local_t: i386 extension

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 178 insertions, 27 deletions

diff --git a/include/asm-i386/local.h b/include/asm-i386/local.h
index 12060e22f7e2..e13d3e98823f 100644
--- 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) \
+        (cmpxchg_local(&((l)->a.counter), (o), (n)))
+/* Always has a lock prefix */
+#define local_xchg(l, n) (xchg(&((l)->a.counter), (n)))
+
+/**
+ * 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 */