The updated patch below avoids dropping extraneous files into your source
tree.
Thanx, Paul
>Hello!
>
>Interpreting silence as assent... ;-)
>
>Here is a patch containing read_barrier_depends(), memory_barrier(),
>read_barrier(), and write_barrier(), as discussed on lkml a while back.
>(See http://www.uwsg.indiana.edu/hypermail/linux/kernel/0110.1/1430.html)
>
>This patch defines read_barrier_depends() as in the previous patch.
>In the name of backwards compatibility, it defines mb(), rmb(), and wmb()
>in terms of the new memory_barrier(), read_barrier(), and write_barrier()
>in each architecture. If this approach is acceptable, I will follow up
>with patches to change the existing uses of smp_mb(), smp_rmb(), smp_wmb(),
>mb(), rmb(), and wmb() to instead use the new names. Finally, I will
>produce patches to remove the definitions of the old names.
>
>Thoughts?
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-alpha/system.h linux-2.4.14.read_barrier/include/asm-alpha/system.h
--- linux-2.4.14/include/asm-alpha/system.h Thu Oct 4 18:47:08 2001
+++ linux-2.4.14.read_barrier/include/asm-alpha/system.h Tue Nov 6 16:46:52 2001
@@ -142,22 +142,31 @@
extern struct task_struct* alpha_switch_to(unsigned long, struct task_struct*);
-#define mb() \
+#define memory_barrier() \
__asm__ __volatile__("mb": : :"memory")
-#define rmb() \
+#define read_barrier() \
__asm__ __volatile__("mb": : :"memory")
-#define wmb() \
+#define read_barrier_depends() \
+__asm__ __volatile__("mb": : :"memory")
+
+#define write_barrier() \
__asm__ __volatile__("wmb": : :"memory")
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
+
#ifdef CONFIG_SMP
#define smp_mb() mb()
#define smp_rmb() rmb()
+#define smp_read_barrier_depends() read_barrier_depends()
#define smp_wmb() wmb()
#else
#define smp_mb() barrier()
#define smp_rmb() barrier()
+#define smp_read_barrier_depends() barrier()
#define smp_wmb() barrier()
#endif
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-arm/system.h linux-2.4.14.read_barrier/include/asm-arm/system.h
--- linux-2.4.14/include/asm-arm/system.h Mon Nov 27 17:07:59 2000
+++ linux-2.4.14.read_barrier/include/asm-arm/system.h Tue Nov 6 16:48:09 2001
@@ -36,11 +36,16 @@
*/
#include <asm/proc/system.h>
-#define mb() __asm__ __volatile__ ("" : : : "memory")
-#define rmb() mb()
-#define wmb() mb()
+#define memory_barrier() __asm__ __volatile__ ("" : : : "memory")
+#define read_barrier() mb()
+#define read_barrier_depends() do { } while(0)
+#define write_barrier() mb()
#define nop() __asm__ __volatile__("mov\tr0,r0\t@ nop\n\t");
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
+
#define prepare_to_switch() do { } while(0)
/*
@@ -67,12 +72,14 @@
#define smp_mb() mb()
#define smp_rmb() rmb()
+#define smp_read_barrier_depends() read_barrier_depends()
#define smp_wmb() wmb()
#else
#define smp_mb() barrier()
#define smp_rmb() barrier()
+#define smp_read_barrier_depends() do { } while(0)
#define smp_wmb() barrier()
#define cli() __cli()
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-cris/system.h linux-2.4.14.read_barrier/include/asm-cris/system.h
--- linux-2.4.14/include/asm-cris/system.h Mon Oct 8 11:43:54 2001
+++ linux-2.4.14.read_barrier/include/asm-cris/system.h Tue Nov 6 16:48:38 2001
@@ -147,17 +147,24 @@
#endif
}
-#define mb() __asm__ __volatile__ ("" : : : "memory")
-#define rmb() mb()
-#define wmb() mb()
+#define memory_barrier() __asm__ __volatile__ ("" : : : "memory")
+#define read_barrier() mb()
+#define read_barrier_depends() do { } while(0)
+#define write_barrier() mb()
+
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
#ifdef CONFIG_SMP
#define smp_mb() mb()
#define smp_rmb() rmb()
+#define smp_read_barrier_depends() read_barrier_depends()
#define smp_wmb() wmb()
#else
#define smp_mb() barrier()
#define smp_rmb() barrier()
+#define smp_read_barrier_depends() do { } while(0)
#define smp_wmb() barrier()
#endif
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-i386/system.h linux-2.4.14.read_barrier/include/asm-i386/system.h
--- linux-2.4.14/include/asm-i386/system.h Mon Nov 5 12:42:13 2001
+++ linux-2.4.14.read_barrier/include/asm-i386/system.h Tue Nov 6 16:49:45 2001
@@ -286,22 +286,32 @@
* nop for these.
