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Re: [Ltt-dev] [PATCH 5/10] local_t : MIPS

To: linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>, Ingo Molnar <mingo@redhat.com>, Greg Kroah-Hartman <gregkh@suse.de>, Christoph Hellwig <hch@infradead.org>, Linux-MIPS <linux-mips@linux-mips.org>
Subject: Re: [Ltt-dev] [PATCH 5/10] local_t : MIPS
From: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Date: Thu, 21 Dec 2006 09:04:11 -0500
Cc: Douglas Niehaus <niehaus@eecs.ku.edu>, "Martin J. Bligh" <mbligh@mbligh.org>, ltt-dev@shafik.org, Thomas Gleixner <tglx@linutronix.de>, systemtap@sources.redhat.com
In-reply-to: <20061221002508.GU28643@Krystal>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20061221001545.GP28643@Krystal> <20061221002508.GU28643@Krystal>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.13 (2006-08-11)
Sorry, I meant MIPS.

* Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca) wrote:
> ia64 architecture local_t extension.
> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
> 
> --- a/include/asm-mips/system.h
> +++ b/include/asm-mips/system.h
> @@ -253,6 +253,58 @@ static inline unsigned long __cmpxchg_u3
>       return retval;
>  }
>  
> +static inline unsigned long __cmpxchg_u32_local(volatile int * m,
> +     unsigned long old, unsigned long new)
> +{
> +     __u32 retval;
> +
> +     if (cpu_has_llsc && R10000_LLSC_WAR) {
> +             __asm__ __volatile__(
> +             "       .set    push                                    \n"
> +             "       .set    noat                                    \n"
> +             "       .set    mips3                                   \n"
> +             "1:     ll      %0, %2                  # __cmpxchg_u32 \n"
> +             "       bne     %0, %z3, 2f                             \n"
> +             "       .set    mips0                                   \n"
> +             "       move    $1, %z4                                 \n"
> +             "       .set    mips3                                   \n"
> +             "       sc      $1, %1                                  \n"
> +             "       beqzl   $1, 1b                                  \n"
> +             "2:                                                     \n"
> +             "       .set    pop                                     \n"
> +             : "=&r" (retval), "=R" (*m)
> +             : "R" (*m), "Jr" (old), "Jr" (new)
> +             : "memory");
> +     } else if (cpu_has_llsc) {
> +             __asm__ __volatile__(
> +             "       .set    push                                    \n"
> +             "       .set    noat                                    \n"
> +             "       .set    mips3                                   \n"
> +             "1:     ll      %0, %2                  # __cmpxchg_u32 \n"
> +             "       bne     %0, %z3, 2f                             \n"
> +             "       .set    mips0                                   \n"
> +             "       move    $1, %z4                                 \n"
> +             "       .set    mips3                                   \n"
> +             "       sc      $1, %1                                  \n"
> +             "       beqz    $1, 1b                                  \n"
> +             "2:                                                     \n"
> +             "       .set    pop                                     \n"
> +             : "=&r" (retval), "=R" (*m)
> +             : "R" (*m), "Jr" (old), "Jr" (new)
> +             : "memory");
> +     } else {
> +             unsigned long flags;
> +
> +             local_irq_save(flags);
> +             retval = *m;
> +             if (retval == old)
> +                     *m = new;
> +             local_irq_restore(flags);       /* implies memory barrier  */
> +     }
> +
> +     return retval;
> +}
> +
>  #ifdef CONFIG_64BIT
>  static inline unsigned long __cmpxchg_u64(volatile int * m, unsigned long 
> old,
>       unsigned long new)
> @@ -303,10 +355,62 @@ static inline unsigned long __cmpxchg_u6
>  
>       return retval;
>  }
> +
> +static inline unsigned long __cmpxchg_u64_local(volatile int * m,
> +     unsigned long old, unsigned long new)
> +{
> +     __u64 retval;
> +
> +     if (cpu_has_llsc && R10000_LLSC_WAR) {
> +             __asm__ __volatile__(
> +             "       .set    push                                    \n"
> +             "       .set    noat                                    \n"
