master: Use a barrier instead of CAS in mutex-owner

The branch "master" has been updated in SBCL:
       via  44c6928308e64daff70f67863c8d232e5e21bb85 (commit)
      from  4acf4acdbdabc66630be96f3a88d9c339a5f4ec4 (commit)

- Log -----------------------------------------------------------------
commit 44c6928308e64daff70f67863c8d232e5e21bb85
Author: Douglas Katzman <[email protected]>
Date:   Thu Apr 30 12:17:49 2026 -0400

    Use a barrier instead of CAS in mutex-owner
    
    Rev 5234b3ca in 20009 added a CAS because BARRIER did not exist.
    BARRIER was invented later, rev 65b5ab7e in 2010.
    
    And remove inline which has no reason for being
---
 src/code/thread.lisp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/code/thread.lisp b/src/code/thread.lisp
index a80b669ce..6581c21ab 100644
--- a/src/code/thread.lisp
+++ b/src/code/thread.lisp
@@ -57,7 +57,6 @@ stale value, use MUTEX-OWNER instead."
   ;; sufficient.
   (= (mutex-%owner mutex) (current-vmthread-id)))
 
-(declaim (inline mutex-owner))
 (defun mutex-owner (mutex)
   "Current owner of the mutex, NIL if the mutex is free. Naturally,
 this is racy by design (another thread may acquire the mutex after
@@ -65,7 +64,8 @@ this function returns), it is intended for informative purposes. For
 testing whether the current thread is holding a mutex see
 HOLDING-MUTEX-P."
   ;; Make sure to get the current value.
-  (let ((vmthread (sb-ext:compare-and-swap (mutex-%owner mutex) 0 0)))
+  (barrier (:read))
+  (let ((vmthread (mutex-%owner mutex)))
     (cond ((= vmthread (current-vmthread-id)) *current-thread*)
           ((= vmthread 0) nil)
           (t (mutex-owner-lookup vmthread)))))

-----------------------------------------------------------------------


hooks/post-receive
-- 
SBCL