[PATCH] Disable single thread optimization for open_memstream

[Carlos O'Donell]

On 07/14/2017 09:01 AM, Szabolcs Nagy wrote:
> Single thread optimization is valid if at thread creation time the
> optimization can be disabled.  This is in principle true for all
> stream objects that user code can access (and thus needs locking),
> using the same internal list as fflush(0) uses.  However in glibc
> open_memstream is not on that list (BZ 21735) so the optimization
> has to be disabled.
> 
> OK with the test?
> 
> 2017-07-14  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> 	    Florian Weimer  <fweimer@redhat.com>
> 
> 	* libio/memstream.c (__open_memstream): Set _IO_FLAGS2_NEED_LOCK.
> 	* libio/wmemstream.c (open_wmemstream): Likewise.
> 	* nptl/tst-memstream.c: New.
> 

OK to checkin if you add a pargraph comment to tst-memstream.c
explaining the test invariants, expectations, and exactly what
is being tested and why.

-- 
Cheers,
Carlos.