Re: [head tinderbox] failure on sparc64/sun4v

On Wed, Jun 03, 2009 at 02:15:55PM +0400, Eygene Ryabinkin wrote:
> Wed, Jun 03, 2009 at 01:54:30PM +0400, Eygene Ryabinkin wrote:
> > KTR's case seems to be wrong for PCPU_NAME_LEN larger than 24 bytes.
> > Just now we won't be able to reach this with the current definition
> > for PCPU_NAME_LEN, but some day (N - (PCPU_NAME_LEN + 7)/8) can
> > become negative and that's bad.
> 
> And while I am here: definition for PCPU_NAME_LEN seems to be wrong.
> It is intended to fit ("CPU %d", cpuid) where cpuid <= MAXCPU.  If this
> is correct, then (sys/sys/pcpu.h, line 57)
> 
>  1. sizeof(__XSTRING(MAXCPU) + 1) is a typo: typeof(__XSTRING(...) + 1)
>     is 'char *', so sizeof() will return the size of the pointer, not
>     the size of the string contents.  The proper expression should be
>     'sizeof(__XSTRING(MAXCPU)) + 1'.
> 
>  2. one should not add one, but substract it: sizeof() accounts for the
>     trailing '\0' and we have two sizeof's, so the size of one '\0'
>     should be substracted -- this will give the maximal string buffer
>     length for CPU with its number, no less, no more.
> 
> Does the attached patch looks sane?
> diff --git a/sys/sys/pcpu.h b/sys/sys/pcpu.h
> index 63c3fa3..98705eb 100644
> --- a/sys/sys/pcpu.h
> +++ b/sys/sys/pcpu.h
> _at__at_ -54,7 +54,7 _at__at_ struct rm_queue {
>  	struct rm_queue* volatile rmq_prev;
>  };
>  
> -#define	PCPU_NAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU) + 1))
> +#define	PCPU_NAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1)
>  
>  
>  /*

This looks correct to me. Jeff?

Marius