> +             "       .set    mips3                                   \n"
> +             "1:     lld     %0, %2                  # __cmpxchg_u64 \n"
> +             "       bne     %0, %z3, 2f                             \n"
> +             "       move    $1, %z4                                 \n"
> +             "       scd     $1, %1                                  \n"
> +             "       beqzl   $1, 1b                                  \n"
> +             "2:                                                     \n"
> +             "       .set    pop                                     \n"
> +             : "=&r" (retval), "=R" (*m)
> +             : "R" (*m), "Jr" (old), "Jr" (new)
> +             : "memory");
> +     } else if (cpu_has_llsc) {
> +             __asm__ __volatile__(
> +             "       .set    push                                    \n"
> +             "       .set    noat                                    \n"
> +             "       .set    mips3                                   \n"
> +             "1:     lld     %0, %2                  # __cmpxchg_u64 \n"
> +             "       bne     %0, %z3, 2f                             \n"
> +             "       move    $1, %z4                                 \n"
> +             "       scd     $1, %1                                  \n"
> +             "       beqz    $1, 1b                                  \n"
> +             "2:                                                     \n"
> +             "       .set    pop                                     \n"
> +             : "=&r" (retval), "=R" (*m)
> +             : "R" (*m), "Jr" (old), "Jr" (new)
> +             : "memory");
> +     } else {
> +             unsigned long flags;
> +
> +             local_irq_save(flags);
> +             retval = *m;
> +             if (retval == old)
> +                     *m = new;
> +             local_irq_restore(flags);       /* implies memory barrier  */
> +     }
> +
> +     return retval;
> +}
> +
>  #else
>  extern unsigned long __cmpxchg_u64_unsupported_on_32bit_kernels(
>       volatile int * m, unsigned long old, unsigned long new);
>  #define __cmpxchg_u64 __cmpxchg_u64_unsupported_on_32bit_kernels
> +extern unsigned long __cmpxchg_u64_local_unsupported_on_32bit_kernels(
> +     volatile int * m, unsigned long old, unsigned long new);
> +#define __cmpxchg_u64_local __cmpxchg_u64_local_unsupported_on_32bit_kernels
>  #endif
>  
>  /* This function doesn't exist, so you'll get a linker error
> @@ -326,7 +430,26 @@ static inline unsigned long __cmpxchg(vo
>       return old;
>  }
>  
> -#define cmpxchg(ptr,old,new) ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned 
> long)(old), (unsigned long)(new),sizeof(*(ptr))))
> +static inline unsigned long __cmpxchg_local(volatile void * ptr,
> +     unsigned long old, unsigned long new, int size)
> +{
> +     switch (size) {
> +     case 4:
> +             return __cmpxchg_u32_local(ptr, old, new);
> +     case 8:
> +             return __cmpxchg_u64_local(ptr, old, new);
> +     }
> +     __cmpxchg_called_with_bad_pointer();
> +     return old;
> +}
> +
> +#define cmpxchg(ptr,old,new) \
> +     ((__typeof__(*(ptr)))__cmpxchg((ptr), \
> +             (unsigned long)(old), (unsigned long)(new),sizeof(*(ptr))))
> +
> +#define cmpxchg_local(ptr,old,new) \
> +     ((__typeof__(*(ptr)))__cmpxchg_local((ptr), \
> +             (unsigned long)(old), (unsigned long)(new),sizeof(*(ptr))))
>  
>  extern void set_handler (unsigned long offset, void *addr, unsigned long 
> len);
>  extern void set_uncached_handler (unsigned long offset, void *addr, unsigned 
> long len);
> --- a/include/asm-mips/local.h
> +++ b/include/asm-mips/local.h
> @@ -1,60 +1,527 @@
> -#ifndef _ASM_LOCAL_H
> -#define _ASM_LOCAL_H
> +#ifndef _ARCH_POWERPC_LOCAL_H
> +#define _ARCH_POWERPC_LOCAL_H
>  
>  #include <linux/percpu.h>
>  #include <asm/atomic.h>
>  
> -#ifdef CONFIG_32BIT
> +typedef struct
> +{
> +     local_long_t a;
> +} local_t;
>  
> -typedef atomic_t local_t;
> +#define LOCAL_INIT(i)        { local_LONG_INIT(i) }
>  
> -#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_read(l)        local_long_read(&(l)->a)
> +#define local_set(l,i)       local_long_set(&(l)->a, (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)
> +#define local_add(i,l)       local_long_add((i),(&(l)->a))
> +#define local_sub(i,l)       local_long_sub((i),(&(l)->a))
