kern/sref: relax memory ordering on weak reference operations

2 files changed, 7 insertions, 4 deletions

diff --git a/kern/sref.c b/kern/sref.c
index d2eb8187..1ad9212e 100644
--- a/kern/sref.c
+++ b/kern/sref.c
@@ -248,13 +248,13 @@ sref_weakref_init(struct sref_weakref *weakref, struct sref_counter *counter)
 static void
 sref_weakref_mark_dying(struct sref_weakref *weakref)
 {
-    atomic_or(&weakref->addr, SREF_WEAKREF_DYING, ATOMIC_RELEASE);
+    atomic_or(&weakref->addr, SREF_WEAKREF_DYING, ATOMIC_RELAXED);
 }
 
 static void
 sref_weakref_clear_dying(struct sref_weakref *weakref)
 {
-    atomic_and(&weakref->addr, SREF_WEAKREF_MASK, ATOMIC_RELEASE);
+    atomic_and(&weakref->addr, SREF_WEAKREF_MASK, ATOMIC_RELAXED);
 }
 
 static int
diff --git a/kern/sref_i.h b/kern/sref_i.h
index 09dbbfa8..27f962c5 100644
--- a/kern/sref_i.h
+++ b/kern/sref_i.h
@@ -32,8 +32,11 @@
  *
  * A weak reference is a pointer to a reference counter in which the
  * least-significant bit is used to indicate whether the counter is
- * "dying", i.e. about to be destroyed. It must be accessed with atomic
- * instructions.
+ * "dying", i.e. about to be destroyed.
+ *
+ * It must be accessed with atomic instructions. There is no need to
+ * enforce memory order on access since the only data that depends on
+ * the weak reference are cpu-local deltas.
  */
 struct sref_weakref {
     uintptr_t addr;