[PATCH 2/3] x86,percpu: fix DECLARE/DEFINE_PER_CPU_PAGE_ALIGNED()

Tejun Heo
2009-08-03T05:10:36Z

DECLARE/DEFINE_PER_CPU_PAGE_ALIGNED() put percpu variables in
.page_aligned section without adding any alignment restrictions.
Currently, this doesn't cause any problem because all users of the
macros have explicit page alignment and page-sized but it's much safer
to enforce page alignment from the macros. After all, it's what they
claim to do.

Add __aligned(PAGE_SIZE) to DECLARE/DEFINE_PER_CPU_PAGE_ALIGNED() and
drop explicit alignment from it users.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
---
This doesn't cause any problem for the current tree. No need to push
it hastily.

arch/x86/kernel/cpu/common.c | 3 +--
include/linux/percpu-defs.h | 8 +++++---
2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index f1961c0..12493c5 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1008,8 +1008,7 @@ static const unsigned int exception_stack_sizes[N_EXCEPTION_STACKS] = {
};

static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks
- [(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ])
- __aligned(PAGE_SIZE);
+ [(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]);

/* May not be marked __init: used by software suspend */
void syscall_init(void)
diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index aefc2f1..18d3147 100644
--- a/include/linux/percpu-defs.h
+++ b/include/linux/percpu-defs.h
@@ -117,11 +117,13 @@
/*
* 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 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")
+ DEFINE_PER_CPU_SECTION(type, name, ".page_aligned") \
+ __aligned(PAGE_SIZE)

/*
* Intermodule exports for per-CPU variables.
--
1.6.0.2