https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106183
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> --- Created attachment 53394 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53394&action=edit Proposed patch: Unblock atomic wait on non-futex platforms When using a mutex and condition variable, the notifying thread needs to increment _M_ver while holding the mutex lock, and the waiting thread needs to re-check after locking the mutex. This avoids a missed notification as described in the PR. By moving the increment of _M_ver to the base _M_notify we can make the use of the mutex local to the use of the condition variable, and simplify the code a little. We can use a relaxed store because the mutex already provides sequential consistency. Also we don't need to check whether __addr == &_M_ver because we know that's always true for platforms that use a condition variable, and so we also know that we always need to use notify_all() not notify_one().
