ret; \
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})
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#define this_cpu_generic_to_op(pcp, val, op) \
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do { \
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unsigned long __flags; \
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raw_local_irq_save(__flags); \
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raw_cpu_generic_to_op(pcp, val, op); \
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raw_local_irq_restore(__flags); \
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} while (0)
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#define this_cpu_generic_add_return(pcp, val) \
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({ \
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typeof(pcp) __ret; \
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unsigned long __flags; \
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raw_local_irq_save(__flags); \
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__ret = raw_cpu_generic_add_return(pcp, val); \
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raw_local_irq_restore(__flags); \
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__ret; \
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})
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#define this_cpu_generic_xchg(pcp, nval) \
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({ \
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typeof(pcp) __ret; \
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unsigned long __flags; \
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raw_local_irq_save(__flags); \
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__ret = raw_cpu_generic_xchg(pcp, nval); \
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raw_local_irq_restore(__flags); \
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__ret; \
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})
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#define this_cpu_generic_cmpxchg(pcp, oval, nval) \
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({ \
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typeof(pcp) __ret; \
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unsigned long __flags; \
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raw_local_irq_save(__flags); \
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__ret = raw_cpu_generic_cmpxchg(pcp, oval, nval); \
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raw_local_irq_restore(__flags); \
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__ret; \
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})
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#define this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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({ \
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int __ret; \
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unsigned long __flags; \
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raw_local_irq_save(__flags); \
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__ret = raw_cpu_generic_cmpxchg_double(pcp1, pcp2, \
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oval1, oval2, nval1, nval2); \
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raw_local_irq_restore(__flags); \
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__ret; \
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})
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#ifndef raw_cpu_read_1
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#define raw_cpu_read_1(pcp) raw_cpu_generic_read(pcp)
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#endif
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#ifndef raw_cpu_read_2
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#define raw_cpu_read_2(pcp) raw_cpu_generic_read(pcp)
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#endif
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#ifndef raw_cpu_read_4
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#define raw_cpu_read_4(pcp) raw_cpu_generic_read(pcp)
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#endif
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#ifndef raw_cpu_read_8
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#define raw_cpu_read_8(pcp) raw_cpu_generic_read(pcp)
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#endif
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#ifndef raw_cpu_write_1
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#define raw_cpu_write_1(pcp, val) raw_cpu_generic_to_op(pcp, val, =)
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#endif
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#ifndef raw_cpu_write_2
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#define raw_cpu_write_2(pcp, val) raw_cpu_generic_to_op(pcp, val, =)
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#endif
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#ifndef raw_cpu_write_4
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#define raw_cpu_write_4(pcp, val) raw_cpu_generic_to_op(pcp, val, =)
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#endif
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#ifndef raw_cpu_write_8
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#define raw_cpu_write_8(pcp, val) raw_cpu_generic_to_op(pcp, val, =)
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#endif
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#ifndef raw_cpu_add_1
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#define raw_cpu_add_1(pcp, val) raw_cpu_generic_to_op(pcp, val, +=)
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#endif
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#ifndef raw_cpu_add_2
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#define raw_cpu_add_2(pcp, val) raw_cpu_generic_to_op(pcp, val, +=)
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#endif
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#ifndef raw_cpu_add_4
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#define raw_cpu_add_4(pcp, val) raw_cpu_generic_to_op(pcp, val, +=)
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#endif
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#ifndef raw_cpu_add_8
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#define raw_cpu_add_8(pcp, val) raw_cpu_generic_to_op(pcp, val, +=)
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#endif
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#ifndef raw_cpu_and_1
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#define raw_cpu_and_1(pcp, val) raw_cpu_generic_to_op(pcp, val, &=)
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#endif
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#ifndef raw_cpu_and_2
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#define raw_cpu_and_2(pcp, val) raw_cpu_generic_to_op(pcp, val, &=)
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#endif
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#ifndef raw_cpu_and_4
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#define raw_cpu_and_4(pcp, val) raw_cpu_generic_to_op(pcp, val, &=)
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#endif
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#ifndef raw_cpu_and_8
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#define raw_cpu_and_8(pcp, val) raw_cpu_generic_to_op(pcp, val, &=)
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#endif
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#ifndef raw_cpu_or_1
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#define raw_cpu_or_1(pcp, val) raw_cpu_generic_to_op(pcp, val, |=)
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#endif
