arch: Cleanup read_barrier_depends() and comments

This patch is meant to cleanup the handling of read_barrier_depends and
smp_read_barrier_depends.  In multiple spots in the kernel headers
read_barrier_depends is defined as "do {} while (0)", however we then go
into the SMP vs non-SMP sections and have the SMP version reference
read_barrier_depends, and the non-SMP define it as yet another empty
do/while.

With this commit I went through and cleaned out the duplicate definitions
and reduced the number of definitions down to 2 per header.  In addition I
moved the 50 line comments for the macro from the x86 and mips headers that
defined it as an empty do/while to those that were actually defining the
macro, alpha and blackfin.

Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/s390/include/asm/barrier.h b/arch/s390/include/asm/barrier.h
index b5dce6544d76..33d191d295e4 100644
--- a/arch/s390/include/asm/barrier.h
+++ b/arch/s390/include/asm/barrier.h
@@ -24,11 +24,12 @@
 
 #define rmb()                           mb()
 #define wmb()                           mb()
-#define read_barrier_depends()          do { } while(0)
 #define smp_mb()                        mb()
 #define smp_rmb()                       rmb()
 #define smp_wmb()                       wmb()
-#define smp_read_barrier_depends()      read_barrier_depends()
+
+#define read_barrier_depends()          do { } while (0)
+#define smp_read_barrier_depends()      do { } while (0)
 
 #define smp_mb__before_atomic()         smp_mb()
 #define smp_mb__after_atomic()          smp_mb()