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Subject: Re: [PATCH 3/5] perf_counter: rework ioctl()s
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Ingo Molnar <mingo@elte.hu>, Paul Mackerras <paulus@samba.org>,
       Corey Ashford <cjashfor@linux.vnet.ibm.com>,
       linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>
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	 <20090508170028.837558214@chello.nl>  <200905120158.46314.arnd@arndb.de>
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Date: Tue, 12 May 2009 08:11:40 +0200
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On Tue, 2009-05-12 at 01:58 +0200, Arnd Bergmann wrote:
> On Friday 08 May 2009, Peter Zijlstra wrote:
> > -#define PERF_COUNTER_IOC_ENABLE                _IO ('$', 0)
> > -#define PERF_COUNTER_IOC_DISABLE       _IO ('$', 1)
> > +#define PERF_COUNTER_IOC_ENABLE                _IOW('$', 0, u32)
> > +#define PERF_COUNTER_IOC_DISABLE       _IOW('$', 1, u32)
> >  #define PERF_COUNTER_IOC_REFRESH       _IOW('$', 2, u32)
> > -#define PERF_COUNTER_IOC_RESET         _IO ('$', 3)
> > +#define PERF_COUNTER_IOC_RESET         _IOW('$', 3, u32)
> 
> These ioctl definitions look malformed:
> _IOW('$', 0, u32) means that the ioctl will read a u32 in user
> space pointed to by (u32 __user *)arg, while what perf_ioctl
> actually does is cast arg to a u32. Moreover, exported headers
> should use __u32 instead of u32.
> 
> PERF_COUNTER_IOC_REFRESH apparently was broken already, this
> patch also breaks the other definitions.

Hmm, are you saying that the 3rd argument to unlocked_ioctl is actually
(void __user *) instead of unsigned long?