Should glibc be fully reentrant? -- No. (Roland was right).

[Ondřej Bílka]

On Fri, Dec 12, 2014 at 10:50:19AM +0100, Florian Weimer wrote:
> On 12/11/2014 03:11 PM, Ondřej Bílka wrote:
> 
> >Yes, I wrote that from head so I forgot volatile/asm barrier. One could
> >add requirement like needs to be compiled by gcc4-6+ instead pure C as
> >just using signals is not part of C standard.
> 
> GCC emulates atomics with locks on some platforms, or some lock-free
> instruction sequences may not be reentrant.  This begins to look
> like a can of worms, unfortunately.
> 
It uses only thread local variable. If they are not reentrant its
gigantic hole, you could not for example use sigaction as it could 
set errno which is thread local variable.