diff options
| -rw-r--r-- | kern/thread.c | 25 | ||||
| -rw-r--r-- | kern/thread.h | 2 | ||||
| -rw-r--r-- | kern/thread_i.h | 17 |
3 files changed, 23 insertions, 21 deletions
diff --git a/kern/thread.c b/kern/thread.c index 78c75bad..17586eaf 100644 --- a/kern/thread.c +++ b/kern/thread.c @@ -1826,7 +1826,7 @@ thread_init(struct thread *thread, void *stack, memset(thread->tsd, 0, sizeof(thread->tsd)); thread->join_waiter = NULL; spinlock_init(&thread->join_lock); - thread->exiting = false; + thread->terminating = false; thread->task = task; thread->stack = stack; strlcpy(thread->name, attr->name, sizeof(thread->name)); @@ -1953,7 +1953,7 @@ thread_free_stack(void *stack) #endif /* X15_THREAD_STACK_GUARD */ -void +static void thread_destroy(struct thread *thread) { assert(thread != thread_self()); @@ -1984,7 +1984,7 @@ thread_join_common(struct thread *thread) assert(!thread->join_waiter); thread->join_waiter = self; - while (!thread->exiting) { + while (!thread->terminating) { thread_sleep(&thread->join_lock, thread, "exit"); } @@ -1996,7 +1996,15 @@ thread_join_common(struct thread *thread) thread_unlock_runq(runq, flags); } while (state != THREAD_DEAD); - thread_unref(thread); + thread_destroy(thread); +} + +void thread_terminate(struct thread *thread) +{ + spinlock_lock(&thread->join_lock); + thread->terminating = true; + thread_wakeup(thread->join_waiter); + spinlock_unlock(&thread->join_lock); } static void @@ -2391,16 +2399,9 @@ thread_exit(void) work_schedule(&zombie.work, 0); } - /* - * Disable preemption before waking up since step 2 of the termination - * protocol involves actively polling the thread state. - */ thread_preempt_disable(); - spinlock_lock(&thread->join_lock); - thread->exiting = true; - thread_wakeup(thread->join_waiter); - spinlock_unlock(&thread->join_lock); + thread_unref(thread); runq = thread_runq_local(); spinlock_lock_intr_save(&runq->lock, &flags); diff --git a/kern/thread.h b/kern/thread.h index 43a98e87..f565c155 100644 --- a/kern/thread.h +++ b/kern/thread.h @@ -291,7 +291,7 @@ thread_unref(struct thread *thread) assert(nr_refs != 0); if (nr_refs == 1) { - thread_destroy(thread); + thread_terminate(thread); } } diff --git a/kern/thread_i.h b/kern/thread_i.h index 7cbd3c72..cd349771 100644 --- a/kern/thread_i.h +++ b/kern/thread_i.h @@ -173,16 +173,17 @@ struct thread { * Members related to termination. * * The termination protocol is made of two steps : - * 1/ The thread exits, thereby reporting that it is exiting while - * holding the join lock. This includes waking up any thread - * currently joining. - * 2/ The thread sets its state to dead and calls the scheduler. - * The join operation polls the state, and releases a reference - * when it sees the dead state. + * 1/ The thread exits, thereby releasing its self reference, and + * sets its state to dead before calling the scheduler. + * 2/ Another thread must either already be joining, or join later. + * When the thread reference counter drops to zero, the terminating + * flag is set, and the joining thread is awaken, if any. After that, + * the join operation polls the state until it sees the target thread + * as dead, and then releases its resources. */ struct thread *join_waiter; /* (j) */ struct spinlock join_lock; - bool exiting; /* (j) */ + bool terminating; /* (j) */ struct task *task; /* (T) */ struct list task_node; /* (T) */ @@ -192,7 +193,7 @@ struct thread { #define THREAD_ATTR_DETACHED 0x1 -void thread_destroy(struct thread *thread); +void thread_terminate(struct thread *thread); /* * Flag access functions. |