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android_kernel_motorola_sm6225/include/linux/percpu-defs.h
Tejun Heo 3b8ed91d64 percpu: reorganize include/linux/percpu-defs.h 
Reorganize for better readability.

* Accessor definitions are collected into one place and SMP and UP now
  define them in the same order.

* Definitions are layered when possible - e.g. per_cpu() is now
  defined in terms of this_cpu_ptr().

* Rather pointless comment dropped.

* per_cpu(), __raw_get_cpu_var() and __get_cpu_var() are defined in a
  way which can be shared between SMP and UP and moved out of
  CONFIG_SMP blocks.

This patch doesn't introduce any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
2014-06-17 19:12:37 -04:00

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/*
* linux/percpu-defs.h - basic definitions for percpu areas
*
* DO NOT INCLUDE DIRECTLY OUTSIDE PERCPU IMPLEMENTATION PROPER.
*
* This file is separate from linux/percpu.h to avoid cyclic inclusion
* dependency from arch header files. Only to be included from
* asm/percpu.h.
*
* This file includes macros necessary to declare percpu sections and
* variables, and definitions of percpu accessors and operations. It
* should provide enough percpu features to arch header files even when
* they can only include asm/percpu.h to avoid cyclic inclusion dependency.
*/
#ifndef _LINUX_PERCPU_DEFS_H
#define _LINUX_PERCPU_DEFS_H
#ifdef CONFIG_SMP
#ifdef MODULE
#define PER_CPU_SHARED_ALIGNED_SECTION ""
#define PER_CPU_ALIGNED_SECTION ""
#else
#define PER_CPU_SHARED_ALIGNED_SECTION "..shared_aligned"
#define PER_CPU_ALIGNED_SECTION "..shared_aligned"
#endif
#define PER_CPU_FIRST_SECTION "..first"
#else
#define PER_CPU_SHARED_ALIGNED_SECTION ""
#define PER_CPU_ALIGNED_SECTION "..shared_aligned"
#define PER_CPU_FIRST_SECTION ""
#endif
/*
* Base implementations of per-CPU variable declarations and definitions, where
* the section in which the variable is to be placed is provided by the
* 'sec' argument. This may be used to affect the parameters governing the
* variable's storage.
*
* NOTE! The sections for the DECLARE and for the DEFINE must match, lest
* linkage errors occur due the compiler generating the wrong code to access
* that section.
*/
#define __PCPU_ATTRS(sec) \
__percpu __attribute__((section(PER_CPU_BASE_SECTION sec))) \
PER_CPU_ATTRIBUTES
#define __PCPU_DUMMY_ATTRS \
__attribute__((section(".discard"), unused))
/*
* Macro which verifies @ptr is a percpu pointer without evaluating
* @ptr. This is to be used in percpu accessors to verify that the
* input parameter is a percpu pointer.
*
* + 0 is required in order to convert the pointer type from a
* potential array type to a pointer to a single item of the array.
*/
#define __verify_pcpu_ptr(ptr) do { \
const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \
(void)__vpp_verify; \
} while (0)
/*
* s390 and alpha modules require percpu variables to be defined as
* weak to force the compiler to generate GOT based external
* references for them. This is necessary because percpu sections
* will be located outside of the usually addressable area.
*
* This definition puts the following two extra restrictions when
* defining percpu variables.
*
* 1. The symbol must be globally unique, even the static ones.
* 2. Static percpu variables cannot be defined inside a function.
*
* Archs which need weak percpu definitions should define
* ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary.
*
* To ensure that the generic code observes the above two
* restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak
* definition is used for all cases.
*/
#if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU)
/*
* __pcpu_scope_* dummy variable is used to enforce scope. It
* receives the static modifier when it's used in front of
* DEFINE_PER_CPU() and will trigger build failure if
* DECLARE_PER_CPU() is used for the same variable.
*
* __pcpu_unique_* dummy variable is used to enforce symbol uniqueness
* such that hidden weak symbol collision, which will cause unrelated
* variables to share the same address, can be detected during build.
*/
#define DECLARE_PER_CPU_SECTION(type, name, sec) \
extern __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
extern __PCPU_ATTRS(sec) __typeof__(type) name
#define DEFINE_PER_CPU_SECTION(type, name, sec) \
__PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \
__PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \
extern __PCPU_ATTRS(sec) __typeof__(type) name; \
__PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \
__typeof__(type) name
#else
/*
* Normal declaration and definition macros.
*/
#define DECLARE_PER_CPU_SECTION(type, name, sec) \
extern __PCPU_ATTRS(sec) __typeof__(type) name
#define DEFINE_PER_CPU_SECTION(type, name, sec) \
__PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES \
__typeof__(type) name
#endif
/*
* Variant on the per-CPU variable declaration/definition theme used for
* ordinary per-CPU variables.
*/
#define DECLARE_PER_CPU(type, name) \
DECLARE_PER_CPU_SECTION(type, name, "")
#define DEFINE_PER_CPU(type, name) \
DEFINE_PER_CPU_SECTION(type, name, "")
/*
* Declaration/definition used for per-CPU variables that must come first in
* the set of variables.
*/
#define DECLARE_PER_CPU_FIRST(type, name) \
DECLARE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
#define DEFINE_PER_CPU_FIRST(type, name) \
DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
/*
* Declaration/definition used for per-CPU variables that must be cacheline
* aligned under SMP conditions so that, whilst a particular instance of the
* data corresponds to a particular CPU, inefficiencies due to direct access by
* other CPUs are reduced by preventing the data from unnecessarily spanning
* cachelines.
*
* An example of this would be statistical data, where each CPU's set of data
* is updated by that CPU alone, but the data from across all CPUs is collated
* by a CPU processing a read from a proc file.
*/
#define DECLARE_PER_CPU_SHARED_ALIGNED(type, name) \
DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
____cacheline_aligned_in_smp
#define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \
DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
____cacheline_aligned_in_smp
#define DECLARE_PER_CPU_ALIGNED(type, name) \
DECLARE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
____cacheline_aligned
#define DEFINE_PER_CPU_ALIGNED(type, name) \
DEFINE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
____cacheline_aligned
/*
* Declaration/definition used for per-CPU variables that must be page aligned.
*/
#define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \
DECLARE_PER_CPU_SECTION(type, name, "..page_aligned") \
__aligned(PAGE_SIZE)
#define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
DEFINE_PER_CPU_SECTION(type, name, "..page_aligned") \
__aligned(PAGE_SIZE)
/*
* Declaration/definition used for per-CPU variables that must be read mostly.
*/
#define DECLARE_PER_CPU_READ_MOSTLY(type, name) \
DECLARE_PER_CPU_SECTION(type, name, "..readmostly")
#define DEFINE_PER_CPU_READ_MOSTLY(type, name) \
DEFINE_PER_CPU_SECTION(type, name, "..readmostly")
/*
* Intermodule exports for per-CPU variables. sparse forgets about
* address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to
* noop if __CHECKER__.
*/
#ifndef __CHECKER__
#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var)
#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var)
#else
#define EXPORT_PER_CPU_SYMBOL(var)
#define EXPORT_PER_CPU_SYMBOL_GPL(var)
#endif
/*
* Accessors and operations.
*/
#ifndef __ASSEMBLY__
#ifdef CONFIG_SMP
/*
* Add an offset to a pointer but keep the pointer as-is. Use RELOC_HIDE()
* to prevent the compiler from making incorrect assumptions about the
* pointer value. The weird cast keeps both GCC and sparse happy.
*/
#define SHIFT_PERCPU_PTR(__p, __offset) ({ \
__verify_pcpu_ptr((__p)); \
RELOC_HIDE((typeof(*(__p)) __kernel __force *)(__p), (__offset)); \
})
#define per_cpu_ptr(ptr, cpu) SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu)))
#define raw_cpu_ptr(ptr) arch_raw_cpu_ptr(ptr)
#ifdef CONFIG_DEBUG_PREEMPT
#define this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, my_cpu_offset)
#else
#define this_cpu_ptr(ptr) raw_cpu_ptr(ptr)
#endif
#else /* CONFIG_SMP */
#define VERIFY_PERCPU_PTR(__p) ({ \
__verify_pcpu_ptr((__p)); \
(typeof(*(__p)) __kernel __force *)(__p); \
})
#define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); VERIFY_PERCPU_PTR((ptr)); })
#define raw_cpu_ptr(ptr) per_cpu_ptr(ptr, 0)
#define this_cpu_ptr(ptr) raw_cpu_ptr(ptr)
#endif /* CONFIG_SMP */
#define per_cpu(var, cpu) (*per_cpu_ptr(&(var), cpu))
#define __raw_get_cpu_var(var) (*raw_cpu_ptr(&(var)))
#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
/* keep until we have removed all uses of __this_cpu_ptr */
#define __this_cpu_ptr(ptr) raw_cpu_ptr(ptr)
/*
* Must be an lvalue. Since @var must be a simple identifier,
* we force a syntax error here if it isn't.
*/
#define get_cpu_var(var) (*({ \
preempt_disable(); \
this_cpu_ptr(&var); }))
/*
* The weird & is necessary because sparse considers (void)(var) to be
* a direct dereference of percpu variable (var).
*/
#define put_cpu_var(var) do { \
(void)&(var); \
preempt_enable(); \
} while (0)
#define get_cpu_ptr(var) ({ \
preempt_disable(); \
this_cpu_ptr(var); })
#define put_cpu_ptr(var) do { \
(void)(var); \
preempt_enable(); \
} while (0)
#endif /* __ASSEMBLY__ */
#endif /* _LINUX_PERCPU_DEFS_H */
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