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lib/pthread: Fix create/join race in thread lifecycle #57721

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lib/pthread: Fix create/join race in thread lifecycle #57721

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c897766
kernel: Add z_thread_wake_joiners() utility
andyross May 10, 2023
48596a1
lib/pthread: Fix create/join race in thread lifecycle
andyross May 9, 2023
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1 change: 1 addition & 0 deletions kernel/include/ksched.h
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Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,7 @@ void z_ready_thread(struct k_thread *thread);
void z_requeue_current(struct k_thread *curr);
struct k_thread *z_swap_next_thread(void);
void z_thread_abort(struct k_thread *thread);
void z_thread_wake_joiners(struct k_thread *thread);

static inline void z_pend_curr_unlocked(_wait_q_t *wait_q, k_timeout_t timeout)
{
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7 changes: 7 additions & 0 deletions kernel/sched.c
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Expand Up @@ -1729,6 +1729,13 @@ static void end_thread(struct k_thread *thread)
}
}

void z_thread_wake_joiners(struct k_thread *thread)
{
LOCKED(&sched_spinlock) {
unpend_all(&thread->join_queue);
}
}

void z_thread_abort(struct k_thread *thread)
{
k_spinlock_key_t key = k_spin_lock(&sched_spinlock);
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1 change: 0 additions & 1 deletion lib/posix/posix_internal.h
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Expand Up @@ -54,7 +54,6 @@ struct posix_thread {
/* Pthread State */
enum pthread_state state;
pthread_mutex_t state_lock;
pthread_cond_t state_cond;
};

typedef struct pthread_key_obj {
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21 changes: 7 additions & 14 deletions lib/posix/pthread.c
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Original file line number Diff line number Diff line change
Expand Up @@ -159,7 +159,6 @@ int pthread_create(pthread_t *newthread, const pthread_attr_t *_attr,
k_spinlock_key_t key;
uint32_t pthread_num;
k_spinlock_key_t cancel_key;
pthread_condattr_t cond_attr;
struct posix_thread *thread;
const struct pthread_attr *attr = (const struct pthread_attr *)_attr;

Expand Down Expand Up @@ -207,7 +206,6 @@ int pthread_create(pthread_t *newthread, const pthread_attr_t *_attr,
thread->state = attr->detachstate;
pthread_mutex_unlock(&thread->state_lock);

pthread_cond_init(&thread->state_cond, &cond_attr);
sys_slist_init(&thread->key_list);

*newthread = pthread_num;
Expand Down Expand Up @@ -274,7 +272,6 @@ int pthread_cancel(pthread_t pthread)
} else {
thread->retval = PTHREAD_CANCELED;
thread->state = PTHREAD_EXITED;
pthread_cond_broadcast(&thread->state_cond);
}
pthread_mutex_unlock(&thread->state_lock);

Expand Down Expand Up @@ -395,7 +392,6 @@ void pthread_exit(void *retval)
if (self->state == PTHREAD_JOINABLE) {
self->state = PTHREAD_EXITED;
self->retval = retval;
pthread_cond_broadcast(&self->state_cond);
} else {
self->state = PTHREAD_TERMINATED;
}
Expand All @@ -413,8 +409,6 @@ void pthread_exit(void *retval)
pthread_mutex_unlock(&self->state_lock);
pthread_mutex_destroy(&self->state_lock);

pthread_cond_destroy(&self->state_cond);

k_thread_abort((k_tid_t)self);
}

Expand All @@ -436,12 +430,14 @@ int pthread_join(pthread_t thread, void **status)
return ESRCH;
}

pthread_mutex_lock(&pthread->state_lock);

if (pthread->state == PTHREAD_JOINABLE) {
pthread_cond_wait(&pthread->state_cond, &pthread->state_lock);
if (pthread->state == PTHREAD_DETACHED) {
return EINVAL;
}

k_thread_join(&pthread->thread, K_FOREVER);

pthread_mutex_lock(&pthread->state_lock);

if (pthread->state == PTHREAD_EXITED) {
if (status != NULL) {
*status = pthread->retval;
Expand Down Expand Up @@ -479,10 +475,7 @@ int pthread_detach(pthread_t thread)
switch (pthread->state) {
case PTHREAD_JOINABLE:
pthread->state = PTHREAD_DETACHED;
/* Broadcast the condition.
* This will make threads waiting to join this thread continue.
*/
pthread_cond_broadcast(&pthread->state_cond);
z_thread_wake_joiners(&pthread->thread);
break;
case PTHREAD_EXITED:
pthread->state = PTHREAD_TERMINATED;
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