*/
-#define mb() __asm__ __volatile__ ("lock; addl $0,0(%%esp)": : :"memory")
-#define rmb() mb()
+#define memory_barrier() \
+ __asm__ __volatile__ ("lock; addl $0,0(%%esp)": : :"memory")
+#define read_barrier() mb()
+#define read_barrier_depends() do { } while(0)
#ifdef CONFIG_X86_OOSTORE
-#define wmb() __asm__ __volatile__ ("lock; addl $0,0(%%esp)": : :"memory")
+#define write_barrier() \
+ __asm__ __volatile__ ("lock; addl $0,0(%%esp)": : :"memory")
#else
-#define wmb() __asm__ __volatile__ ("": : :"memory")
+#define write_barrier() \
+ __asm__ __volatile__ ("": : :"memory")
#endif
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
+
#ifdef CONFIG_SMP
#define smp_mb() mb()
#define smp_rmb() rmb()
+#define smp_read_barrier_depends() read_barrier_depends()
#define smp_wmb() wmb()
#else
#define smp_mb() barrier()
#define smp_rmb() barrier()
+#define smp_read_barrier_depends() do { } while(0)
#define smp_wmb() barrier()
#endif
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-ia64/system.h linux-2.4.14.read_barrier/include/asm-ia64/system.h
--- linux-2.4.14/include/asm-ia64/system.h Tue Jul 31 10:30:09 2001
+++ linux-2.4.14.read_barrier/include/asm-ia64/system.h Tue Nov 6 16:50:56 2001
@@ -80,33 +80,43 @@
* architecturally visible effects of a memory access have occurred
* (at a minimum, this means the memory has been read or written).
*
- * wmb(): Guarantees that all preceding stores to memory-
+ * write_barrier(): Guarantees that all preceding stores to memory-
* like regions are visible before any subsequent
* stores and that all following stores will be
* visible only after all previous stores.
- * rmb(): Like wmb(), but for reads.
- * mb(): wmb()/rmb() combo, i.e., all previous memory
+ * read_barrier(): Like wmb(), but for reads.
+ * read_barrier_depends(): Like rmb(), but only for pairs
+ * of loads where the second load depends on the
+ * value loaded by the first.
+ * memory_barrier(): wmb()/rmb() combo, i.e., all previous memory
* accesses are visible before all subsequent
* accesses and vice versa. This is also known as
* a "fence."
*
- * Note: "mb()" and its variants cannot be used as a fence to order
- * accesses to memory mapped I/O registers. For that, mf.a needs to
+ * Note: "memory_barrier()" and its variants cannot be used as a fence to
+ * order accesses to memory mapped I/O registers. For that, mf.a needs to
* be used. However, we don't want to always use mf.a because (a)
* it's (presumably) much slower than mf and (b) mf.a is supported for
* sequential memory pages only.
*/
-#define mb() __asm__ __volatile__ ("mf" ::: "memory")
-#define rmb() mb()
-#define wmb() mb()
+#define memory_barrier() __asm__ __volatile__ ("mf" ::: "memory")
+#define read_barrier() mb()
+#define read_barrier_depends() do { } while(0)
+#define write_barrier() mb()
+
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
#ifdef CONFIG_SMP
# define smp_mb() mb()
# define smp_rmb() rmb()
+# define smp_read_barrier_depends() read_barrier_depends()
# define smp_wmb() wmb()
#else
# define smp_mb() barrier()
# define smp_rmb() barrier()
+# define smp_read_barrier_depends() do { } while(0)
# define smp_wmb() barrier()
#endif
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-m68k/system.h linux-2.4.14.read_barrier/include/asm-m68k/system.h
--- linux-2.4.14/include/asm-m68k/system.h Thu Oct 25 13:53:55 2001
+++ linux-2.4.14.read_barrier/include/asm-m68k/system.h Tue Nov 6 16:51:50 2001
@@ -78,14 +78,20 @@
* Not really required on m68k...
