Use atomics for system_working global

Although it almost certainly works in this case, volatile is best not
used for multi-threaded code. Using atomics instead avoids warnings from
TSan.

This also simplifies some logic, as system_working was previously only
ever assigned to 1, so --system_working <= 0 should always return true
(unless it underflowed).

1 files changed, 1 insertions, 1 deletions

diff --git a/thread.c b/thread.c
index ab28b0debc..0494524510 100644
--- a/thread.c
+++ b/thread.c
@@ -148,7 +148,7 @@ static int hrtime_update_expire(rb_hrtime_t *, const rb_hrtime_t);
 NORETURN(static void async_bug_fd(const char *mesg, int errno_arg, int fd));
 MAYBE_UNUSED(static int consume_communication_pipe(int fd));
 
-static volatile int system_working = 1;
+static rb_atomic_t system_working = 1;
 static rb_internal_thread_specific_key_t specific_key_count;
 
 /********************************************************************************/