> +#define local_inc(l) local_long_inc(&(l)->a)
> +#define local_dec(l) local_long_dec(&(l)->a)
>  
> -#endif
>  
> -#ifdef CONFIG_64BIT
> +#ifndef CONFIG_64BITS
>  
> -typedef atomic64_t local_t;
> +/*
> + * Same as above, but return the result value
> + */
> +static __inline__ int local_add_return(int i, local_t * l)
> +{
> +     unsigned long result;
> +
> +     if (cpu_has_llsc && R10000_LLSC_WAR) {
> +             unsigned long temp;
> +
> +             __asm__ __volatile__(
> +             "       .set    mips3                                   \n"
> +             "1:     ll      %1, %2          # local_add_return      \n"
> +             "       addu    %0, %1, %3                              \n"
> +             "       sc      %0, %2                                  \n"
> +             "       beqzl   %0, 1b                                  \n"
> +             "       addu    %0, %1, %3                              \n"
> +             "       .set    mips0                                   \n"
> +             : "=&r" (result), "=&r" (temp), "=m" (&(l->a.counter))
> +             : "Ir" (i), "m" (&(l->a.counter))
> +             : "memory");
> +     } else if (cpu_has_llsc) {
> +             unsigned long temp;
> +
> +             __asm__ __volatile__(
> +             "       .set    mips3                                   \n"
> +             "1:     ll      %1, %2          # local_add_return      \n"
> +             "       addu    %0, %1, %3                              \n"
> +             "       sc      %0, %2                                  \n"
> +             "       beqz    %0, 1b                                  \n"
> +             "       addu    %0, %1, %3                              \n"
> +             "       .set    mips0                                   \n"
> +             : "=&r" (result), "=&r" (temp), "=m" (&(l->a.counter))
> +             : "Ir" (i), "m" (&(l->a.counter))
> +             : "memory");
> +     } else {
> +             unsigned long flags;
> +
> +             local_irq_save(flags);
> +             result = &(l->a.counter);
> +             result += i;
> +             &(l->a.counter) = result;
> +             local_irq_restore(flags);
> +     }
> +
> +     return result;
> +}
> +
> +static __inline__ int local_sub_return(int i, local_t * l)
> +{
> +     unsigned long result;
> +
> +     if (cpu_has_llsc && R10000_LLSC_WAR) {
> +             unsigned long temp;
> +
> +             __asm__ __volatile__(
> +             "       .set    mips3                                   \n"
> +             "1:     ll      %1, %2          # local_sub_return      \n"
> +             "       subu    %0, %1, %3                              \n"
> +             "       sc      %0, %2                                  \n"
> +             "       beqzl   %0, 1b                                  \n"
> +             "       subu    %0, %1, %3                              \n"
> +             "       .set    mips0                                   \n"
> +             : "=&r" (result), "=&r" (temp), "=m" (&(l->a.counter))
> +             : "Ir" (i), "m" (&(l->a.counter))
> +             : "memory");
> +     } else if (cpu_has_llsc) {
> +             unsigned long temp;
> +
> +             __asm__ __volatile__(
> +             "       .set    mips3                                   \n"
> +             "1:     ll      %1, %2          # local_sub_return      \n"
> +             "       subu    %0, %1, %3                              \n"
> +             "       sc      %0, %2                                  \n"
> +             "       beqz    %0, 1b                                  \n"
> +             "       subu    %0, %1, %3                              \n"
> +             "       .set    mips0                                   \n"
> +             : "=&r" (result), "=&r" (temp), "=m" (&(l->a.counter))
> +             : "Ir" (i), "m" (&(l->a.counter))
> +             : "memory");
> +     } else {
> +             unsigned long flags;
> +
> +             local_irq_save(flags);
> +             result = &(l->a.counter);
> +             result -= i;
> +             &(l->a.counter) = result;
> +             local_irq_restore(flags);
> +     }
> +
> +     return result;
> +}
> +
> +/*
> + * local_sub_if_positive - conditionally subtract integer from atomic 
> variable
> + * @i: integer value to subtract
> + * @l: pointer of type local_t
> + *
> + * Atomically test @l and subtract @i if @l is greater or equal than @i.