*/
#define nop() do { asm volatile ("nop"); barrier(); } while (0)
-#define mb() barrier()
-#define rmb() barrier()
-#define wmb() barrier()
+#define memory_barrier() barrier()
+#define read_barrier() barrier()
+#define read_barrier_depends() do { } while(0)
+#define write_barrier() barrier()
#define set_mb(var, value) do { xchg(&var, value); } while (0)
#define set_wmb(var, value) do { var = value; wmb(); } while (0)
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
+
#define smp_mb() barrier()
#define smp_rmb() barrier()
+#define smp_read_barrier_depends() do { } while(0)
#define smp_wmb() barrier()
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-mips/system.h linux-2.4.14.read_barrier/include/asm-mips/system.h
--- linux-2.4.14/include/asm-mips/system.h Sun Sep 9 10:43:01 2001
+++ linux-2.4.14.read_barrier/include/asm-mips/system.h Tue Nov 6 16:53:02 2001
@@ -149,13 +149,14 @@
#ifdef CONFIG_CPU_HAS_WB
#include <asm/wbflush.h>
-#define rmb() do { } while(0)
-#define wmb() wbflush()
-#define mb() wbflush()
+#define read_barrier() do { } while(0)
+#define read_barrier_depends() do { } while(0)
+#define write_barrier() wbflush()
+#define memory_barrier() wbflush()
#else /* CONFIG_CPU_HAS_WB */
-#define mb() \
+#define memory_barrier() \
__asm__ __volatile__( \
"# prevent instructions being moved around\n\t" \
".set\tnoreorder\n\t" \
@@ -165,18 +166,25 @@
: /* no output */ \
: /* no input */ \
: "memory")
-#define rmb() mb()
-#define wmb() mb()
+#define read_barrier() mb()
+#define read_barrier_depends() do { } while(0)
+#define write_barrier() mb()
#endif /* CONFIG_CPU_HAS_WB */
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
+
#ifdef CONFIG_SMP
#define smp_mb() mb()
#define smp_rmb() rmb()
+#define smp_read_barrier_depends() read_barrier_depends()
#define smp_wmb() wmb()
#else
#define smp_mb() barrier()
#define smp_rmb() barrier()
+#define smp_read_barrier_depends() do { } while(0)
#define smp_wmb() barrier()
#endif
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-mips64/system.h linux-2.4.14.read_barrier/include/asm-mips64/system.h
--- linux-2.4.14/include/asm-mips64/system.h Wed Jul 4 11:50:39 2001
+++ linux-2.4.14.read_barrier/include/asm-mips64/system.h Tue Nov 6 16:53:35 2001
@@ -137,7 +137,7 @@
/*
* These are probably defined overly paranoid ...
*/
-#define mb() \
+#define memory_barrier() \
__asm__ __volatile__( \
"# prevent instructions being moved around\n\t" \
".set\tnoreorder\n\t" \
@@ -146,16 +146,23 @@
: /* no output */ \
: /* no input */ \
: "memory")
-#define rmb() mb()
-#define wmb() mb()
+#define read_barrier() mb()
+#define read_barrier_depends() do { } while(0)
+#define write_barrier() mb()
+
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
#ifdef CONFIG_SMP
#define smp_mb() mb()
#define smp_rmb() rmb()
+#define smp_read_barrier_depends() read_barrier_depends()
#define smp_wmb() wmb()
#else
#define smp_mb() barrier()
#define smp_rmb() barrier()
+#define smp_read_barrier_depends() do { } while(0)
#define smp_wmb() barrier()
#endif
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-parisc/system.h linux-2.4.14.read_barrier/include/asm-parisc/system.h
--- linux-2.4.14/include/asm-parisc/system.h Wed Dec 6 11:46:39 2000
+++ linux-2.4.14.read_barrier/include/asm-parisc/system.h Tue Nov 6 16:54:55 2001
@@ -50,6 +50,7 @@
#ifdef CONFIG_SMP
#define smp_mb() mb()
#define smp_rmb() rmb()
+#define smp_read_barrier_depends() do { } while(0)
#define smp_wmb() wmb()
#else
/* This is simply the barrier() macro from linux/kernel.h but when serial.c
@@ -58,6 +59,7 @@
*/
#define smp_mb() __asm__ __volatile__("":::"memory");
#define smp_rmb() __asm__ __volatile__("":::"memory");
+#define smp_read_barrier_depends() do { } while(0)
#define smp_wmb() __asm__ __volatile__("":::"memory");
#endif
@@ -120,8 +122,14 @@
: "r" (gr), "i" (cr))
-#define mb() __asm__ __volatile__ ("sync" : : :"memory")
-#define wmb() mb()
+#define memory_barrier() __asm__ __volatile__ ("sync" : : :"memory")
+#define read_barrier() mb()
+#define write_barrier() mb()
+#define read_barrier_depends() do { } while(0)
+
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
extern unsigned long __xchg(unsigned long, unsigned long *, int);
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-ppc/system.h linux-2.4.14.read_barrier/include/asm-ppc/system.h
--- linux-2.4.14/include/asm-ppc/system.h Tue Aug 28 06:58:33 2001
+++ linux-2.4.14.read_barrier/include/asm-ppc/system.h Tue Nov 6 16:55:47 2001
@@ -22,17 +22,24 @@
* providing an ordering (separately) for (a) cacheable stores and (b)
* loads and stores to non-cacheable memory (e.g. I/O devices).
