releases/2.6.30.2/alpha-fix-percpu-build-breakage.patch

   1 From b01e8dc34379f4ba2f454390e340a025edbaaa7e Mon Sep 17 00:00:00 2001
   2 From: Tejun Heo <tj@kernel.org>
   3 Date: Tue, 30 Jun 2009 11:41:18 -0700
   4 Subject: alpha: fix percpu build breakage
   5
   6 From: Tejun Heo <tj@kernel.org>
   7
   8 commit b01e8dc34379f4ba2f454390e340a025edbaaa7e upstream.
   9
  10 alpha percpu access requires custom SHIFT_PERCPU_PTR() definition for
  11 modules to work around addressing range limitation.  This is done via
  12 generating inline assembly using C preprocessing which forces the
  13 assembler to generate external reference.  This happens behind the
  14 compiler's back and makes the compiler think that static percpu variables
  15 in modules are unused.
  16
  17 This used to be worked around by using __unused attribute for percpu
  18 variables which prevent the compiler from omitting the variable; however,
  19 recent declare/definition attribute unification change broke this as
  20 __used can't be used for declaration.  Also, in the process,
  21 PER_CPU_ATTRIBUTES definition in alpha percpu.h got broken.
  22
  23 This patch adds PER_CPU_DEF_ATTRIBUTES which is only used for definitions
  24 and make alpha use it to add __used for percpu variables in modules.  This
  25 also fixes the PER_CPU_ATTRIBUTES double definition bug.
  26
  27 Signed-off-by: Tejun Heo <tj@kernel.org>
  28 Tested-by: maximilian attems <max@stro.at>
  29 Acked-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
  30 Cc: Richard Henderson <rth@twiddle.net>
  31 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  32 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  33 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  34
  35 ---
  36  arch/alpha/include/asm/percpu.h |    6 +++---
  37  include/asm-generic/percpu.h    |    4 ++++
  38  include/linux/percpu-defs.h     |    3 ++-
  39  3 files changed, 9 insertions(+), 4 deletions(-)
  40
  41 --- a/arch/alpha/include/asm/percpu.h
  42 +++ b/arch/alpha/include/asm/percpu.h
  43 @@ -30,7 +30,7 @@ extern unsigned long __per_cpu_offset[NR
  44
  45  #ifndef MODULE
  46  #define SHIFT_PERCPU_PTR(var, offset) RELOC_HIDE(&per_cpu_var(var), (offset))
  47 -#define PER_CPU_ATTRIBUTES
  48 +#define PER_CPU_DEF_ATTRIBUTES
  49  #else
  50  /*
  51   * To calculate addresses of locally defined variables, GCC uses 32-bit
  52 @@ -49,7 +49,7 @@ extern unsigned long __per_cpu_offset[NR
  53                 : "=&r"(__ptr), "=&r"(tmp_gp));         \
  54         (typeof(&per_cpu_var(var)))(__ptr + (offset)); })
  55
  56 -#define PER_CPU_ATTRIBUTES     __used
  57 +#define PER_CPU_DEF_ATTRIBUTES __used
  58
  59  #endif /* MODULE */
  60
  61 @@ -71,7 +71,7 @@ extern unsigned long __per_cpu_offset[NR
  62  #define __get_cpu_var(var)             per_cpu_var(var)
  63  #define __raw_get_cpu_var(var)         per_cpu_var(var)
  64
  65 -#define PER_CPU_ATTRIBUTES
  66 +#define PER_CPU_DEF_ATTRIBUTES
  67
  68  #endif /* SMP */
  69
  70 --- a/include/asm-generic/percpu.h
  71 +++ b/include/asm-generic/percpu.h
  72 @@ -97,4 +97,8 @@ extern void setup_per_cpu_areas(void);
  73  #define PER_CPU_ATTRIBUTES
  74  #endif
  75
  76 +#ifndef PER_CPU_DEF_ATTRIBUTES
  77 +#define PER_CPU_DEF_ATTRIBUTES
  78 +#endif
  79 +
  80  #endif /* _ASM_GENERIC_PERCPU_H_ */
  81 --- a/include/linux/percpu-defs.h
  82 +++ b/include/linux/percpu-defs.h
  83 @@ -24,7 +24,8 @@
  84
  85  #define DEFINE_PER_CPU_SECTION(type, name, section)                    \
  86         __attribute__((__section__(PER_CPU_BASE_SECTION section)))      \
  87 -       PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
  88 +       PER_CPU_ATTRIBUTES PER_CPU_DEF_ATTRIBUTES                       \
  89 +       __typeof__(type) per_cpu__##name
  90
  91  /*
  92   * Variant on the per-CPU variable declaration/definition theme used for