bug#61058: [PATCH] Fix asymetric mutex locking when joining thread.

[Olivier Dion]

From: Olivier Dion <olivier-dion@proton.me>

If `join-thread' timeout, the thread mutex is not unlocked,
resulting in deadlock to the next call to it or deadlock of the
thread itself when it terminates.

Thus, always unlock the mutex.

Fix: #55356

* module/ice-9/threads.scm (join-thread): Always unlock thread mutex.
---
 module/ice-9/threads.scm | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/module/ice-9/threads.scm b/module/ice-9/threads.scm
index c42bd266f..962caee70 100644
--- a/module/ice-9/threads.scm
+++ b/module/ice-9/threads.scm
@@ -197,7 +197,9 @@ terminates, unless the target @var{thread} has already 
terminated."
              (wait-condition-variable cv mutex timeout)
              (wait-condition-variable cv mutex))
          (lp))
-        (else timeoutval))))))
+        (else
+         (unlock-mutex mutex)
+         timeoutval))))))
 
 (define* (try-mutex mutex)
   "Try to lock @var{mutex}.  If the mutex is already locked, return
-- 
2.39.1