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authorDavid Howells <dhowells@redhat.com>2009-04-21 18:00:29 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-21 22:40:00 -0400
commit5028eaa97dd1dab9cd7c30c4d38f71c708ca64bc (patch)
treeff416e9ecb00ab2b616bce6acc4e2579c45b06b9
parent9b8de7479d0dbab1ed98b5b015d44232c9d3d08e (diff)
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>
-rw-r--r--include/asm-generic/percpu.h26
-rw-r--r--include/linux/percpu-defs.h84
-rw-r--r--include/linux/percpu.h20
3 files changed, 86 insertions, 44 deletions
diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
index af47b9e10064..d7d50d7ee51e 100644
--- a/include/asm-generic/percpu.h
+++ b/include/asm-generic/percpu.h
@@ -1,13 +1,9 @@
1#ifndef _ASM_GENERIC_PERCPU_H_ 1#ifndef _ASM_GENERIC_PERCPU_H_
2#define _ASM_GENERIC_PERCPU_H_ 2#define _ASM_GENERIC_PERCPU_H_
3
3#include <linux/compiler.h> 4#include <linux/compiler.h>
4#include <linux/threads.h> 5#include <linux/threads.h>
5 6#include <linux/percpu-defs.h>
6/*
7 * Determine the real variable name from the name visible in the
8 * kernel sources.
9 */
10#define per_cpu_var(var) per_cpu__##var
11 7
12#ifdef CONFIG_SMP 8#ifdef CONFIG_SMP
13 9
@@ -101,22 +97,4 @@ extern void setup_per_cpu_areas(void);
101#define PER_CPU_ATTRIBUTES 97#define PER_CPU_ATTRIBUTES
102#endif 98#endif
103 99
104#define DECLARE_PER_CPU_SECTION(type, name, section) \
105 extern \
106 __attribute__((__section__(PER_CPU_BASE_SECTION section))) \
107 PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
108
109#define DECLARE_PER_CPU(type, name) \
110 DECLARE_PER_CPU_SECTION(type, name, "")
111
112#define DECLARE_PER_CPU_SHARED_ALIGNED(type, name) \
113 DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
114 ____cacheline_aligned_in_smp
115
116#define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \
117 DECLARE_PER_CPU_SECTION(type, name, ".page_aligned")
118
119#define DECLARE_PER_CPU_FIRST(type, name) \
120 DECLARE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
121
122#endif /* _ASM_GENERIC_PERCPU_H_ */ 100#endif /* _ASM_GENERIC_PERCPU_H_ */
diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
new file mode 100644
index 000000000000..8f921d74f49f
--- /dev/null
+++ b/include/linux/percpu-defs.h
@@ -0,0 +1,84 @@
1#ifndef _LINUX_PERCPU_DEFS_H
2#define _LINUX_PERCPU_DEFS_H
3
4/*
5 * Determine the real variable name from the name visible in the
6 * kernel sources.
7 */
8#define per_cpu_var(var) per_cpu__##var
9
10/*
11 * Base implementations of per-CPU variable declarations and definitions, where
12 * the section in which the variable is to be placed is provided by the
13 * 'section' argument. This may be used to affect the parameters governing the
14 * variable's storage.
15 *
16 * NOTE! The sections for the DECLARE and for the DEFINE must match, lest
17 * linkage errors occur due the compiler generating the wrong code to access
18 * that section.
19 */
20#define DECLARE_PER_CPU_SECTION(type, name, section) \
21 extern \
22 __attribute__((__section__(PER_CPU_BASE_SECTION section))) \
23 PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
24
25#define DEFINE_PER_CPU_SECTION(type, name, section) \
26 __attribute__((__section__(PER_CPU_BASE_SECTION section))) \
27 PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
28
29/*
30 * Variant on the per-CPU variable declaration/definition theme used for
31 * ordinary per-CPU variables.
32 */
33#define DECLARE_PER_CPU(type, name) \
34 DECLARE_PER_CPU_SECTION(type, name, "")
35
36#define DEFINE_PER_CPU(type, name) \
37 DEFINE_PER_CPU_SECTION(type, name, "")
38
39/*
40 * Declaration/definition used for per-CPU variables that must come first in
41 * the set of variables.
42 */
43#define DECLARE_PER_CPU_FIRST(type, name) \
44 DECLARE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
45
46#define DEFINE_PER_CPU_FIRST(type, name) \
47 DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
48
49/*
50 * Declaration/definition used for per-CPU variables that must be cacheline
51 * aligned under SMP conditions so that, whilst a particular instance of the
52 * data corresponds to a particular CPU, inefficiencies due to direct access by
53 * other CPUs are reduced by preventing the data from unnecessarily spanning
54 * cachelines.
55 *
56 * An example of this would be statistical data, where each CPU's set of data
57 * is updated by that CPU alone, but the data from across all CPUs is collated
58 * by a CPU processing a read from a proc file.
59 */
60#define DECLARE_PER_CPU_SHARED_ALIGNED(type, name) \
61 DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
62 ____cacheline_aligned_in_smp
63
64#define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \
65 DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
66 ____cacheline_aligned_in_smp
67
68/*
69 * Declaration/definition used for per-CPU variables that must be page aligned.
70 */
71#define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \
72 DECLARE_PER_CPU_SECTION(type, name, ".page_aligned")
73
74#define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
75 DEFINE_PER_CPU_SECTION(type, name, ".page_aligned")
76
77/*
78 * Intermodule exports for per-CPU variables.
79 */
80#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var)
81#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var)
82
83
84#endif /* _LINUX_PERCPU_DEFS_H */
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index f052d8184993..1581ff235c7e 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -9,26 +9,6 @@
9 9
10#include <asm/percpu.h> 10#include <asm/percpu.h>
11 11
12#define DEFINE_PER_CPU_SECTION(type, name, section) \
13 __attribute__((__section__(PER_CPU_BASE_SECTION section))) \
14 PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
15
16#define DEFINE_PER_CPU(type, name) \
17 DEFINE_PER_CPU_SECTION(type, name, "")
18
19#define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \
20 DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
21 ____cacheline_aligned_in_smp
22
23#define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
24 DEFINE_PER_CPU_SECTION(type, name, ".page_aligned")
25
26#define DEFINE_PER_CPU_FIRST(type, name) \
27 DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
28
29#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var)
30#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var)
31
32/* enough to cover all DEFINE_PER_CPUs in modules */ 12/* enough to cover all DEFINE_PER_CPUs in modules */
33#ifdef CONFIG_MODULES 13#ifdef CONFIG_MODULES
34#define PERCPU_MODULE_RESERVE (8 << 10) 14#define PERCPU_MODULE_RESERVE (8 << 10)