Re: [PATCH 1/2] nptl: Remove __ASSUME_SET_ROBUST_LIST

[Florian Weimer <fweimer at redhat dot com>]

On 04/19/2017 07:38 PM, Adhemerval Zanella wrote:
> On Wed, Apr 19, 2017 at 12:28 PM, Florian Weimer <fweimer@redhat.com> wrote:
> > On 04/19/2017 04:17 PM, Adhemerval Zanella wrote:
> > > The problem is kernel supports for some architecture depends of kernel
> > > config
> > > and the underlying hardware revision/model.
> >
> >
> > I understand that.  But I have seen a lot of use of robust mutexes lately,
> > and I'm sure these developers aren't aware that the mutexes aren't portable
> > across GNU/Linux (the Linux architecture subset supported by glibc).
> >
> > I expect it's like the missing accept4 system call—you need to provide the
> > set_robust_list system call in the kernel if you want to a working, modern
> > system.
>
> But my point is with current minimum supported kernel version for some
> architectures
> we can't simple assume set_robust_list support and even bumping minimum kernel
> version for some architectures also do not solve the issue (on mips
> for instance).

Hmm, maybe you are right, and we have to keep things this way for now.

But I don't like that your patch reintroduces the conditional code.  You 
could use

#define __set_robust_list_avail 1

for the __ASSUME_SET_ROBUST_LIST case to reduce clutter, and let GCC do 
the rest.

Thanks,
Florian