On Tue, 5 Nov 2019, Florian Weimer wrote: > * Thomas Gleixner: > > On Tue, 5 Nov 2019, Florian Weimer wrote: > >> * Shawn Landden: > >> > If this new ABI is used, then bit 1 of the *next pointer of the > >> > user-space robust_list indicates that the futex_offset2 value should > >> > be used in place of the existing futex_offset. > >> > >> The futex interface currently has some races which can only be fixed by > >> API changes. I'm concerned that we sacrifice the last bit for some > >> rather obscure feature. What if we need that bit for fixing the > >> correctness issues? > > > > That current approach is going nowhere and if we change the ABI ever then > > this needs to happen with all *libc folks involved and agreeing. > > > > Out of curiosity, what's the race issue vs. robust list which you are > > trying to solve? > > Sadly I'm not trying to solve them. Here's one of the issues: > > <https://sourceware.org/bugzilla/show_bug.cgi?id=14485> That one seems more a life time problem, i.e. the mutex is destroyed, memory freed and map address reused while another thread was not yet out of the mutex_unlock() call. Nasty. Thanks, tglx
