Date: Wed, 3 Jun 2009 22:00:13 +0200 From: Marius Strobl <marius@alchemy.franken.de> To: Eygene Ryabinkin <rea-fbsd@codelabs.ru>, jeff@freebsd.org Cc: current@freebsd.org, kmacy@freebsd.org, rwatson@freebsd.org, FreeBSD Tinderbox <tinderbox@freebsd.org>, sparc64@freebsd.org Subject: Re: [head tinderbox] failure on sparc64/sun4v Message-ID: <20090603200013.GB43137@alchemy.franken.de> In-Reply-To: <vGGiriRDUTPxnXzdq/aYGNGLA2U@j4OYE6OL8eALCd4BvSxIfwgoxSc> References: <20090602222445.2F6017302F@freebsd-current.sentex.ca> <mqQn8SFFPOY77oNsI7n1tk5O7LE@10Ilc7MfiXA2JVIRVQpZfk7cTQ4> <rPuoszoUcXlrNmrZFDbbbNJuZzs@XX1fo6zQUfC4h0jjRC6IBz3oNH4> <vGGiriRDUTPxnXzdq/aYGNGLA2U@j4OYE6OL8eALCd4BvSxIfwgoxSc>
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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
> @@ -54,7 +54,7 @@ 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
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