Re: [PATCH v4 00/15] Add futex2 syscalls

[Greg KH]

On Tue, Jun 08, 2021 at 04:18:42PM +0300, Andrey Semashev wrote:
> On 6/8/21 3:35 PM, Greg KH wrote:
> > On Tue, Jun 08, 2021 at 03:06:48PM +0300, Andrey Semashev wrote:
> > > On 6/8/21 2:13 PM, Greg KH wrote:
> > 
> > > > So what's keeping the futex2 code from doing all that futex1 does so
> > > > that the futex1 code can be deleted internally?
> > > 
> > > I think, André will answer this, but my guess is, as stated above, this is a
> > > lot of work and time while the intermediate version is already useful.
> > 
> > useful to who?  I still do not understand what users will be needing
> > this.  All I can tell is a single userspace program wants to use it, and
> > that is a fork from the real project it was based on and that the
> > maintainers have no plan to merge it back.
> > 
> > So who does need/want this?
> 
> I mentioned C++ std::atomic and Boost.Atomic before. Those need variable
> sized futexes.

And has anyone converted them to use this new api to see if it works
well or not?

As was pointed out to me numerous times when I tried to propose
readfile(), you need a real user that can show and prove it is needed
before we can take new syscalls, especially complex beasts like this
one.

thanks,

greg k-h