> + * The function returns the old value of @l minus @i.
> + */
> +static __inline__ int local_sub_if_positive(int i, local_t * l)
> +{
> +     unsigned long result;
> +
> +     if (cpu_has_llsc && R10000_LLSC_WAR) {
> +             unsigned long temp;
> +
> +             __asm__ __volatile__(
> +             "       .set    mips3                                   \n"
> +             "1:     ll      %1, %2          # local_sub_if_positive\n"
> +             "       subu    %0, %1, %3                              \n"
> +             "       bltz    %0, 1f                                  \n"
> +             "       sc      %0, %2                                  \n"
> +             "       .set    noreorder                               \n"
> +             "       beqzl   %0, 1b                                  \n"
> +             "        subu   %0, %1, %3                              \n"
> +             "       .set    reorder                                 \n"
> +             "1:                                                     \n"
> +             "       .set    mips0                                   \n"
> +             : "=&r" (result), "=&r" (temp), "=m" (&(l->a.counter))
> +             : "Ir" (i), "m" (&(l->a.counter))
> +             : "memory");
> +     } else if (cpu_has_llsc) {
> +             unsigned long temp;
> +
> +             __asm__ __volatile__(
> +             "       .set    mips3                                   \n"
> +             "1:     ll      %1, %2          # local_sub_if_positive\n"
> +             "       subu    %0, %1, %3                              \n"
> +             "       bltz    %0, 1f                                  \n"
> +             "       sc      %0, %2                                  \n"
> +             "       .set    noreorder                               \n"
> +             "       beqz    %0, 1b                                  \n"
> +             "        subu   %0, %1, %3                              \n"
> +             "       .set    reorder                                 \n"
> +             "1:                                                     \n"
> +             "       .set    mips0                                   \n"
> +             : "=&r" (result), "=&r" (temp), "=m" (&(l->a.counter))
> +             : "Ir" (i), "m" (&(l->a.counter))
> +             : "memory");
> +     } else {
> +             unsigned long flags;
> +
> +             local_irq_save(flags);
> +             result = &(l->a.counter);
> +             result -= i;
> +             if (result >= 0)
> +                     &(l->a.counter) = result;
> +             local_irq_restore(flags);
> +     }
> +
> +     return result;
> +}
> +
> +#define local_cmpxchg(l, o, n) \
> +     ((long)cmpxchg(&((l)->a.counter), (o), (n)))
> +#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);                                      \
> +     while (c != (u) && (old = local_cmpxchg((l), c, c + (a))) != c) \
> +             c = old;                                        \
> +     c != (u);                                               \
> +})
> +#define local_inc_not_zero(l) local_add_unless((l), 1, 0)
> +
> +#define local_dec_return(l) local_sub_return(1,(l))
> +#define local_inc_return(l) local_add_return(1,(l))
> +
> +/*
> + * 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.
> + */
> +#define local_sub_and_test(i,l) (local_sub_return((i), (l)) == 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.
> + */
> +#define local_inc_and_test(l) (local_inc_return(l) == 0)
> +
> +/*
> + * local_dec_and_test - decrement by 1 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.
> + */
> +#define local_dec_and_test(l) (local_sub_return(1, (l)) == 0)
> +
> +/*
> + * local_dec_if_positive - decrement by 1 if old value positive
> + * @l: pointer of type local_t
> + */
> +#define local_dec_if_positive(l)     local_sub_if_positive(1, l)
> +
> +/*
> + * 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.
