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Date: Thu, 6 Jul 2006 14:07:51 -0700 (PDT)
From: Linus Torvalds <torvalds@osdl.org>
To: Jan Engelhardt <jengelh@linux01.gwdg.de>
cc: Jeremy Fitzhardinge <jeremy@goop.org>,
       "linux-os (Dick Johnson)" <linux-os@analogic.com>,
       Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@osdl.org>,
       linux-kernel@vger.kernel.org, arjan@infradead.org
Subject: Re: [patch] spinlocks: remove 'volatile'
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On Thu, 6 Jul 2006, Jan Engelhardt wrote:
> >
> > You need to exclude "asm volatile", which is a completely different thing.
> 
> 10077.

Yeah, way too many. 

That said, at least _some_ of them are:

 - casts to volatile inside arch-specific code serquences (ie the _good_ 
   kind of volatile - associated with _code_ rather than data). 

   See for example include/asm-i386/io.h for 100% valid examples of this
   kind of usage.

 - function argument values for functions that need to be able to take an 
   arbitrary pointer ("const volatile void *" is the most permissive 
   argument type - anything else the compiler can complain about you 
   dropping qualifiers)

   See include/asm-i386/bitops.h for examples of this kind of volatile.

So I'd expect that maybe one percent of them are actually valid ;)

And I suspect that a huge majority of the truly crapola ones are in 
drivers. Oh, well..

			Linus