[PATCH 03/10] local_t : i386 extension

[Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>]

local_t : i386 extension

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

--- a/include/asm-i386/local.h
+++ b/include/asm-i386/local.h
@@ -2,47 +2,198 @@
 #define _ARCH_I386_LOCAL_H
 
 #include <linux/percpu.h>
+#include <asm/system.h>
+#include <asm/atomic.h>
 
 typedef struct
 {
-	volatile long counter;
+	atomic_long_t a;
 } local_t;
 
-#define LOCAL_INIT(i)	{ (i) }
+#define LOCAL_INIT(i)	{ ATOMIC_LONG_INIT(i) }
 
-#define local_read(v)	((v)->counter)
-#define local_set(v,i)	(((v)->counter) = (i))
+#define local_read(l)	atomic_long_read(&(l)->a)
+#define local_set(l,i)	atomic_long_set(&(l)->a, (i))
 
-static __inline__ void local_inc(local_t *v)
+static __inline__ void local_inc(local_t *l)
 {
 	__asm__ __volatile__(
 		"incl %0"
-		:"+m" (v->counter));
+		:"+m" (l->a.counter));
 }
 
-static __inline__ void local_dec(local_t *v)
+static __inline__ void local_dec(local_t *l)
 {
 	__asm__ __volatile__(
 		"decl %0"
-		:"+m" (v->counter));
+		:"+m" (l->a.counter));
 }
 
-static __inline__ void local_add(long i, local_t *v)
+static __inline__ void local_add(long i, local_t *l)
 {
 	__asm__ __volatile__(
 		"addl %1,%0"
-		:"+m" (v->counter)
+		:"+m" (l->a.counter)
 		:"ir" (i));
 }
 
-static __inline__ void local_sub(long i, local_t *v)
+static __inline__ void local_sub(long i, local_t *l)
 {
 	__asm__ __volatile__(
 		"subl %1,%0"
-		:"+m" (v->counter)
+		:"+m" (l->a.counter)
 		:"ir" (i));
 }
 
+/**
+ * local_sub_and_test - subtract value from variable and test result
+ * @i: integer value to subtract
+ * @l: pointer of type local_t
+ * 
+ * Atomically subtracts @i from @l and returns
+ * true if the result is zero, or false for all
+ * other cases.
+ */
+static __inline__ int local_sub_and_test(long i, local_t *l)
+{
+	unsigned char c;
+
+	__asm__ __volatile__(
+		"subl %2,%0; sete %1"
+		:"+m" (l->a.counter), "=qm" (c)
+		:"ir" (i) : "memory");
+	return c;
+}
+
+/**
+ * local_dec_and_test - decrement and test
+ * @l: pointer of type local_t
+ * 
+ * Atomically decrements @l by 1 and
+ * returns true if the result is 0, or false for all other
+ * cases.
+ */ 
+static __inline__ int local_dec_and_test(local_t *l)
+{
+	unsigned char c;
+
+	__asm__ __volatile__(
+		"decl %0; sete %1"
+		:"+m" (l->a.counter), "=qm" (c)
+		: : "memory");
+	return c != 0;
+}
+
+/**
+ * local_inc_and_test - increment and test 
+ * @l: pointer of type local_t
+ * 
+ * Atomically increments @l by 1
+ * and returns true if the result is zero, or false for all
+ * other cases.
+ */ 
+static __inline__ int local_inc_and_test(local_t *l)
+{
+	unsigned char c;
+
+	__asm__ __volatile__(
+		"incl %0; sete %1"
+		:"+m" (l->a.counter), "=qm" (c)
+		: : "memory");
+	return c != 0;
+}
+
+/**
+ * local_add_negative - add and test if negative
+ * @l: pointer of type local_t
+ * @i: integer value to add
+ * 
+ * Atomically adds @i to @l and returns true
+ * if the result is negative, or false when
+ * result is greater than or equal to zero.
+ */ 
+static __inline__ int local_add_negative(long i, local_t *l)
+{
+	unsigned char c;
+
+	__asm__ __volatile__(
+		"addl %2,%0; sets %1"
+		:"+m" (l->a.counter), "=qm" (c)
+		:"ir" (i) : "memory");
+	return c;
+}
+
+/**
+ * local_add_return - add and return
+ * @l: pointer of type local_t
+ * @i: integer value to add
+ *
+ * Atomically adds @i to @l and returns @i + @l
+ */
+static __inline__ long local_add_return(long i, local_t *l)
+{
+	long __i;
+#ifdef CONFIG_M386
+	unsigned long flags;
+	if(unlikely(boot_cpu_data.x86==3))
+		goto no_xadd;
+#endif
+	/* Modern 486+ processor */
+	__i = i;
+	__asm__ __volatile__(
+		"xaddl %0, %1;"
+		:"+r" (i), "+m" (l->a.counter)
+		: : "memory");
+	return i + __i;
+
+#ifdef CONFIG_M386
+no_xadd: /* Legacy 386 processor */
+	local_irq_save(flags);
+	__i = local_read(l);
+	local_set(l, i + __i);
+	local_irq_restore(flags);
+	return i + __i;
+#endif
+}
+
+static __inline__ long local_sub_return(long i, local_t *l)
+{
+	return local_add_return(-i,l);
+}
+
+#define local_inc_return(l)  (local_add_return(1,l))
+#define local_dec_return(l)  (local_sub_return(1,l))
+
+#define local_cmpxchg(l, o, n) \
+	((long)cmpxchg_local(&((l)->a.counter), (o), (n)))
+/* Always has a lock prefix anyway */
+#define local_xchg(l, new) (xchg(&((l)->a.counter), new))
+
+/**
+ * local_add_unless - add unless the number is a given value
+ * @l: pointer of type local_t
+ * @a: the amount to add to l...
+ * @u: ...unless l is equal to u.
+ *
+ * Atomically adds @a to @l, so long as it was not @u.
+ * Returns non-zero if @l was not @u, and zero otherwise.
+ */
+#define local_add_unless(l, a, u)				\
+({								\
+	long c, old;						\
+	c = local_read(l);					\
+	for (;;) {						\
+		if (unlikely(c == (u)))				\
+			break;					\
+		old = local_cmpxchg((l), c, c + (a));	\
+		if (likely(old == c))				\
+			break;					\
+		c = old;					\
+	}							\
+	c != (u);						\
+})
+#define local_inc_not_zero(l) local_add_unless((l), 1, 0)
+
 /* On x86, these are no better than the atomic variants. */
 #define __local_inc(l)		local_inc(l)
 #define __local_dec(l)		local_dec(l)
@@ -56,27 +207,27 @@ static __inline__ void local_sub(long i, local_t *v)
 
