Re: ia64 atomic_dec_and_lock() patch

jerome.marchand
2003-12-11T09:58:22Z

[-- Attachment #1: Type: TEXT/PLAIN, Size: 2490 bytes --]

On Wed, 10 Dec 2003, David Mosberger wrote:

> Could you try replacing the inline-asm with cmpxchg() function? That
> way, you won't break compilation with Intel's compiler.

OK, here's the new patch.
I also join the right patch for lockmeter.

diff -urN linux-2.6.0-test11.orig/arch/ia64/Kconfig
linux-2.6.0-test11/arch/ia64/Kconfig
--- linux-2.6.0-test11.orig/arch/ia64/Kconfig 2003-12-09
11:26:58.000000000 +0100
+++ linux-2.6.0-test11/arch/ia64/Kconfig 2003-12-09
11:34:09.000000000 +0100
@@ -375,6 +375,11 @@
depends on IA32_SUPPORT
default y

+config HAVE_DEC_LOCK
+ bool
+ depends on (SMP || PREEMPT)
+ default y
+
config PERFMON
bool "Performance monitor support"
help
diff -urN linux-2.6.0-test11.orig/arch/ia64/lib/Makefile
linux-2.6.0-test11/arch/ia64/lib/Makefile
--- linux-2.6.0-test11.orig/arch/ia64/lib/Makefile 2003-12-09
11:26:58.000000000 +0100
+++ linux-2.6.0-test11/arch/ia64/lib/Makefile 2003-12-09
11:32:05.000000000 +0100
@@ -13,6 +13,7 @@
lib-$(CONFIG_MCKINLEY) += copy_page_mck.o memcpy_mck.o
lib-$(CONFIG_PERFMON) += carta_random.o
lib-$(CONFIG_MD_RAID5) += xor.o
+lib-$(CONFIG_HAVE_DEC_LOCK) += dec_and_lock.o

AFLAGS___divdi3.o =
AFLAGS___udivdi3.o = -DUNSIGNED
diff -urN linux-2.6.0-test11.orig/arch/ia64/lib/dec_and_lock.c
linux-2.6.0-test11/arch/ia64/lib/dec_and_lock.c
--- linux-2.6.0-test11.orig/arch/ia64/lib/dec_and_lock.c 1970-01-01
01:00:00.000000000 +0100
+++ linux-2.6.0-test11/arch/ia64/lib/dec_and_lock.c 2003-12-11
10:42:49.000000000 +0100
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2003 Jerome Marchand, Bull S.A.
+ *
+ * This file is released under the GPLv2, or at
+ * your option any later version.
+ *
+ * ia64 version of "atomic_dec_and_lock()" using
+ * the atomic "cmpxchg" instruction.
+ * This code is an adaptation of the x86 version
+ * of "atomic_dec_and_lock()".
+ */
+
+#include <linux/spinlock.h>
+#include <asm/atomic.h>
+
+int atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
+{
+ int counter;
+ int newcount;
+
+repeat:
+ counter = atomic_read(atomic);
+ newcount = counter-1;
+
+ if (!newcount)
+ goto slow_path;
+
+ if(cmpxchg(&atomic->counter, counter, newcount) != counter)
+ goto repeat;
+ return 0;
+
+slow_path:
+ spin_lock(lock);
+ if (atomic_dec_and_test(atomic))
+ return 1;
+ spin_unlock(lock);
+ return 0;
+}

[-- Attachment #2: lockmeter ia64 patch --]
[-- Type: TEXT/PLAIN, Size: 1914 bytes --]

diff -urN linux-2.6.0-test11.lockmeter.orig/arch/ia64/lib/dec_and_lock.c linux-2.6.0-test11.lockmeter/arch/ia64/lib/dec_and_lock.c
--- linux-2.6.0-test11.lockmeter.orig/arch/ia64/lib/dec_and_lock.c 2003-12-11 10:44:10.000000000 +0100
+++ linux-2.6.0-test11.lockmeter/arch/ia64/lib/dec_and_lock.c 2003-12-11 10:43:47.000000000 +0100
@@ -13,6 +13,7 @@
#include <linux/spinlock.h>
#include <asm/atomic.h>

+#ifndef ATOMIC_DEC_AND_LOCK
int atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
{
int counter;
@@ -36,3 +37,4 @@
spin_unlock(lock);
return 0;
}
+#endif
diff -urN linux-2.6.0-test11.lockmeter.orig/include/asm-ia64/spinlock.h linux-2.6.0-test11.lockmeter/include/asm-ia64/spinlock.h
--- linux-2.6.0-test11.lockmeter.orig/include/asm-ia64/spinlock.h 2003-12-11 10:09:42.000000000 +0100
+++ linux-2.6.0-test11.lockmeter/include/asm-ia64/spinlock.h 2003-12-11 10:15:45.000000000 +0100
@@ -247,13 +247,27 @@
extern void _metered_spin_unlock(spinlock_t *lock);

/*
- * Use a less efficient, and inline, atomic_dec_and_lock() if lockmetering
- * so we can see the callerPC of who is actually doing the spin_lock().
- * Otherwise, all we see is the generic rollup of all locks done by
- * atomic_dec_and_lock().
+ * Matches what is in arch/ia64/lib/dec_and_lock.c, except this one is
+ * "static inline" so that the spin_lock(), if actually invoked, is charged
+ * against the real caller, not against the catch-all atomic_dec_and_lock
*/
static inline int atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
{
+ int counter;
+ int newcount;
+
+repeat:
+ counter = atomic_read(atomic);
+ newcount = counter-1;
+
+ if (!newcount)
+ goto slow_path;
+
+ if(cmpxchg(&atomic->counter, counter, newcount) != counter)
+ goto repeat;
+ return 0;
+
+slow_path:
_metered_spin_lock(lock);
if (atomic_dec_and_test(atomic))
return 1;