Changeset 1871118 in mainline for kernel/generic/include

Timestamp:

2023-02-10T22:59:11Z (3 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.

Location:

kernel/generic/include

Files:

• lib/refcount.h (modified) (1 diff)
• proc/thread.h (modified) (6 diffs)
• synch/waitq.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)
 {

kernel/generic/include/proc/thread.h

@@ -70 +70 @@
 /** Thread structure. There is one per thread. */
 typedef struct thread {
+        atomic_refcount_t refcount;
+
         link_t rq_link;  /**< Run queue link. */
         link_t wq_link;  /**< Wait queue link. */
@@ -77 +79 @@
         odlink_t lthreads;
 
+        /**
+         * If true, the thread is terminating.
+         * It will not go to sleep in interruptible synchronization functions
+         * and will call thread_exit() before returning to userspace.
+         */
+        volatile bool interrupted;
+
+        /** Waitq for thread_join_timeout(). */
+        waitq_t join_wq;
+
         /** Lock protecting thread structure.
          *
-         * Protects the whole thread structure except list links above.
+         * Protects the whole thread structure except fields listed above.
          */
         IRQ_SPINLOCK_DECLARE(lock);
@@ -133 +145 @@
          */
         bool in_copy_to_uspace;
-
-        /**
-         * If true, the thread will not go to sleep at all and will call
-         * thread_exit() before returning to userspace.
-         */
-        bool interrupted;
-
-        /** If true, thread_join_timeout() cannot be used on this thread. */
-        bool detached;
-        /** Waitq for thread_join_timeout(). */
-        waitq_t join_wq;
-        /** Link used in the joiner_head list. */
-        link_t joiner_link;
 
 #ifdef CONFIG_FPU
@@ -219 +218 @@
 extern void thread_interrupt(thread_t *, bool);
 
+static inline thread_t *thread_ref(thread_t *thread)
+{
+        refcount_up(&thread->refcount);
+        return thread;
+}
+
+static inline thread_t *thread_try_ref(thread_t *thread)
+{
+        if (refcount_try_up(&thread->refcount))
+                return thread;
+        else
+                return NULL;
+}
+
+extern void thread_put(thread_t *);
+
 #ifndef thread_create_arch
 extern errno_t thread_create_arch(thread_t *, thread_flags_t);
@@ -236 +251 @@
 extern errno_t thread_join(thread_t *);
 extern errno_t thread_join_timeout(thread_t *, uint32_t, unsigned int);
-extern void thread_detach(thread_t *);
 
 extern void thread_print_list(bool);
-extern void thread_destroy(thread_t *, bool);
 extern thread_t *thread_find_by_id(thread_id_t);
 extern size_t thread_count(void);
@@ -245 +258 @@
 extern thread_t *thread_next(thread_t *);
 extern void thread_update_accounting(bool);
-extern bool thread_exists(thread_t *);
+extern thread_t *thread_try_get(thread_t *);
 
 extern void thread_migration_disable(void);

kernel/generic/include/synch/waitq.h

@@ -43 +43 @@
 typedef enum {
         WAKEUP_FIRST = 0,
-        WAKEUP_ALL
+        WAKEUP_ALL,
+        WAKEUP_CLOSE,
 } wakeup_mode_t;