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#ifndef raw_cpu_or_2
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#define raw_cpu_or_2(pcp, val) raw_cpu_generic_to_op(pcp, val, |=)
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#endif
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#ifndef raw_cpu_or_4
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#define raw_cpu_or_4(pcp, val) raw_cpu_generic_to_op(pcp, val, |=)
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#endif
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#ifndef raw_cpu_or_8
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#define raw_cpu_or_8(pcp, val) raw_cpu_generic_to_op(pcp, val, |=)
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#endif
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#ifndef raw_cpu_add_return_1
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#define raw_cpu_add_return_1(pcp, val) raw_cpu_generic_add_return(pcp, val)
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#endif
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#ifndef raw_cpu_add_return_2
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#define raw_cpu_add_return_2(pcp, val) raw_cpu_generic_add_return(pcp, val)
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#endif
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#ifndef raw_cpu_add_return_4
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#define raw_cpu_add_return_4(pcp, val) raw_cpu_generic_add_return(pcp, val)
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#endif
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#ifndef raw_cpu_add_return_8
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#define raw_cpu_add_return_8(pcp, val) raw_cpu_generic_add_return(pcp, val)
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#endif
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#ifndef raw_cpu_xchg_1
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#define raw_cpu_xchg_1(pcp, nval) raw_cpu_generic_xchg(pcp, nval)
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#endif
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#ifndef raw_cpu_xchg_2
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#define raw_cpu_xchg_2(pcp, nval) raw_cpu_generic_xchg(pcp, nval)
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#endif
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#ifndef raw_cpu_xchg_4
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#define raw_cpu_xchg_4(pcp, nval) raw_cpu_generic_xchg(pcp, nval)
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#endif
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#ifndef raw_cpu_xchg_8
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#define raw_cpu_xchg_8(pcp, nval) raw_cpu_generic_xchg(pcp, nval)
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#endif
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#ifndef raw_cpu_cmpxchg_1
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#define raw_cpu_cmpxchg_1(pcp, oval, nval) \
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raw_cpu_generic_cmpxchg(pcp, oval, nval)
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#endif
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#ifndef raw_cpu_cmpxchg_2
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#define raw_cpu_cmpxchg_2(pcp, oval, nval) \
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raw_cpu_generic_cmpxchg(pcp, oval, nval)
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#endif
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#ifndef raw_cpu_cmpxchg_4
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#define raw_cpu_cmpxchg_4(pcp, oval, nval) \
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raw_cpu_generic_cmpxchg(pcp, oval, nval)
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#endif
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#ifndef raw_cpu_cmpxchg_8
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#define raw_cpu_cmpxchg_8(pcp, oval, nval) \
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raw_cpu_generic_cmpxchg(pcp, oval, nval)
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#endif
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#ifndef raw_cpu_cmpxchg_double_1
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#define raw_cpu_cmpxchg_double_1(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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raw_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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#endif
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#ifndef raw_cpu_cmpxchg_double_2
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#define raw_cpu_cmpxchg_double_2(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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raw_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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#endif
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#ifndef raw_cpu_cmpxchg_double_4
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#define raw_cpu_cmpxchg_double_4(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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raw_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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#endif
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#ifndef raw_cpu_cmpxchg_double_8
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#define raw_cpu_cmpxchg_double_8(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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raw_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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#endif
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#ifndef this_cpu_read_1
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#define this_cpu_read_1(pcp) this_cpu_generic_read(pcp)
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#endif
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#ifndef this_cpu_read_2
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#define this_cpu_read_2(pcp) this_cpu_generic_read(pcp)
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#endif
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#ifndef this_cpu_read_4
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#define this_cpu_read_4(pcp) this_cpu_generic_read(pcp)
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#endif
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#ifndef this_cpu_read_8
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#define this_cpu_read_8(pcp) this_cpu_generic_read(pcp)
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#endif
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#ifndef this_cpu_write_1
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#define this_cpu_write_1(pcp, val) this_cpu_generic_to_op(pcp, val, =)
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#endif
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#ifndef this_cpu_write_2
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#define this_cpu_write_2(pcp, val) this_cpu_generic_to_op(pcp, val, =)
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#endif
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#ifndef this_cpu_write_4
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#define this_cpu_write_4(pcp, val) this_cpu_generic_to_op(pcp, val, =)
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#endif
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#ifndef this_cpu_write_8
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#define this_cpu_write_8(pcp, val) this_cpu_generic_to_op(pcp, val, =)
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#endif
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#ifndef this_cpu_add_1
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#define this_cpu_add_1(pcp, val) this_cpu_generic_to_op(pcp, val, +=)
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#endif
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#ifndef this_cpu_add_2
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#define this_cpu_add_2(pcp, val) this_cpu_generic_to_op(pcp, val, +=)
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#endif
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#ifndef this_cpu_add_4
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#define this_cpu_add_4(pcp, val) this_cpu_generic_to_op(pcp, val, +=)
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#endif
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#ifndef this_cpu_add_8
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#define this_cpu_add_8(pcp, val) this_cpu_generic_to_op(pcp, val, +=)
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#endif
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#ifndef this_cpu_and_1
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#define this_cpu_and_1(pcp, val) this_cpu_generic_to_op(pcp, val, &=)
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#endif
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#ifndef this_cpu_and_2
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#define this_cpu_and_2(pcp, val) this_cpu_generic_to_op(pcp, val, &=)
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#endif
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#ifndef this_cpu_and_4
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#define this_cpu_and_4(pcp, val) this_cpu_generic_to_op(pcp, val, &=)
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#endif
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#ifndef this_cpu_and_8
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#define this_cpu_and_8(pcp, val) this_cpu_generic_to_op(pcp, val, &=)
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#endif
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#ifndef this_cpu_or_1
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#define this_cpu_or_1(pcp, val) this_cpu_generic_to_op(pcp, val, |=)
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#endif
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#ifndef this_cpu_or_2
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#define this_cpu_or_2(pcp, val) this_cpu_generic_to_op(pcp, val, |=)
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#endif
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#ifndef this_cpu_or_4
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#define this_cpu_or_4(pcp, val) this_cpu_generic_to_op(pcp, val, |=)
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#endif
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#ifndef this_cpu_or_8
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#define this_cpu_or_8(pcp, val) this_cpu_generic_to_op(pcp, val, |=)
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#endif
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#ifndef this_cpu_add_return_1
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#define this_cpu_add_return_1(pcp, val) this_cpu_generic_add_return(pcp, val)
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#endif
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#ifndef this_cpu_add_return_2
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#define this_cpu_add_return_2(pcp, val) this_cpu_generic_add_return(pcp, val)
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#endif
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#ifndef this_cpu_add_return_4
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#define this_cpu_add_return_4(pcp, val) this_cpu_generic_add_return(pcp, val)
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#endif
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#ifndef this_cpu_add_return_8
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#define this_cpu_add_return_8(pcp, val) this_cpu_generic_add_return(pcp, val)
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#endif
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#ifndef this_cpu_xchg_1
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#define this_cpu_xchg_1(pcp, nval) this_cpu_generic_xchg(pcp, nval)
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#endif
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#ifndef this_cpu_xchg_2
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#define this_cpu_xchg_2(pcp, nval) this_cpu_generic_xchg(pcp, nval)
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#endif
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#ifndef this_cpu_xchg_4
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#define this_cpu_xchg_4(pcp, nval) this_cpu_generic_xchg(pcp, nval)
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#endif
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#ifndef this_cpu_xchg_8
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#define this_cpu_xchg_8(pcp, nval) this_cpu_generic_xchg(pcp, nval)
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#endif
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#ifndef this_cpu_cmpxchg_1
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#define this_cpu_cmpxchg_1(pcp, oval, nval) \
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this_cpu_generic_cmpxchg(pcp, oval, nval)
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#endif
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#ifndef this_cpu_cmpxchg_2
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#define this_cpu_cmpxchg_2(pcp, oval, nval) \
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this_cpu_generic_cmpxchg(pcp, oval, nval)
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#endif
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#ifndef this_cpu_cmpxchg_4
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#define this_cpu_cmpxchg_4(pcp, oval, nval) \
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this_cpu_generic_cmpxchg(pcp, oval, nval)
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#endif
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#ifndef this_cpu_cmpxchg_8
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#define this_cpu_cmpxchg_8(pcp, oval, nval) \
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this_cpu_generic_cmpxchg(pcp, oval, nval)
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#endif
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#ifndef this_cpu_cmpxchg_double_1
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#define this_cpu_cmpxchg_double_1(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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#endif
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#ifndef this_cpu_cmpxchg_double_2
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#define this_cpu_cmpxchg_double_2(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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#endif
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#ifndef this_cpu_cmpxchg_double_4
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#define this_cpu_cmpxchg_double_4(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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#endif
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#ifndef this_cpu_cmpxchg_double_8
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#define this_cpu_cmpxchg_double_8(pcp1, pcp2, oval1, oval2, nval1, nval2) \
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this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
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#endif
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#endif /* _ASM_GENERIC_PERCPU_H_ */
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