Date: Wed, 14 Apr 2010 11:28:43 +0200
From: Ingo Molnar <mingo@elte.hu>
To: David Miller <davem@davemloft.net>, git@vger.kernel.org
Cc: imunsie@au1.ibm.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl,
       paulus@samba.org, acme@redhat.com, kosaki.motohiro@jp.fujitsu.com,
       mitake@dcl.info.waseda.ac.jp, rusty@rustcorp.com.au, fweisbec@gmail.com,
       ebmunson@us.ibm.com, Valdis.Kletnieks@vt.edu, amwang@redhat.com,
       tfransosi@gmail.com, mhiramat@redhat.com, xiaoguangrong@cn.fujitsu.com,
       jaswinderrajput@gmail.com, arjan@linux.intel.com,
       hirofumi@mail.parknet.co.jp, efault@gmx.de, tzanussi@gmail.com,
       anton@samba.org, jkacur@redhat.com, lizf@cn.fujitsu.com,
       rostedt@goodmis.org
Subject: Re: [PATCH] perf: Fix endianness argument compatibility
Message-ID: <20100414092843.GD10537@elte.hu>
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* David Miller <davem@davemloft.net> wrote:

> From: "Ian Munsie" <imunsie@au1.ibm.com>
> Date: Tue, 13 Apr 2010 18:37:33 +1000
> 
> > From: Ian Munsie <imunsie@au.ibm.com>
> > 
> > Parsing an option from the command line with OPT_BOOLEAN on a bool data
> > type would not work on a big-endian machine due to the manner in which
> > the boolean was being cast into an int and incremented. For example,
> > running 'perf probe --list' on a PowerPC machine would fail to properly
> > set the list_events bool and would therefore print out the usage
> > information and terminate.
> > 
> > This patch makes OPT_BOOLEAN work as expected with a bool datatype. For
> > cases where the original OPT_BOOLEAN was intentionally being used to
> > increment an int each time it was passed in on the command line, this
> > patch introduces OPT_INCR with the old behaviour of OPT_BOOLEAN (the
> > verbose variable is currently the only such example of this).
> > 
> > I have reviewed every use of OPT_BOOLEAN to verify that a true C99 bool
> > was passed. Where integers were used, I verified that they were only
> > being used for boolean logic and changed them to bools to ensure that
> > they would not be mistakenly used as ints. The major exception was the
> > verbose variable which now uses OPT_INCR instead of OPT_BOOLEAN.
> > 
> > Signed-off-by: Ian Munsie <imunsie@au.ibm.com>
> 
> Thanks for finding and fixing this bug.

Nice fix!

Btw., perf got the option parser from the Git project - i'm wondering how the 
Git folks solved this endianness problem?

	Ingo
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