Changeset 1871118 in mainline for kernel/generic/include/lib/refcount.h

Timestamp:

2023-02-10T22:59:11Z (2 years ago)

Author:

Jiří Zárevúcky <zarevucky.jiri@…>

Branches:

master, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

11d2c983

Parents:

daadfa6

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2023-02-10 22:53:12)

git-committer:

Jiří Zárevúcky <zarevucky.jiri@…> (2023-02-10 22:59:11)

Message:

Make thread_t reference counted

This simplifies interaction between various locks and thread
lifespan, which simplifies things. For example, threads_lock can
now simply be a mutex protecting the global it was made for, and
nothing more.

File:

• kernel/generic/include/lib/refcount.h (modified) (1 diff)

kernel/generic/include/lib/refcount.h

@@ -76 +76 @@
 }
 
+/**
+ * Try to upgrade a weak reference.
+ * Naturally, this is contingent on another form of synchronization being used
+ * to ensure that the object continues to exist while the weak reference is in
+ * use.
+ */
+static inline bool refcount_try_up(atomic_refcount_t *rc)
+{
+        int cnt = atomic_load_explicit(&rc->__cnt, memory_order_relaxed);
+
+        while (cnt >= 0) {
+                if (atomic_compare_exchange_weak_explicit(&rc->__cnt, &cnt, cnt + 1,
+                    memory_order_relaxed, memory_order_relaxed)) {
+                        return true;
+                }
+        }
+
+        return false;
+}
+
 static inline bool refcount_unique(atomic_refcount_t *rc)
 {