*
- * mb() prevents loads and stores being reordered across this point.
- * rmb() prevents loads being reordered across this point.
- * wmb() prevents stores being reordered across this point.
+ * memory_barrier() prevents loads and stores being reordered across this point.
+ * read_barrier() prevents loads being reordered across this point.
+ * read_barrier_depends() prevents data-dependant loads being reordered
+ * across this point (nop on PPC).
+ * write_barrier() prevents stores being reordered across this point.
*
* We can use the eieio instruction for wmb, but since it doesn't
* give any ordering guarantees about loads, we have to use the
* stronger but slower sync instruction for mb and rmb.
*/
-#define mb() __asm__ __volatile__ ("sync" : : : "memory")
-#define rmb() __asm__ __volatile__ ("sync" : : : "memory")
-#define wmb() __asm__ __volatile__ ("eieio" : : : "memory")
+#define memory_barrier() __asm__ __volatile__ ("sync" : : : "memory")
+#define read_barrier() __asm__ __volatile__ ("sync" : : : "memory")
+#define read_barrier_depends() do { } while(0)
+#define write_barrier() __asm__ __volatile__ ("eieio" : : : "memory")
+
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
#define set_mb(var, value) do { var = value; mb(); } while (0)
#define set_wmb(var, value) do { var = value; wmb(); } while (0)
@@ -40,10 +47,12 @@
#ifdef CONFIG_SMP
#define smp_mb() mb()
#define smp_rmb() rmb()
+#define smp_read_barrier_depends() read_barrier_depends()
#define smp_wmb() wmb()
#else
#define smp_mb() __asm__ __volatile__("": : :"memory")
#define smp_rmb() __asm__ __volatile__("": : :"memory")
+#define smp_read_barrier_depends() do { } while(0)
#define smp_wmb() __asm__ __volatile__("": : :"memory")
#endif /* CONFIG_SMP */
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-s390/system.h linux-2.4.14.read_barrier/include/asm-s390/system.h
--- linux-2.4.14/include/asm-s390/system.h Wed Jul 25 14:12:02 2001
+++ linux-2.4.14.read_barrier/include/asm-s390/system.h Tue Nov 6 16:56:13 2001
@@ -115,14 +115,20 @@
#define eieio() __asm__ __volatile__ ("BCR 15,0")
# define SYNC_OTHER_CORES(x) eieio()
-#define mb() eieio()
-#define rmb() eieio()
-#define wmb() eieio()
+#define memory_barrier() eieio()
+#define read_barrier() eieio()
+#define read_barrier_depends() do { } while(0)
+#define write_barrier() eieio()
#define smp_mb() mb()
#define smp_rmb() rmb()
+#define smp_read_barrier_depends() read_barrier_depends()
#define smp_wmb() wmb()
#define smp_mb__before_clear_bit() smp_mb()
#define smp_mb__after_clear_bit() smp_mb()
+
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
#define set_mb(var, value) do { var = value; mb(); } while (0)
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-s390x/system.h linux-2.4.14.read_barrier/include/asm-s390x/system.h
--- linux-2.4.14/include/asm-s390x/system.h Wed Jul 25 14:12:03 2001
+++ linux-2.4.14.read_barrier/include/asm-s390x/system.h Tue Nov 6 16:56:44 2001
@@ -128,17 +128,23 @@
#define eieio() __asm__ __volatile__ ("BCR 15,0")
# define SYNC_OTHER_CORES(x) eieio()
-#define mb() eieio()
-#define rmb() eieio()
-#define wmb() eieio()
+#define memory_barrier() eieio()
+#define read_barrier() eieio()
+#define read_barrier_depends() do { } while(0)
+#define write_barrier() eieio()
#define smp_mb() mb()
#define smp_rmb() rmb()
+#define smp_read_barrier_depends() read_barrier_depends()
#define smp_wmb() wmb()
#define smp_mb__before_clear_bit() smp_mb()
#define smp_mb__after_clear_bit() smp_mb()
#define set_mb(var, value) do { var = value; mb(); } while (0)
#define set_wmb(var, value) do { var = value; wmb(); } while (0)
+
