[patch 02/12] uml: cpu_relax fix

[blaisorblade]

Use rep_nop instead of barrier for cpu_relax, following $(SUBARCH)'s doing
that (i.e. i386 and x86_64).

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@xxxxxxxx>
---

 linux-2.6.11-paolo/include/asm-um/processor-generic.h |    2 --
 linux-2.6.11-paolo/include/asm-um/processor-i386.h    |    8 ++++++++
 linux-2.6.11-paolo/include/asm-um/processor-x86_64.h  |    8 ++++++++
 3 files changed, 16 insertions(+), 2 deletions(-)

diff -puN include/asm-um/processor-generic.h~uml-cpu_relax include/asm-um/processor-generic.h
--- linux-2.6.11/include/asm-um/processor-generic.h~uml-cpu_relax	2005-03-22 16:52:25.000000000 +0100
+++ linux-2.6.11-paolo/include/asm-um/processor-generic.h	2005-03-22 16:54:41.000000000 +0100
@@ -16,8 +16,6 @@ struct task_struct;
 
 struct mm_struct;
 
-#define cpu_relax()   barrier()
-
 struct thread_struct {
 	int forking;
 	int nsyscalls;
diff -puN include/asm-um/processor-i386.h~uml-cpu_relax include/asm-um/processor-i386.h
--- linux-2.6.11/include/asm-um/processor-i386.h~uml-cpu_relax	2005-03-22 16:53:43.000000000 +0100
+++ linux-2.6.11-paolo/include/asm-um/processor-i386.h	2005-03-22 16:54:39.000000000 +0100
@@ -19,6 +19,14 @@ struct arch_thread {
 
 #include "asm/arch/user.h"
 
+/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
+static inline void rep_nop(void)
+{
+	__asm__ __volatile__("rep;nop": : :"memory");
+}
+
+#define cpu_relax()	rep_nop()
+
 /*
  * Default implementation of macro that returns current
  * instruction pointer ("program counter"). Stolen
diff -puN include/asm-um/processor-x86_64.h~uml-cpu_relax include/asm-um/processor-x86_64.h
--- linux-2.6.11/include/asm-um/processor-x86_64.h~uml-cpu_relax	2005-03-22 16:56:30.000000000 +0100
+++ linux-2.6.11-paolo/include/asm-um/processor-x86_64.h	2005-03-22 16:56:32.000000000 +0100
@@ -12,6 +12,14 @@
 struct arch_thread {
 };
 
+/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
+extern inline void rep_nop(void)
+{
+	__asm__ __volatile__("rep;nop": : :"memory");
+}
+
+#define cpu_relax()   rep_nop()
+
 #define INIT_ARCH_THREAD { }
 
 #define current_text_addr() \
_
-
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