QReadWriteLocker: Fix race in unlock

An Acquire barrier in QReadWriteLocker::unlock was missing to synchronize
with the testAndSetOrdered on d_ptr in the lock functions.

The race is between the write of d->writerCount in tryLockForWrite,
and the read in unlock. The acquire on d->mutex is not enough because
it is not on the same object. While that race could be fixed by taking
the newly-allocate()ed d's mutex before publishing it with testAndSet,
there's another race, on 'recursive', between a newly-minted Private*
with recursive == false in tryLockForWrite(), and the read of 'recursive'
in unlock().

Task-number: QTBUG-58917
Change-Id: I10ba36573c0e57468d11e9b77d85045711feaea1
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

0 files changed, 0 insertions, 0 deletions