Changeset 1871118 in mainline for kernel/generic/src/proc/scheduler.c

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/src/proc/scheduler.c (modified) (3 diffs)

kernel/generic/src/proc/scheduler.c

@@ -389 +389 @@
 void scheduler_separated_stack(void)
 {
-        DEADLOCK_PROBE_INIT(p_joinwq);
         task_t *old_task = TASK;
         as_t *old_as = AS;
@@ -419 +418 @@
 
                 case Exiting:
-                repeat:
-                        if (THREAD->detached) {
-                                thread_destroy(THREAD, false);
-                        } else {
-                                /*
-                                 * The thread structure is kept allocated until
-                                 * somebody calls thread_detach() on it.
-                                 */
-                                if (!irq_spinlock_trylock(&THREAD->join_wq.lock)) {
-                                        /*
-                                         * Avoid deadlock.
-                                         */
-                                        irq_spinlock_unlock(&THREAD->lock, false);
-                                        delay(HZ);
-                                        irq_spinlock_lock(&THREAD->lock, false);
-                                        DEADLOCK_PROBE(p_joinwq,
-                                            DEADLOCK_THRESHOLD);
-                                        goto repeat;
-                                }
-                                _waitq_wakeup_unsafe(&THREAD->join_wq,
-                                    WAKEUP_FIRST);
-                                irq_spinlock_unlock(&THREAD->join_wq.lock, false);
-
-                                THREAD->state = Lingering;
-                                irq_spinlock_unlock(&THREAD->lock, false);
-                        }
+                        irq_spinlock_unlock(&THREAD->lock, false);
+                        waitq_wakeup(&THREAD->join_wq, WAKEUP_CLOSE);
+
+                        /*
+                         * Release the reference CPU has for the thread.
+                         * If there are no other references (e.g. threads calling join),
+                         * the thread structure is deallocated.
+                         */
+                        thread_put(THREAD);
                         break;
 
@@ -556 +538 @@
         size_t average;
         size_t rdy;
-
-        /*
-         * Detach kcpulb as nobody will call thread_join_timeout() on it.
-         */
-        thread_detach(THREAD);
 
 loop: