* Christoph Hellwig ([email protected]) wrote:
> We already have local_t in asm/local.h for this purposed. Unfortunately
> several architecture implementations are rather suboptimal, but I'm sure
> the architecture maintainers would be interested in patches to optimize
> the various implementations.
>
Hi Christoph,
Here are the local.h modifications for i386, x86_64, powerpc, mips and arm (and
asm-generic). It adds support for various per-cpu atomic operations. It applies
on 2.6.18.
Mathieu
---BEGIN--
--- a/include/asm-i386/atomic.h
+++ b/include/asm-i386/atomic.h
@@ -207,8 +207,9 @@ static __inline__ int atomic_sub_return(
return atomic_add_return(-i,v);
}
-#define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
-#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
+#define atomic_cmpxchg(v, old, new) \
+ ((__typeof__((v)->counter))cmpxchg(&((v)->counter), (old), (new)))
+#define atomic_xchg(v, new) (xchg(&((v)->counter), (new)))
/**
* atomic_add_unless - add unless the number is a given value
@@ -221,7 +222,7 @@ #define atomic_xchg(v, new) (xchg(&((v)-
*/
#define atomic_add_unless(v, a, u) \
({ \
- int c, old; \
+ __typeof__((v)->counter) c, old; \
c = atomic_read(v); \
for (;;) { \
if (unlikely(c == (u))) \
--- a/include/asm-x86_64/local.h
+++ b/include/asm-x86_64/local.h
@@ -45,6 +45,139 @@ static inline void local_sub(long i, loc
:"ir" (i), "m" (v->counter));
}
+/**
+ * local_sub_and_test - subtract value from variable and test result
+ * @i: integer value to subtract
+ * @v: pointer to type local_t
+ *
+ * Atomically subtracts @i from @v 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 *v)
+{
+ unsigned char c;
+
+ __asm__ __volatile__(
+ "subq %2,%0; sete %1"
+ :"=m" (v->counter), "=qm" (c)
+ :"ir" (i), "m" (v->counter) : "memory");
+ return c;
+}
+
+/**
+ * local_dec_and_test - decrement and test
+ * @v: pointer to type local_t
+ *
+ * Atomically decrements @v 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 *v)
+{
+ unsigned char c;
+
+ __asm__ __volatile__(
+ "decq %0; sete %1"
+ :"=m" (v->counter), "=qm" (c)
+ :"m" (v->counter) : "memory");
+ return c != 0;
+}
+
+/**
+ * local_inc_and_test - increment and test
+ * @v: pointer to type local_t
+ *
+ * Atomically increments @v 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 *v)
+{
+ unsigned char c;
+
+ __asm__ __volatile__(
+ "incq %0; sete %1"
+ :"=m" (v->counter), "=qm" (c)
+ :"m" (v->counter) : "memory");
+ return c != 0;
+}
+
+/**
+ * local_add_negative - add and test if negative
+ * @i: integer value to add
+ * @v: pointer to type local_t
+ *
+ * Atomically adds @i to @v 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 *v)
+{
+ unsigned char c;
+
+ __asm__ __volatile__(
+ "addq %2,%0; sets %1"
+ :"=m" (v->counter), "=qm" (c)
+ :"ir" (i), "m" (v->counter) : "memory");
+ return c;
+}
+
+/**
+ * local_add_return - add and return
+ * @i: integer value to add
+ * @v: pointer to type local_t
+ *
+ * Atomically adds @i to @v and returns @i + @v
+ */
+static __inline__ long local_add_return(long i, local_t *v)
+{
+ long __i = i;
+ __asm__ __volatile__(
+ "xaddq %0, %1;"
+ :"=r"(i)
+ :"m"(v->counter), "0"(i));
+ return i + __i;
+}
+
+static __inline__ long local_sub_return(long i, local_t *v)
+{
+ return local_add_return(-i,v);
+}
+
+#define local_inc_return(v) (local_add_return(1,v))
+#define local_dec_return(v) (local_sub_return(1,v))
+
+#define local_cmpxchg(v, old, new) \
+ ((__typeof__((v)->counter))cmpxchg_local(&((v)->counter), (old), (new)))
+/* Always has a lock prefix anyway */
+#define local_xchg(v, new) (xchg(&((v)->counter), new))
+
+/**
+ * atomic_up_add_unless - add unless the number is a given value
+ * @v: pointer of type atomic_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns non-zero if @v was not @u, and zero otherwise.
+ */
+#define local_add_unless(v, a, u) \
+({ \
+ __typeof__((v)->counter) c, old; \
+ c = local_read(v); \
+ for (;;) { \
+ if (unlikely(c == (u))) \
+ break; \
+ old = local_cmpxchg((v), c, c + (a)); \
+ if (likely(old == c)) \
+ break; \
+ c = old; \
+ } \
+ c != (u); \
+})
+#define local_inc_not_zero(v) local_add_unless((v), 1, 0)
+
/* On x86-64 these are better than the atomic variants on SMP kernels
because they dont use a lock prefix. */
#define __local_inc(l) local_inc(l)
@@ -85,4 +218,4 @@ #define __cpu_local_dec(v) cpu_local_dec
#define __cpu_local_add(i, v) cpu_local_add((i), (v))
#define __cpu_local_sub(i, v) cpu_local_sub((i), (v))
-#endif /* _ARCH_I386_LOCAL_H */
+#endif /* _ARCH_X8664_LOCAL_H */
--- a/include/asm-powerpc/local.h
+++ b/include/asm-powerpc/local.h
@@ -1 +1,340 @@
-#include <asm-generic/local.h>
+#ifndef _ARCH_POWERPC_LOCAL_H
+#define _ARCH_POWERPC_LOCAL_H
+
+#include <linux/percpu.h>
+#include <asm/atomic.h>
+
+typedef struct
+{
+ volatile long counter;
+} local_t;
+
+#define LOCAL_INIT(i) { (i) }
+
+#define local_read(v) ((v)->counter)
+#define local_set(v,i) (((v)->counter) = (i))
+
+#define local_add(i,l) atomic_long_add((i),(&(l)->a))
+#define local_sub(i,l) atomic_long_sub((i),(&(l)->a))
+#define local_inc(l) atomic_long_inc(&(l)->a)
+#define local_dec(l) atomic_long_dec(&(l)->a)
+
+#ifndef __powerpc64__
+
+static __inline__ int local_add_return(int a, local_t *v)
+{
+ int t;
+
+ __asm__ __volatile__(
+"1: lwarx %0,0,%2 # local_add_return\n\
+ add %0,%1,%0\n"
+ PPC405_ERR77(0,%2)
+" stwcx. %0,0,%2 \n\
+ bne- 1b"
+ : "=&r" (t)
+ : "r" (a), "r" (&v->counter)
+ : "cc", "memory");
+
+ return t;
+}
+
+#define local_add_negative(a, v) (local_add_return((a), (v)) < 0)
+
+static __inline__ int local_sub_return(int a, local_t *v)
+{
+ int t;
+
+ __asm__ __volatile__(
+"1: lwarx %0,0,%2 # local_sub_return\n\
+ subf %0,%1,%0\n"
+ PPC405_ERR77(0,%2)
+" stwcx. %0,0,%2 \n\
+ bne- 1b"
+ : "=&r" (t)
+ : "r" (a), "r" (&v->counter)
+ : "cc", "memory");
+
+ return t;
+}
+
+static __inline__ int local_inc_return(local_t *v)
+{
+ int t;
+
+ __asm__ __volatile__(
+"1: lwarx %0,0,%1 # local_inc_return\n\
+ addic %0,%0,1\n"
+ PPC405_ERR77(0,%1)
+" stwcx. %0,0,%1 \n\
+ bne- 1b"
+ : "=&r" (t)
+ : "r" (&v->counter)
+ : "cc", "memory");
+
+ return t;
+}
+
+/*
+ * local_inc_and_test - increment and test
+ * @v: pointer of type local_t
+ *
+ * Atomically increments @v by 1
+ * and returns true if the result is zero, or false for all
+ * other cases.
+ */
+#define local_inc_and_test(v) (local_inc_return(v) == 0)
+
+static __inline__ int local_dec_return(local_t *v)
+{
+ int t;
+
+ __asm__ __volatile__(
+"1: lwarx %0,0,%1 # local_dec_return\n\
+ addic %0,%0,-1\n"
+ PPC405_ERR77(0,%1)
+" stwcx. %0,0,%1\n\
+ bne- 1b"
+ : "=&r" (t)
+ : "r" (&v->counter)
+ : "cc", "memory");
+
+ return t;
+}
+
+#define local_cmpxchg(v, o, n) \
+ ((__typeof__((v)->counter))cmpxchg(&((v)->counter), (o), (n)))
+#define local_xchg(v, new) (xchg(&((v)->counter), new))
+
+/**
+ * local_add_unless - add unless the number is a given value
+ * @v: pointer of type local_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns non-zero if @v was not @u, and zero otherwise.
+ */
+static __inline__ int local_add_unless(local_t *v, int a, int u)
+{
+ int t;
+
+ __asm__ __volatile__ (
+"1: lwarx %0,0,%1 # local_add_unless\n\
+ cmpw 0,%0,%3 \n\
+ beq- 2f \n\
+ add %0,%2,%0 \n"
+ PPC405_ERR77(0,%2)
+" stwcx. %0,0,%1 \n\
+ bne- 1b \n"
+" subf %0,%2,%0 \n\
+2:"
+ : "=&r" (t)
+ : "r" (&v->counter), "r" (a), "r" (u)
+ : "cc", "memory");
+
+ return t != u;
+}
+
+#define local_inc_not_zero(v) local_add_unless((v), 1, 0)
+
+#define local_sub_and_test(a, v) (local_sub_return((a), (v)) == 0)
+#define local_dec_and_test(v) (local_dec_return((v)) == 0)
+
+/*
+ * Atomically test *v and decrement if it is greater than 0.
+ * The function returns the old value of *v minus 1.
+ */
+static __inline__ int local_dec_if_positive(local_t *v)
+{
+ int t;
+
+ __asm__ __volatile__(
+"1: lwarx %0,0,%1 # local_dec_if_positive\n\
+ addic. %0,%0,-1\n\
+ blt- 2f\n"
+ PPC405_ERR77(0,%1)
+" stwcx. %0,0,%1\n\
+ bne- 1b"
+ "\n\
+2:" : "=&r" (t)
+ : "r" (&v->counter)
+ : "cc", "memory");
+
+ return t;
+}
+
+#else /* __powerpc64__ */
+
+static __inline__ long local_add_return(long a, local_t *v)
+{
+ long t;
+
+ __asm__ __volatile__(
+"1: ldarx %0,0,%2 # local_add_return\n\
+ add %0,%1,%0\n\
+ stdcx. %0,0,%2 \n\
+ bne- 1b"
+ : "=&r" (t)
+ : "r" (a), "r" (&v->counter)
+ : "cc", "memory");
+
+ return t;
+}
+
+#define local_add_negative(a, v) (local_add_return((a), (v)) < 0)
+
+static __inline__ long local_sub_return(long a, local_t *v)
+{
+ long t;
+
+ __asm__ __volatile__(
+"1: ldarx %0,0,%2 # local_sub_return\n\
+ subf %0,%1,%0\n\
+ stdcx. %0,0,%2 \n\
+ bne- 1b"
+ : "=&r" (t)
+ : "r" (a), "r" (&v->counter)
+ : "cc", "memory");
+
+ return t;
+}
+
+static __inline__ long local_inc_return(local_t *v)
+{
+ long t;
+
+ __asm__ __volatile__(
+"1: ldarx %0,0,%1 # local_inc_return\n\
+ addic %0,%0,1\n\
+ stdcx. %0,0,%1 \n\
+ bne- 1b"
+ : "=&r" (t)
+ : "r" (&v->counter)
+ : "cc", "memory");
+
+ return t;
+}
+
+/*
+ * local_inc_and_test - increment and test
+ * @v: pointer of type local_t
+ *
+ * Atomically increments @v by 1
+ * and returns true if the result is zero, or false for all
+ * other cases.
+ */
+#define local_inc_and_test(v) (local_inc_return(v) == 0)
+
+static __inline__ long local_dec_return(local_t *v)
+{
+ long t;
+
+ __asm__ __volatile__(
+"1: ldarx %0,0,%1 # local_dec_return\n\
+ addic %0,%0,-1\n\
+ stdcx. %0,0,%1\n\
+ bne- 1b"
+ : "=&r" (t)
+ : "r" (&v->counter)
+ : "cc", "memory");
+
+ return t;
+}
+
+#define local_sub_and_test(a, v) (local_sub_return((a), (v)) == 0)
+#define local_dec_and_test(v) (local_dec_return((v)) == 0)
+
+/*
+ * Atomically test *v and decrement if it is greater than 0.
+ * The function returns the old value of *v minus 1.
+ */
+static __inline__ long local_dec_if_positive(local_t *v)
+{
+ long t;
+
+ __asm__ __volatile__(
+"1: ldarx %0,0,%1 # local_dec_if_positive\n\
+ addic. %0,%0,-1\n\
+ blt- 2f\n\
+ stdcx. %0,0,%1\n\
+ bne- 1b"
+ "\n\
+2:" : "=&r" (t)
+ : "r" (&v->counter)
+ : "cc", "memory");
+
+ return t;
+}
+
+#define local_cmpxchg(v, o, n) \
+ ((__typeof__((v)->counter))cmpxchg(&((v)->counter), (o), (n)))
+#define local_xchg(v, new) (xchg(&((v)->counter), new))
+
+/**
+ * local_add_unless - add unless the number is a given value
+ * @v: pointer of type local_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as it was not @u.
+ * Returns non-zero if @v was not @u, and zero otherwise.
+ */
+static __inline__ int local_add_unless(atomic_t *v, long a, long u)
+{
+ long t;
+
+ __asm__ __volatile__ (
+"1: ldarx %0,0,%1 # atomic_add_unless\n\
+ cmpd 0,%0,%3 \n\
+ beq- 2f \n\
+ add %0,%2,%0 \n"
+ PPC405_ERR77(0,%2)
+" stdcx. %0,0,%1 \n\
+ bne- 1b \n"
+" subf %0,%2,%0 \n\
+2:"
+ : "=&r" (t)
+ : "r" (&v->counter), "r" (a), "r" (u)
+ : "cc", "memory");
+
+ return t != u;
+}
+
+#define local_inc_not_zero(v) local_add_unless((v), 1, 0)
+
+#endif /* !__powerpc64__ */
+
+/* Use these for per-cpu local_t variables: on some archs they are
+ * much more efficient than these naive implementations. Note they take
+ * a variable, not an address.
+ *
+ * This could be done better if we moved the per cpu data directly
+ * after GS.