 /* Need to disable preemption for the cpu local counters otherwise we could
    still access a variable of a previous CPU in a non atomic way. */
-#define cpu_local_wrap_v(v)	 	\
+#define cpu_local_wrap_v(l)	 	\
 	({ local_t res__;		\
 	   preempt_disable(); 		\
-	   res__ = (v);			\
+	   res__ = (l);			\
 	   preempt_enable();		\
 	   res__; })
-#define cpu_local_wrap(v)		\
+#define cpu_local_wrap(l)		\
 	({ preempt_disable();		\
-	   v;				\
+	   l;				\
 	   preempt_enable(); })		\
 
-#define cpu_local_read(v)    cpu_local_wrap_v(local_read(&__get_cpu_var(v)))
-#define cpu_local_set(v, i)  cpu_local_wrap(local_set(&__get_cpu_var(v), (i)))
-#define cpu_local_inc(v)     cpu_local_wrap(local_inc(&__get_cpu_var(v)))
-#define cpu_local_dec(v)     cpu_local_wrap(local_dec(&__get_cpu_var(v)))
-#define cpu_local_add(i, v)  cpu_local_wrap(local_add((i), &__get_cpu_var(v)))
-#define cpu_local_sub(i, v)  cpu_local_wrap(local_sub((i), &__get_cpu_var(v)))
-
-#define __cpu_local_inc(v)	cpu_local_inc(v)
-#define __cpu_local_dec(v)	cpu_local_dec(v)
-#define __cpu_local_add(i, v)	cpu_local_add((i), (v))
-#define __cpu_local_sub(i, v)	cpu_local_sub((i), (v))
+#define cpu_local_read(l)    cpu_local_wrap_v(local_read(&__get_cpu_var(l)))
+#define cpu_local_set(l, i)  cpu_local_wrap(local_set(&__get_cpu_var(l), (i)))
+#define cpu_local_inc(l)     cpu_local_wrap(local_inc(&__get_cpu_var(l)))
+#define cpu_local_dec(l)     cpu_local_wrap(local_dec(&__get_cpu_var(l)))
+#define cpu_local_add(i, l)  cpu_local_wrap(local_add((i), &__get_cpu_var(l)))
+#define cpu_local_sub(i, l)  cpu_local_wrap(local_sub((i), &__get_cpu_var(l)))
+
+#define __cpu_local_inc(l)	cpu_local_inc(l)
+#define __cpu_local_dec(l)	cpu_local_dec(l)
+#define __cpu_local_add(i, l)	cpu_local_add((i), (l))
+#define __cpu_local_sub(i, l)	cpu_local_sub((i), (l))
 
