Hi Michael, On Mon, 16 Sep 2013 10:26:03 +0300 "Michael S. Tsirkin" <m...@redhat.com> wrote: > > On Mon, Sep 16, 2013 at 04:53:44PM +1000, Stephen Rothwell wrote: > > > > On Mon, 16 Sep 2013 13:38:35 +0930 Rusty Russell <ru...@rustcorp.com.au> > > wrote: > > > > > > Predates git, does anyone remember the rationale? > > > > > > ie: > > > int test_bit(int nr, const volatile unsigned long *addr) > > > > Because we sometimes pass volatile pointers to it and gcc will complain > > if you pass a volatile to a non volatile (I think). > > Where are these? I did git grep -W test_bit and looked for volatile, > couldn't find anything.
OK, so it was a bit of a guess. Have you really checked the type of
every address passed to every call of test_bit()?
Second guess: we wanted to make the test_bit access volatile (as opposed
to the datatypes of the objects being tested) so that things like
while (testbit(bit, addr)) {
do_very_little();
}
don't get over optimised (since we are operating in a very threaded
environment that the compiler not might expect).
--
Cheers,
Stephen Rothwell s...@canb.auug.org.au
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