Re: [PATCH 3/5] perf_counter: rework ioctl()s

From: Paul Mackerras
Date: Tue May 12 2009 - 02:22:37 EST


Peter Zijlstra writes:

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

He's saying (correctly) that using _IOR or _IOW implies that the ioctl
is going to read or write the memory location pointed to by the 3rd
argument to unlocked_ioctl. If the 3rd argument is just a number, not
an address, I believe you should use _IO.

Paul.
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