[PATCH] Define __raw_get_cpu_var and use it

There are several instances of per_cpu(foo, raw_smp_processor_id()), which
is semantically equivalent to __get_cpu_var(foo) but without the warning
that smp_processor_id() can give if CONFIG_DEBUG_PREEMPT is enabled.  For
those architectures with optimized per-cpu implementations, namely ia64,
powerpc, s390, sparc64 and x86_64, per_cpu() turns into more and slower
code than __get_cpu_var(), so it would be preferable to use __get_cpu_var
on those platforms.

This defines a __raw_get_cpu_var(x) macro which turns into per_cpu(x,
raw_smp_processor_id()) on architectures that use the generic per-cpu
implementation, and turns into __get_cpu_var(x) on the architectures that
have an optimized per-cpu implementation.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 5dbc42694477..f8d540b324ca 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4152,7 +4152,7 @@ EXPORT_SYMBOL(yield);
  */
 void __sched io_schedule(void)
 {
-        struct runqueue *rq = &per_cpu(runqueues, raw_smp_processor_id());
+        struct runqueue *rq = &__raw_get_cpu_var(runqueues);
 
         atomic_inc(&rq->nr_iowait);
         schedule();
@@ -4163,7 +4163,7 @@ EXPORT_SYMBOL(io_schedule);
 
 long __sched io_schedule_timeout(long timeout)
 {
-        struct runqueue *rq = &per_cpu(runqueues, raw_smp_processor_id());
+        struct runqueue *rq = &__raw_get_cpu_var(runqueues);
         long ret;
 
         atomic_inc(&rq->nr_iowait);