On Tue, Jul 28, 2015 at 10:23:51PM +0200, Thomas Gleixner wrote: > On Mon, 27 Jul 2015, Michael Kerrisk (man-pages) wrote: ... > > FUTEX_REQUEUE (since Linux 2.6.0) > > .\" FIXME(Torvald) Is there some indication that FUTEX_REQUEUE is broken > > .\" in general, or is this comment implicitly speaking about the > > .\" condvar (?) use case? If the latter we might want to weaken the > > .\" advice below a little. > > .\" [Anyone else have input on this?] > > The condvar use case exposes the flaw nicely, but that's pretty much > true for everything which wants a sane requeue operation. In an earlier discussion I argued this point (that FUTURE_REQUEUE is broken and should not be used in new code) and someone argued strongly against... stating that there were legitimate uses for it. Of course I'm struggling to find the thread and the reference at the moment - immensely useful, I know. I'll continue trying to find it and see if it can be useful here. I believe Torvald was on the thread as well. > > > Avoid using this operation. It is broken for its intended > > purpose. Use FUTEX_CMP_REQUEUE instead. > > > > This operation performs the same task as > > FUTEX_CMP_REQUEUE, except that no check is made using the > > value in val3. (The argument val3 is ignored.) > > -- Darren Hart Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
