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From: Felix Domke <tmbinc@elitedvb.net>
To: ppc-dev <linuxppc-dev@ozlabs.org>
Subject: Re: [PATCH] Infinite loop/always true check possible with unsigned counter.
Date: Tue, 10 Jul 2007 02:41:21 +0200	[thread overview]
Message-ID: <4692D5B1.2040209@elitedvb.net> (raw)
In-Reply-To: <18066.53384.449544.952545@cargo.ozlabs.ibm.com>

Paul Mackerras wrote:
>> Fix to correct a possible infinite loop or an always true check when the 
>> unsigned long counter "i" is used in
>> lmb_add_region() in the following for loop:
>> for (i = rgn->cnt-1; i >= 0; i--)
> Unfortunately this won't fix the bug.  Since rgn->cnt is unsigned
> long, the comparison will be done as an unsigned comparison even if i
> is signed.
> Instead, change the loop to go from rgn->cnt down to 1, and in the
> loop body, change all instances of "i+1" to "i", and "i" to "i-1".
What's about

i = rgn->cnt;
while (i--)
...
?

(or  for (i=rgn->cnt; i--; ), if you want a for-loop)


Felix

  reply	other threads:[~2007-07-10  1:05 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-07-09 17:31 [PATCH] Infinite loop/always true check possible with unsigned counter Manish Ahuja
2007-07-09 19:03 ` Manish Ahuja
2007-07-10  0:19   ` Paul Mackerras
2007-07-10  0:41     ` Felix Domke [this message]
2007-07-10  9:46     ` Andreas Schwab
2007-07-10  9:49       ` Paul Mackerras
2007-07-10  9:55         ` Andreas Schwab
2007-07-10 10:08           ` Paul Mackerras
2007-07-10 18:39             ` Manish Ahuja
2007-07-10 23:19               ` Paul Mackerras

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