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
/* interrupt control.. */
#define __sti() ({ \
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-sh/system.h linux-2.4.14.read_barrier/include/asm-sh/system.h
--- linux-2.4.14/include/asm-sh/system.h Sat Sep 8 12:29:09 2001
+++ linux-2.4.14.read_barrier/include/asm-sh/system.h Tue Nov 6 16:57:42 2001
@@ -86,17 +86,24 @@
extern void __xchg_called_with_bad_pointer(void);
-#define mb() __asm__ __volatile__ ("": : :"memory")
-#define rmb() mb()
-#define wmb() __asm__ __volatile__ ("": : :"memory")
+#define memory_barrier() __asm__ __volatile__ ("": : :"memory")
+#define read_barrier() mb()
+#define read_barrier_depends() do { } while(0)
+#define write_barrier() __asm__ __volatile__ ("": : :"memory")
+
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
#ifdef CONFIG_SMP
#define smp_mb() mb()
#define smp_rmb() rmb()
+#define smp_read_barrier_depends() read_barrier_depends()
#define smp_wmb() wmb()
#else
#define smp_mb() barrier()
#define smp_rmb() barrier()
+#define smp_read_barrier_depends() do { } while(0)
#define smp_wmb() barrier()
#endif
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-sparc/system.h linux-2.4.14.read_barrier/include/asm-sparc/system.h
--- linux-2.4.14/include/asm-sparc/system.h Tue Oct 30 15:08:11 2001
+++ linux-2.4.14.read_barrier/include/asm-sparc/system.h Tue Nov 6 16:58:11 2001
@@ -275,14 +275,20 @@
#endif
/* XXX Change this if we ever use a PSO mode kernel. */
-#define mb() __asm__ __volatile__ ("" : : : "memory")
-#define rmb() mb()
-#define wmb() mb()
+#define memory_barrier() __asm__ __volatile__ ("" : : : "memory")
+#define read_barrier() mb()
+#define read_barrier_depends() do { } while(0)
+#define write_barrier() mb()
#define set_mb(__var, __value) do { __var = __value; mb(); } while(0)
#define set_wmb(__var, __value) set_mb(__var, __value)
#define smp_mb() __asm__ __volatile__("":::"memory");
#define smp_rmb() __asm__ __volatile__("":::"memory");
+#define smp_read_barrier_depends() do { } while(0)
#define smp_wmb() __asm__ __volatile__("":::"memory");
+
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
#define nop() __asm__ __volatile__ ("nop");
diff -urN -X /home/mckenney/dontdiff linux-2.4.14/include/asm-sparc64/system.h linux-2.4.14.read_barrier/include/asm-sparc64/system.h
--- linux-2.4.14/include/asm-sparc64/system.h Fri Sep 7 11:01:20 2001
+++ linux-2.4.14.read_barrier/include/asm-sparc64/system.h Tue Nov 6 16:59:02 2001
@@ -96,22 +96,29 @@
#define nop() __asm__ __volatile__ ("nop")
#define membar(type) __asm__ __volatile__ ("membar " type : : : "memory");
-#define mb() \
+#define memory_barrier() \
membar("#LoadLoad | #LoadStore | #StoreStore | #StoreLoad");
-#define rmb() membar("#LoadLoad")
-#define wmb() membar("#StoreStore")
+#define read_barrier() membar("#LoadLoad")
+#define read_barrier_depends() do { } while(0)
+#define write_barrier() membar("#StoreStore")
#define set_mb(__var, __value) \
do { __var = __value; membar("#StoreLoad | #StoreStore"); } while(0)
#define set_wmb(__var, __value) \
do { __var = __value; membar("#StoreStore"); } while(0)
+#define mb() memory_barrier()
+#define rmb() read_barrier()
+#define wmb() write_barrier()
+
#ifdef CONFIG_SMP
#define smp_mb() mb()
#define smp_rmb() rmb()
+#define smp_read_barrier_depends() read_barrier_depends()
#define smp_wmb() wmb()
#else
#define smp_mb() __asm__ __volatile__("":::"memory");
#define smp_rmb() __asm__ __volatile__("":::"memory");
+#define smp_read_barrier_depends() do { } while(0)
#define smp_wmb() __asm__ __volatile__("":::"memory");
#endif
-
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