> + */
> +#define local_add_negative(i,l) (local_add_return(i, (l)) < 0)
> +
> +#else /* CONFIG_64BITS */
>  
> -#define LOCAL_INIT(i)        ATOMIC64_INIT(i)
> -#define local_read(v)        atomic64_read(v)
> -#define local_set(v,i)       atomic64_set(v,i)
> +/*
> + * Same as above, but return the result value
> + */
> +static __inline__ long local_add_return(long i, local_t * l)
> +{
> +     unsigned long result;
> +
> +     if (cpu_has_llsc && R10000_LLSC_WAR) {
> +             unsigned long temp;
> +
> +             __asm__ __volatile__(
> +             "       .set    mips3                                   \n"
> +             "1:     lld     %1, %2          # local_add_return      \n"
> +             "       addu    %0, %1, %3                              \n"
> +             "       scd     %0, %2                                  \n"
> +             "       beqzl   %0, 1b                                  \n"
> +             "       addu    %0, %1, %3                              \n"
> +             "       .set    mips0                                   \n"
> +             : "=&r" (result), "=&r" (temp), "=m" (&(l->a.counter))
> +             : "Ir" (i), "m" (&(l->a.counter))
> +             : "memory");
> +     } else if (cpu_has_llsc) {
> +             unsigned long temp;
> +
> +             __asm__ __volatile__(
> +             "       .set    mips3                                   \n"
> +             "1:     lld     %1, %2          # local_add_return      \n"
> +             "       addu    %0, %1, %3                              \n"
> +             "       scd     %0, %2                                  \n"
> +             "       beqz    %0, 1b                                  \n"
> +             "       addu    %0, %1, %3                              \n"
> +             "       .set    mips0                                   \n"
> +             : "=&r" (result), "=&r" (temp), "=m" (&(l->a.counter))
> +             : "Ir" (i), "m" (&(l->a.counter))
> +             : "memory");
> +     } else {
> +             unsigned long flags;
> +
> +             local_irq_save(flags);
> +             result = &(l->a.counter);
> +             result += i;
> +             &(l->a.counter) = result;
> +             local_irq_restore(flags);
> +     }
>  
> -#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)
> +     return result;
> +}
>  
> -#endif
> +static __inline__ long local_sub_return(long i, local_t * l)
> +{
> +     unsigned long result;
>  
> -#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))
> +     if (cpu_has_llsc && R10000_LLSC_WAR) {
> +             unsigned long temp;
> +
> +             __asm__ __volatile__(
> +             "       .set    mips3                                   \n"
> +             "1:     lld     %1, %2          # local_sub_return      \n"
> +             "       subu    %0, %1, %3                              \n"
> +             "       scd     %0, %2                                  \n"
> +             "       beqzl   %0, 1b                                  \n"
> +             "       subu    %0, %1, %3                              \n"
> +             "       .set    mips0                                   \n"
> +             : "=&r" (result), "=&r" (temp), "=m" (&(l->a.counter))
> +             : "Ir" (i), "m" (&(l->a.counter))
> +             : "memory");
> +     } else if (cpu_has_llsc) {
> +             unsigned long temp;
> +
> +             __asm__ __volatile__(
> +             "       .set    mips3                                   \n"
> +             "1:     lld     %1, %2          # local_sub_return      \n"
> +             "       subu    %0, %1, %3                              \n"
> +             "       scd     %0, %2                                  \n"
> +             "       beqz    %0, 1b                                  \n"
> +             "       subu    %0, %1, %3                              \n"
> +             "       .set    mips0                                   \n"
> +             : "=&r" (result), "=&r" (temp), "=m" (&(l->a.counter))
> +             : "Ir" (i), "m" (&(l->a.counter))
> +             : "memory");
> +     } else {
> +             unsigned long flags;
> +
> +             local_irq_save(flags);
> +             result = &(l->a.counter);
> +             result -= i;
> +             &(l->a.counter) = result;
> +             local_irq_restore(flags);
> +     }
> +
> +     return result;
> +}
>  
>  /*
> - * Use these for per-cpu local_t variables: on some archs they are
> + * local_sub_if_positive - conditionally subtract integer from atomic 
> variable
> + * @i: integer value to subtract
> + * @l: pointer of type local_t
> + *
> + * Atomically test @l and subtract @i if @l is greater or equal than @i.
> + * The function returns the old value of @l minus @i.
