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, 4 deletions

diff --git a/arch/x86/um/asm/barrier.h b/arch/x86/um/asm/barrier.h
index cc04e67bfd05..d6511d954e2b 100644
--- a/arch/x86/um/asm/barrier.h
+++ b/arch/x86/um/asm/barrier.h
@@ -29,8 +29,6 @@
 
 #endif /* CONFIG_X86_32 */
 
-#define read_barrier_depends()  do { } while (0)
-
 #ifdef CONFIG_SMP
 
 #define smp_mb()        mb()
@@ -42,7 +40,6 @@
 
 #define smp_wmb()       barrier()
 
-#define smp_read_barrier_depends()      read_barrier_depends()
 #define set_mb(var, value) do { (void)xchg(&var, value); } while (0)
 
 #else /* CONFIG_SMP */
@@ -50,11 +47,13 @@
 #define smp_mb()        barrier()
 #define smp_rmb()       barrier()
 #define smp_wmb()       barrier()
-#define smp_read_barrier_depends()      do { } while (0)
 #define set_mb(var, value) do { var = value; barrier(); } while (0)
 
 #endif /* CONFIG_SMP */
 
+#define read_barrier_depends()          do { } while (0)
+#define smp_read_barrier_depends()      do { } while (0)
+
 /*
  * Stop RDTSC speculation. This is needed when you need to use RDTSC
  * (or get_cycles or vread that possibly accesses the TSC) in a defined