 #endif /* _ARCH_I386_LOCAL_H */
--- a/include/asm-i386/system.h
+++ b/include/asm-i386/system.h
@@ -274,6 +274,9 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz
 #define sync_cmpxchg(ptr,o,n)\
 	((__typeof__(*(ptr)))__sync_cmpxchg((ptr),(unsigned long)(o),\
 					(unsigned long)(n),sizeof(*(ptr))))
+#define cmpxchg_local(ptr,o,n)\
+	((__typeof__(*(ptr)))__cmpxchg_local((ptr),(unsigned long)(o),\
+					(unsigned long)(n),sizeof(*(ptr))))
 #endif
 
 static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
@@ -336,6 +339,33 @@ static inline unsigned long __sync_cmpxchg(volatile void *ptr,
 	return old;
 }
 
+static inline unsigned long __cmpxchg_local(volatile void *ptr,
+			unsigned long old, unsigned long new, int size)
+{
+	unsigned long prev;
+	switch (size) {
+	case 1:
+		__asm__ __volatile__("cmpxchgb %b1,%2"
+				     : "=a"(prev)
+				     : "q"(new), "m"(*__xg(ptr)), "0"(old)
+				     : "memory");
+		return prev;
+	case 2:
+		__asm__ __volatile__("cmpxchgw %w1,%2"
+				     : "=a"(prev)
+				     : "r"(new), "m"(*__xg(ptr)), "0"(old)
+				     : "memory");
+		return prev;
+	case 4:
+		__asm__ __volatile__("cmpxchgl %1,%2"
+				     : "=a"(prev)
+				     : "r"(new), "m"(*__xg(ptr)), "0"(old)
+				     : "memory");
+		return prev;
+	}
+	return old;
+}
+
 #ifndef CONFIG_X86_CMPXCHG
 /*
  * Building a kernel capable running on 80386. It may be necessary to
@@ -372,6 +402,17 @@ static inline unsigned long cmpxchg_386(volatile void *ptr, unsigned long old,
 					(unsigned long)(n), sizeof(*(ptr))); \
 	__ret;								\
 })
+#define cmpxchg_local(ptr,o,n)						\
+({									\
+	__typeof__(*(ptr)) __ret;					\
+	if (likely(boot_cpu_data.x86 > 3))				\
+		__ret = __cmpxchg_local((ptr), (unsigned long)(o),	\
+					(unsigned long)(n), sizeof(*(ptr))); \
+	else								\
+		__ret = cmpxchg_386((ptr), (unsigned long)(o),		\
+					(unsigned long)(n), sizeof(*(ptr))); \
+	__ret;								\
+})
 #endif
 
 #ifdef CONFIG_X86_CMPXCHG64
@@ -390,10 +431,26 @@ static inline unsigned long long __cmpxchg64(volatile void *ptr, unsigned long l
 	return prev;
 }
 
+static inline unsigned long long __cmpxchg64_local(volatile void *ptr,
+			unsigned long long old, unsigned long long new)
+{
+	unsigned long long prev;
+	__asm__ __volatile__("cmpxchg8b %3"
+			     : "=A"(prev)
+			     : "b"((unsigned long)new),
+			       "c"((unsigned long)(new >> 32)),
+			       "m"(*__xg(ptr)),
+			       "0"(old)
+			     : "memory");
+	return prev;
+}
+
 #define cmpxchg64(ptr,o,n)\
 	((__typeof__(*(ptr)))__cmpxchg64((ptr),(unsigned long long)(o),\
 					(unsigned long long)(n)))
-
+#define cmpxchg64_local(ptr,o,n)\
+	((__typeof__(*(ptr)))__cmpxchg64_local((ptr),(unsigned long long)(o),\
+					(unsigned long long)(n)))
 #endif
     
 /*