On Sat, 18 Oct 2014, Davidlohr Bueso wrote:
> On Sat, 2014-10-18 at 13:50 -0700, Linus Torvalds wrote:
> > On Sat, Oct 18, 2014 at 12:58 PM, Davidlohr Bueso <d...@stgolabs.net> wrote:
> > >
> > > And [get/put]_futex_keys() shouldn't even be called for private futexes.
> > > The following patch had some very minor testing on a 60 core box last
> > > night, but passes both Darren's and perf's tests. So I *think* this is
> > > right, but lack of sleep and I overall just don't trust them futexes!
> >
> > Hmm. I don't see the advantage of making the code more complex in
> > order to avoid the functions that are no-ops for the !fshared case?
> >
> > IOW, as far as I can tell, this patch doesn't actually really *change*
> > anything. Am I missing something?
>
> Right, all we do is avoid a NOP, but I don't see how this patch makes
> the code more complex. In fact, the whole idea is to make it easier to
> read and makes the key referencing differences between shared and
> private futexes crystal clear, hoping to mitigate future bugs.
I tend to disagree. The current code is symetric versus get/drop and
you make it unsymetric by avoiding the drop call with a pointless
extra conditional in all call sites.
I really had to look twice to figure out that the patch is correct,
but I really cannot see any value and definitely have a hard time how
this makes the code clearer and would prevent future bugs.
I rather keep it symetric and document the NOP property for private
futexes in both get and drop.
Thanks,
tglx
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
