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authorTejun Heo <tj@kernel.org>2009-09-14 20:57:19 -0400
committerTejun Heo <tj@kernel.org>2009-09-14 20:57:19 -0400
commit5579fd7e6aed8860ea0c8e3f11897493153b10ad (patch)
tree8f797ccd0f1a2c88f1605ae9e90b3ac17485de27 /include/linux/percpu-defs.h
parent04a13c7c632e1fe04a5f6e6c83565d2559e37598 (diff)
parentc2a7e818019f20a5cf7fb26a6eb59e212e6c0cd8 (diff)
Merge branch 'for-next' into for-linus
* pcpu_chunk_page_occupied() doesn't exist in for-next. * pcpu_chunk_addr_search() updated to use raw_smp_processor_id(). Conflicts: mm/percpu.c
Diffstat (limited to 'include/linux/percpu-defs.h')
-rw-r--r--include/linux/percpu-defs.h66
1 files changed, 57 insertions, 9 deletions
diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index 68438e18fff4..aefc2f12b48c 100644
--- a/include/linux/percpu-defs.h
+++ b/include/linux/percpu-defs.h
@@ -10,22 +10,70 @@
10/* 10/*
11 * Base implementations of per-CPU variable declarations and definitions, where 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 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 13 * 'sec' argument. This may be used to affect the parameters governing the
14 * variable's storage. 14 * variable's storage.
15 * 15 *
16 * NOTE! The sections for the DECLARE and for the DEFINE must match, lest 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 17 * linkage errors occur due the compiler generating the wrong code to access
18 * that section. 18 * that section.
19 */ 19 */
20#define DECLARE_PER_CPU_SECTION(type, name, section) \ 20#define __PCPU_ATTRS(sec) \
21 extern \ 21 __attribute__((section(PER_CPU_BASE_SECTION sec))) \
22 __attribute__((__section__(PER_CPU_BASE_SECTION section))) \ 22 PER_CPU_ATTRIBUTES
23 PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name 23
24 24#define __PCPU_DUMMY_ATTRS \
25#define DEFINE_PER_CPU_SECTION(type, name, section) \ 25 __attribute__((section(".discard"), unused))
26 __attribute__((__section__(PER_CPU_BASE_SECTION section))) \ 26
27 PER_CPU_ATTRIBUTES PER_CPU_DEF_ATTRIBUTES \ 27/*
28 * s390 and alpha modules require percpu variables to be defined as
29 * weak to force the compiler to generate GOT based external
30 * references for them. This is necessary because percpu sections
31 * will be located outside of the usually addressable area.
32 *
33 * This definition puts the following two extra restrictions when
34 * defining percpu variables.
35 *
36 * 1. The symbol must be globally unique, even the static ones.
37 * 2. Static percpu variables cannot be defined inside a function.
38 *
39 * Archs which need weak percpu definitions should define
40 * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary.
41 *
42 * To ensure that the generic code observes the above two
43 * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak
44 * definition is used for all cases.
45 */
46#if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU)
47/*
48 * __pcpu_scope_* dummy variable is used to enforce scope. It
49 * receives the static modifier when it's used in front of
50 * DEFINE_PER_CPU() and will trigger build failure if
51 * DECLARE_PER_CPU() is used for the same variable.
52 *
53 * __pcpu_unique_* dummy variable is used to enforce symbol uniqueness
54 * such that hidden weak symbol collision, which will cause unrelated
55 * variables to share the same address, can be detected during build.
56 */
57#define DECLARE_PER_CPU_SECTION(type, name, sec) \
58 extern __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
59 extern __PCPU_ATTRS(sec) __typeof__(type) per_cpu__##name
60
61#define DEFINE_PER_CPU_SECTION(type, name, sec) \
62 __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
63 __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \
64 __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \
65 __typeof__(type) per_cpu__##name
66#else
67/*
68 * Normal declaration and definition macros.
69 */
70#define DECLARE_PER_CPU_SECTION(type, name, sec) \
71 extern __PCPU_ATTRS(sec) __typeof__(type) per_cpu__##name
72
73#define DEFINE_PER_CPU_SECTION(type, name, sec) \
74 __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES \
28 __typeof__(type) per_cpu__##name 75 __typeof__(type) per_cpu__##name
76#endif
29 77
30/* 78/*
31 * Variant on the per-CPU variable declaration/definition theme used for 79 * Variant on the per-CPU variable declaration/definition theme used for