On 5/10/07, Jesper Juhl <[email protected]> wrote:
On 10/05/07, Satyam Sharma <[email protected]> wrote:
> On 5/10/07, Jesper Juhl <[email protected]> wrote:
> > [snip]
> > you write: "... that the variable could be changed outside of the
> > current thread of execution ..."
> >
> > I suggest: "... that the variable could be changed outside of the
> > current thread of execution - a sort of simple atomic variable ..."
>
> I'm not so sure here. Why would any C programmer (worth his weight in
> salt) think that volatile objects are automatically _atomic_? At
I honestly don't really know, but I've encountered that confusion a
few times. Both from friends who (for some reason) believed that and
from documents on the web that implied it, aparently it's a common
confusion - a few examples:
http://lists.freebsd.org/pipermail/freebsd-perl/2004-June/000124.html
"... volatile (atomic) fixes the problem. ..."
http://blogs.msdn.com/ricom/archive/2006/04/28/586406.aspx
"That's the point of the volatile keyword. It makes sure that
the line "dict = d;" is atomic."
http://forum.java.sun.com/thread.jspa?threadID=5126877&start=0
"A volatile variable is also guaranteed to be read or written
as an atomic operation ..." (yes, this link talks about Java, which I
don't know, but if java volatile means atomic, that might explain why
some people assume the same for C).
Perl / Microsoft / Java programmers are probably not worth their
weight in salt anyway :-)
I'm not an expert in any of the above platforms either, so don't know
if the semantics of "volatile" in those other languages are different
from that in C -- and this document clearly applies to only the kernel
(and thus C). But if this volatile == atomic disease is indeed common
among _C_ programmers too, then your suggested addition would make
sense.
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