+ */
+
+/* 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) \
+ ({ local_t res__; \
+ preempt_disable(); \
+ res__ = (v); \
+ preempt_enable(); \
+ res__; })
+#define cpu_local_wrap(v) \
+ ({ preempt_disable(); \
+ v; \
+ 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))
+
+#endif /* _ARCH_POWERPC_LOCAL_H */
--- a/include/asm-mips/local.h
+++ b/include/asm-mips/local.h
@@ -1,60 +1 @@
-#ifndef _ASM_LOCAL_H
-#define _ASM_LOCAL_H
-
-#include <linux/percpu.h>
-#include <asm/atomic.h>
-
-#ifdef CONFIG_32BIT
-
-typedef atomic_t local_t;
-
-#define LOCAL_INIT(i) ATOMIC_INIT(i)
-#define local_read(v) atomic_read(v)
-#define local_set(v,i) atomic_set(v,i)
-
-#define local_inc(v) atomic_inc(v)
-#define local_dec(v) atomic_dec(v)
-#define local_add(i, v) atomic_add(i, v)
-#define local_sub(i, v) atomic_sub(i, v)
-
-#endif
-
-#ifdef CONFIG_64BIT
-
-typedef atomic64_t local_t;
-
-#define LOCAL_INIT(i) ATOMIC64_INIT(i)
-#define local_read(v) atomic64_read(v)
-#define local_set(v,i) atomic64_set(v,i)
-
-#define local_inc(v) atomic64_inc(v)
-#define local_dec(v) atomic64_dec(v)
-#define local_add(i, v) atomic64_add(i, v)
-#define local_sub(i, v) atomic64_sub(i, v)
-
-#endif
-
-#define __local_inc(v) ((v)->counter++)
-#define __local_dec(v) ((v)->counter--)
-#define __local_add(i,v) ((v)->counter+=(i))
-#define __local_sub(i,v) ((v)->counter-=(i))
-
-/*
- * Use these for per-cpu local_t variables: on some archs they are
- * much more efficient than these naive implementations. Note they take
- * a variable, not an address.
- */
-#define cpu_local_read(v) local_read(&__get_cpu_var(v))
-#define cpu_local_set(v, i) local_set(&__get_cpu_var(v), (i))
-
-#define cpu_local_inc(v) local_inc(&__get_cpu_var(v))
-#define cpu_local_dec(v) local_dec(&__get_cpu_var(v))
-#define cpu_local_add(i, v) local_add((i), &__get_cpu_var(v))
-#define cpu_local_sub(i, v) local_sub((i), &__get_cpu_var(v))
-
-#define __cpu_local_inc(v) __local_inc(&__get_cpu_var(v))
-#define __cpu_local_dec(v) __local_dec(&__get_cpu_var(v))
-#define __cpu_local_add(i, v) __local_add((i), &__get_cpu_var(v))
-#define __cpu_local_sub(i, v) __local_sub((i), &__get_cpu_var(v))
-
-#endif /* _ASM_LOCAL_H */
+#include <asm-generic/local.h>
--- a/include/asm-generic/local.h
+++ b/include/asm-generic/local.h
@@ -33,6 +33,19 @@ #define local_dec(l) atomic_long_dec(&(l
#define local_add(i,l) atomic_long_add((i),(&(l)->a))
#define local_sub(i,l) atomic_long_sub((i),(&(l)->a))
+#define local_sub_and_test(i, l) atomic_long_sub_and_test((i), (&(l)->a))
+#define local_dec_and_test(l) atomic_long_dec_and_test(&(l)->a)
+#define local_inc_and_test(l) atomic_long_inc_and_test(&(l)->a)
+#define local_add_negative(i, l) atomic_long_add_negative((i), (&(l)->a))
+#define local_add_return(i, l) atomic_long_add_return((i), (&(l)->a))
+#define local_sub_return(i, l) atomic_long_sub_return((i), (&(l)->a))
+#define local_inc_return(l) atomic_long_inc_return(&(l)->a)
+
+#define local_cmpxchg(l, old, new) atomic_long_cmpxchg((&(l)->a), (old), (new))
+#define local_xchg(l, new) atomic_long_xchg((&(l)->a), (new))
+#define local_add_unless(l, a, u) atomic_long_add_unless((&(l)->a), (a), (u))
+#define local_inc_not_zero(l) atomic_long_inc_not_zero(&(l)->a)
+
/* Non-atomic variants, ie. preemption disabled and won't be touched
* in interrupt, etc. Some archs can optimize this case well. */
#define __local_inc(l) local_set((l), local_read(l) + 1)
---END---
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