Re: [PATCH] [8/7] oprofile - dcookies need to use u32

From: David S. Miller (davem@redhat.com)
Date: Tue Oct 15 2002 - 21:00:19 EST


   From: Ulrich Weigand <weigand@immd1.informatik.uni-erlangen.de>
   Date: Wed, 16 Oct 2002 03:56:10 +0200 (MET DST)

   + return (u32)dentry;
   
   Um, isn't this supposed to uniquely identify the dentry?
   On a platform with 64-bit pointers there's now the theoretical
   possibility of different dentries getting the same cookie ...

That's true.

We dealt with this (trying to use a kernel pointer as a cache held by
userspace) in tcp_diag by making the actual object opaque. It was
actually two u32's, and that way it worked independant of kernel
vs. user word size.

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