PERCPU: Collect the DECLARE/DEFINE declarations together
Collect the DECLARE/DEFINE declarations together in linux/percpu-defs.h so that they're in one place, and give them descriptive comments, particularly the SHARED_ALIGNED variant. It would be nice to collect these in linux/percpu.h, but that's not possible without sorting out the severe #include recursion between the x86 arch headers and the general headers (and possibly other arches too). Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
9b8de7479d
commit
5028eaa97d
|
@ -1,13 +1,9 @@
|
|||
#ifndef _ASM_GENERIC_PERCPU_H_
|
||||
#define _ASM_GENERIC_PERCPU_H_
|
||||
|
||||
#include <linux/compiler.h>
|
||||
#include <linux/threads.h>
|
||||
|
||||
/*
|
||||
* Determine the real variable name from the name visible in the
|
||||
* kernel sources.
|
||||
*/
|
||||
#define per_cpu_var(var) per_cpu__##var
|
||||
#include <linux/percpu-defs.h>
|
||||
|
||||
#ifdef CONFIG_SMP
|
||||
|
||||
|
@ -101,22 +97,4 @@ extern void setup_per_cpu_areas(void);
|
|||
#define PER_CPU_ATTRIBUTES
|
||||
#endif
|
||||
|
||||
#define DECLARE_PER_CPU_SECTION(type, name, section) \
|
||||
extern \
|
||||
__attribute__((__section__(PER_CPU_BASE_SECTION section))) \
|
||||
PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
|
||||
|
||||
#define DECLARE_PER_CPU(type, name) \
|
||||
DECLARE_PER_CPU_SECTION(type, name, "")
|
||||
|
||||
#define DECLARE_PER_CPU_SHARED_ALIGNED(type, name) \
|
||||
DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
|
||||
____cacheline_aligned_in_smp
|
||||
|
||||
#define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \
|
||||
DECLARE_PER_CPU_SECTION(type, name, ".page_aligned")
|
||||
|
||||
#define DECLARE_PER_CPU_FIRST(type, name) \
|
||||
DECLARE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
|
||||
|
||||
#endif /* _ASM_GENERIC_PERCPU_H_ */
|
||||
|
|
84
include/linux/percpu-defs.h
Normal file
84
include/linux/percpu-defs.h
Normal file
|
@ -0,0 +1,84 @@
|
|||
#ifndef _LINUX_PERCPU_DEFS_H
|
||||
#define _LINUX_PERCPU_DEFS_H
|
||||
|
||||
/*
|
||||
* Determine the real variable name from the name visible in the
|
||||
* kernel sources.
|
||||
*/
|
||||
#define per_cpu_var(var) per_cpu__##var
|
||||
|
||||
/*
|
||||
* Base implementations of per-CPU variable declarations and definitions, where
|
||||
* the section in which the variable is to be placed is provided by the
|
||||
* 'section' 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 DECLARE_PER_CPU_SECTION(type, name, section) \
|
||||
extern \
|
||||
__attribute__((__section__(PER_CPU_BASE_SECTION section))) \
|
||||
PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
|
||||
|
||||
#define DEFINE_PER_CPU_SECTION(type, name, section) \
|
||||
__attribute__((__section__(PER_CPU_BASE_SECTION section))) \
|
||||
PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
|
||||
|
||||
/*
|
||||
* 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
|
||||
|
||||
/*
|
||||
* 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")
|
||||
|
||||
#define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
|
||||
DEFINE_PER_CPU_SECTION(type, name, ".page_aligned")
|
||||
|
||||
/*
|
||||
* Intermodule exports for per-CPU variables.
|
||||
*/
|
||||
#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var)
|
||||
#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var)
|
||||
|
||||
|
||||
#endif /* _LINUX_PERCPU_DEFS_H */
|
|
@ -9,26 +9,6 @@
|
|||
|
||||
#include <asm/percpu.h>
|
||||
|
||||
#define DEFINE_PER_CPU_SECTION(type, name, section) \
|
||||
__attribute__((__section__(PER_CPU_BASE_SECTION section))) \
|
||||
PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
|
||||
|
||||
#define DEFINE_PER_CPU(type, name) \
|
||||
DEFINE_PER_CPU_SECTION(type, name, "")
|
||||
|
||||
#define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \
|
||||
DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
|
||||
____cacheline_aligned_in_smp
|
||||
|
||||
#define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
|
||||
DEFINE_PER_CPU_SECTION(type, name, ".page_aligned")
|
||||
|
||||
#define DEFINE_PER_CPU_FIRST(type, name) \
|
||||
DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
|
||||
|
||||
#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var)
|
||||
#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var)
|
||||
|
||||
/* enough to cover all DEFINE_PER_CPUs in modules */
|
||||
#ifdef CONFIG_MODULES
|
||||
#define PERCPU_MODULE_RESERVE (8 << 10)
|
||||
|
|
Loading…
Reference in a new issue