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SubjectRe: [PATCH][2.6-mm] Allow i386 to reenable interrupts on lock contention
On Sat, 1 May 2004, Andrew Morton wrote:

> Could we move all the irq-handling stuff into the out-of-line section, to
> keep the fast-path cache footprint smaller?

Of course, oversight on my part. Done and restested.

Index: linux-2.6.6-rc3-mm1/include/asm-i386/spinlock.h
===================================================================
RCS file: /home/cvsroot/linux-2.6.6-rc3-mm1/include/asm-i386/spinlock.h,v
retrieving revision 1.1.1.1
diff -u -p -B -r1.1.1.1 spinlock.h
--- linux-2.6.6-rc3-mm1/include/asm-i386/spinlock.h 1 May 2004 08:19:15 -0000 1.1.1.1
+++ linux-2.6.6-rc3-mm1/include/asm-i386/spinlock.h 1 May 2004 21:53:36 -0000
@@ -42,7 +42,6 @@ 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)

#ifdef CONFIG_SPINLINE

@@ -58,6 +57,21 @@ typedef struct {
"jmp 1b\n" \
"3:\t"

+ #define spin_lock_string_flags \
+ "\n1:\t" \
+ "lock ; decb %0\n\t" \
+ "jns 3f\n" \
+ "testl $0x200, %1\n\t" \
+ "jz 2f\n\t" \
+ "sti\n\t" \
+ "2:\t" \
+ "rep;nop\n\t" \
+ "cmpb $0, %0\n\t" \
+ "jle 2b\n\t" \
+ "cli\n\t" \
+ "jmp 1b\n" \
+ "3:\t"
+
#else /* !CONFIG_SPINLINE */

#define spin_lock_string \
@@ -72,6 +86,23 @@ 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" \
+ "testl $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
+
#endif /* CONFIG_SPINLINE */
/*
* This works. Despite all the confusion.
@@ -143,6 +174,20 @@ here:
:"=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
-
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