x86: make pda a percpu variable

[ Based on original patch from Christoph Lameter and Mike Travis. ]

As pda is now allocated in percpu area, it can easily be made a proper
percpu variable.  Make it so by defining per cpu symbol from linker
script and declaring it in C code for SMP and simply defining it for
UP.  This change cleans up code and brings SMP and UP closer a bit.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/x86/include/asm/pda.h b/arch/x86/include/asm/pda.h
index e91558e37850..66ae1043393d 100644
--- a/arch/x86/include/asm/pda.h
+++ b/arch/x86/include/asm/pda.h
@@ -7,6 +7,7 @@
 #include <linux/cache.h>
 #include <linux/threads.h>
 #include <asm/page.h>
+#include <asm/percpu.h>
 
 /* Per processor datastructure. %gs points to it while the kernel runs */
 struct x8664_pda {
@@ -39,10 +40,10 @@ struct x8664_pda {
         unsigned irq_spurious_count;
 } ____cacheline_aligned_in_smp;
 
-extern struct x8664_pda *_cpu_pda[NR_CPUS];
+DECLARE_PER_CPU(struct x8664_pda, __pda);
 extern void pda_init(int);
 
-#define cpu_pda(i) (_cpu_pda[i])
+#define cpu_pda(cpu)            (&per_cpu(__pda, cpu))
 
 /*
  * There is no fast way to get the base address of the PDA, all the accesses