[PATCH 1/9][BZ 16892] Add linux-generic lowlevellock.h

[Chris Metcalf]

On 6/9/2014 4:24 PM, Bernard Ogden wrote:
> +#define lll_futex_timed_wait(futexp, val, timespec, private) \
> +  ({									      \
> +    INTERNAL_SYSCALL_DECL (__err);					      \
> +    long int __ret;							      \
> +    __ret = INTERNAL_SYSCALL (futex, __err, 4, (futexp),		      \
> +			      __lll_private_flag (FUTEX_WAIT, private),	      \
> +			      (val), (timespec));			      \
> +    if(INTERNAL_SYSCALL_ERROR_P (__ret, __err))				      \
> +      __ret = -(INTERNAL_SYSCALL_ERRNO (__ret, __err));			      \
> +    __ret;								      \
> +  })

Style note: space after "if".  And might as well use __glibc_unlikely().

Maybe use an abstraction like INLINE_FUTEX_SYSCALL to capture the INTERNAL_SYSCALL pieces, e.g.

#define INLINE_FUTEX_SYSCALL(name, nr, args...) \
   ({                                                                    \
     INTERNAL_SYSCALL_DECL (__err);                                      \
     long int __ret = INTERNAL_SYSCALL (name, err, nr, args);            \
     if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (__ret, __err)))     \
         __ret = -(INTERNAL_SYSCALL_ERRNO (__ret, __err));               \
     __ret;                                                              \
   })

Then you could use that throughout, e.g. lll_futex_timed_wait() is just a #define for INLINE_FUTEX_SYSCALL(futex, 4, (futexp), __lll_private_flag (FUTEX_WAIT, private), (val), (timespec)) and all the rest of the mechanism stays in INLINE_FUTEX_SYSCALL().

Otherwise, not tested, but both his and the tile-specific changes look OK to me.

-- 
Chris Metcalf, Tilera Corp.
http://www.tilera.com