From: Zwane Mwaikambo <zwane@linuxpower.ca>
This is a follow up to the previous patches for ia64 and i386, it will
allow x86_64 to reenable interrupts during contested locks depending on
previous interrupt enable status. It has been runtime and compile tested
on UP and 2x SMP Linux-tiny/x86_64.
Signed-off-by: Zwane Mwaikambo <zwane@fsmlabs.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/include/asm-x86_64/spinlock.h | 32 +++++++++++++++++++++++++++++++-
1 files changed, 31 insertions(+), 1 deletion(-)
diff -puN include/asm-x86_64/spinlock.h~allow-x86_64-to-reenable-interrupts-on-contention include/asm-x86_64/spinlock.h
--- 25/include/asm-x86_64/spinlock.h~allow-x86_64-to-reenable-interrupts-on-contention 2004-09-21 01:53:39.131974400 -0700
+++ 25-akpm/include/asm-x86_64/spinlock.h 2004-09-21 01:53:39.134973944 -0700
@@ -44,7 +44,6 @@ typedef struct {
#define spin_is_locked(x) (*(volatile signed char *)(&(x)->lock) <= 0)
#define spin_unlock_wait(x) do { barrier(); } while(spin_is_locked(x))
-#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
#define spin_lock_string \
"\n1:\t" \
@@ -58,6 +57,23 @@ typedef struct {
"jmp 1b\n" \
LOCK_SECTION_END
+#define spin_lock_string_flags \
+ "\n1:\t" \
+ "lock ; decb %0\n\t" \
+ "js 2f\n\t" \
+ LOCK_SECTION_START("") \
+ "2:\t" \
+ "test $0x200, %1\n\t" \
+ "jz 3f\n\t" \
+ "sti\n\t" \
+ "3:\t" \
+ "rep;nop\n\t" \
+ "cmpb $0, %0\n\t" \
+ "jle 3b\n\t" \
+ "cli\n\t" \
+ "jmp 1b\n" \
+ LOCK_SECTION_END
+
/*
* This works. Despite all the confusion.
* (except on PPro SMP or if we are using OOSTORE)
@@ -126,6 +142,20 @@ static inline void _raw_spin_lock(spinlo
:"=m" (lock->lock) : : "memory");
}
+static inline void _raw_spin_lock_flags (spinlock_t *lock, unsigned long flags)
+{
+#ifdef CONFIG_DEBUG_SPINLOCK
+ __label__ here;
+here:
+ if (unlikely(lock->magic != SPINLOCK_MAGIC)) {
+ printk("eip: %p\n", &&here);
+ BUG();
+ }
+#endif
+ __asm__ __volatile__(spin_lock_string_flags
+ :"=m" (lock->lock) : "r" (flags) : "memory");
+}
+
/*
* Read-write spinlocks, allowing multiple readers
_