Data race within write intrinsic with output into a character variable

[mscfd <mscfd@gmx.net>]

Sorry for the noise, but line breaks and subject
were somehow missing...

> which version of gfortran, and which operating system?
I have seen this on two different Linux distros on x86
with a recently compiled version, but also some
time ago with an older gfortran 10 version.

Using helgrind on a simple omp do loop with write to
a character variable, I get some possible data races
in libgfortran/io/unit.c. There global array newunits is
allocated and possibly reallocated in
"newunit_alloc". According to the lock outputs from
helgrind I see that this routine is called even if
output is into a character variable. Routine
"newunit_alloc" uses a lock to avoid having several
threads all over the place. But newunit_free also
writes to newunits array. And this routine does not
obtain a lock itself (see comment above newunit_free
in unit.c) So in theory it can happen that newunit_alloc
reallocated newunits, and newunit_free writes to it just
at this time. As I also use 18 threads the initial size of 16
does not suffice and reallocation does probably
indeed happen.
Also acces to newunit_lwi is not protected as well
(and complained about by helgrind).
 
Could it be that the corresponding write routine in
transfer.c which calls newunit_free does not obtain
the necessary lock. I cannot find it (which does not
count for much).
 
Any thoughts?
Martin