[head tinderbox] failure on sparc64/sun4v

Eygene Ryabinkin rea-fbsd at codelabs.ru
Wed Jun 3 10:16:00 UTC 2009


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?
-- 
Eygene
 _                ___       _.--.   #
 \`.|\..----...-'`   `-._.-'_.-'`   #  Remember that it is hard
 /  ' `         ,       __.--'      #  to read the on-line manual
 )/' _/     \   `-_,   /            #  while single-stepping the kernel.
 `-'" `"\_  ,_.-;_.-\_ ',  fsc/as   #
     _.-'_./   {_.'   ; /           #    -- FreeBSD Developers handbook
    {_.-``-'         {_/            #
-------------- next part --------------
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)
 
 
 /*


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