> + */
> +static __inline__ long local_sub_if_positive(long i, local_t * l)
> +{
> +     unsigned long result;
> +
> +     if (cpu_has_llsc && R10000_LLSC_WAR) {
> +             unsigned long temp;
> +
> +             __asm__ __volatile__(
> +             "       .set    mips3                                   \n"
> +             "1:     lld     %1, %2          # local_sub_if_positive\n"
> +             "       dsubu   %0, %1, %3                              \n"
> +             "       bltz    %0, 1f                                  \n"
> +             "       scd     %0, %2                                  \n"
> +             "       .set    noreorder                               \n"
> +             "       beqzl   %0, 1b                                  \n"
> +             "        dsubu  %0, %1, %3                              \n"
> +             "       .set    reorder                                 \n"
> +             "1:                                                     \n"
> +             "       .set    mips0                                   \n"
> +             : "=&r" (result), "=&r" (temp), "=m" (&(l->a.counter))
> +             : "Ir" (i), "m" (&(l->a.counter))
> +             : "memory");
> +     } else if (cpu_has_llsc) {
> +             unsigned long temp;
> +
> +             __asm__ __volatile__(
> +             "       .set    mips3                                   \n"
> +             "1:     lld     %1, %2          # local_sub_if_positive\n"
> +             "       dsubu   %0, %1, %3                              \n"
> +             "       bltz    %0, 1f                                  \n"
> +             "       scd     %0, %2                                  \n"
> +             "       .set    noreorder                               \n"
> +             "       beqz    %0, 1b                                  \n"
> +             "        dsubu  %0, %1, %3                              \n"
> +             "       .set    reorder                                 \n"
> +             "1:                                                     \n"
> +             "       .set    mips0                                   \n"
> +             : "=&r" (result), "=&r" (temp), "=m" (&(l->a.counter))
> +             : "Ir" (i), "m" (&(l->a.counter))
> +             : "memory");
> +     } else {
> +             unsigned long flags;
> +
> +             local_irq_save(flags);
> +             result = &(l->a.counter);
> +             result -= i;
> +             if (result >= 0)
> +                     &(l->a.counter) = result;
> +             local_irq_restore(flags);
> +     }
> +
> +     return result;
> +}
> +
> +
> +#define local_cmpxchg(l, o, n) \
> +     ((long)cmpxchg(&((l)->a.counter), (o), (n)))
> +#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);                                      \
> +     while (c != (u) && (old = local_cmpxchg((l), c, c + (a))) != c) \
> +             c = old;                                        \
> +     c != (u);                                               \
> +})
> +#define local_inc_not_zero(l) local_add_unless((l), 1, 0)
> +
> +#define local_dec_return(l) local_sub_return(1,(l))
> +#define local_inc_return(l) local_add_return(1,(l))
> +
> +/*
> + * 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.
> + */
> +#define local_sub_and_test(i,l) (local_sub_return((i), (l)) == 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.
> + */
> +#define local_inc_and_test(l) (local_inc_return(l) == 0)
> +
> +/*
> + * local_dec_and_test - decrement by 1 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.
> + */
> +#define local_dec_and_test(l) (local_sub_return(1, (l)) == 0)
> +
> +/*
> + * local_dec_if_positive - decrement by 1 if old value positive
> + * @l: pointer of type local_t
> + */
> +#define local_dec_if_positive(l)     local_sub_if_positive(1, l)
> +
> +/*
> + * 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.
> + */
> +#define local_add_negative(i,l) (local_add_return(i, (l)) < 0)
> +
> +#endif /* !CONFIG_64BITS */
> +
> +
> +/* 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.
>   */
> -#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 __local_inc(l)               ((l)->a.counter++)
> +#define __local_dec(l)               ((l)->a.counter++)
> +#define __local_add(i,l)     ((l)->a.counter+=(i))
> +#define __local_sub(i,l)     ((l)->a.counter-=(i))
> +
> +/* 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(l)          \
> +     ({ local_t res__;               \
> +        preempt_disable();           \
> +        res__ = (l);                 \
> +        preempt_enable();            \
> +        res__; })
> +#define cpu_local_wrap(l)            \
> +     ({ preempt_disable();           \
> +        l;                           \
> +        preempt_enable(); })         \
> +
> +#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(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(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 /* _ASM_LOCAL_H */
> +#endif /* _ARCH_POWERPC_LOCAL_H */
> 

-- 
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