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-rw-r--r--src/env/__init_tls.c4
-rw-r--r--src/internal/pthread_impl.h12
-rw-r--r--src/thread/pthread_create.c21
-rw-r--r--src/thread/pthread_detach.c7
-rw-r--r--src/thread/pthread_getattr_np.c2
-rw-r--r--src/thread/pthread_join.c11
6 files changed, 33 insertions, 24 deletions
diff --git a/src/env/__init_tls.c b/src/env/__init_tls.c
index 80044960..1c5d98a0 100644
--- a/src/env/__init_tls.c
+++ b/src/env/__init_tls.c
@@ -15,8 +15,8 @@ int __init_tp(void *p)
int r = __set_thread_area(TP_ADJ(p));
if (r < 0) return -1;
if (!r) libc.can_do_threads = 1;
- td->join_futex = -1;
- td->tid = __syscall(SYS_set_tid_address, &td->join_futex);
+ td->detach_state = DT_JOINABLE;
+ td->tid = __syscall(SYS_set_tid_address, &td->detach_state);
td->locale = &libc.global_locale;
td->robust_list.head = &td->robust_list.head;
return 0;
diff --git a/src/internal/pthread_impl.h b/src/internal/pthread_impl.h
index 3b4ad94d..0a65fa37 100644
--- a/src/internal/pthread_impl.h
+++ b/src/internal/pthread_impl.h
@@ -24,7 +24,7 @@ struct pthread {
/* Part 2 -- implementation details, non-ABI. */
int tsd_used, errno_val;
volatile int cancel, canceldisable, cancelasync;
- int detached;
+ volatile int detach_state;
unsigned char *map_base;
size_t map_size;
void *stack;
@@ -42,9 +42,7 @@ struct pthread {
int unblock_cancel;
volatile int timer_id;
locale_t locale;
- volatile int join_futex;
volatile int killlock[1];
- volatile int exitlock[1];
volatile int startlock[2];
unsigned long sigmask[_NSIG/8/sizeof(long)];
char *dlerror_buf;
@@ -58,6 +56,14 @@ struct pthread {
void **dtv_copy;
};
+enum {
+ DT_EXITED = 0,
+ DT_EXITING,
+ DT_JOINABLE,
+ DT_DETACHED,
+ DT_DYNAMIC,
+};
+
struct __timer {
int timerid;
pthread_t thread;
diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index a86b5e1b..e07d29e3 100644
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -37,8 +37,6 @@ _Noreturn void __pthread_exit(void *result)
__pthread_tsd_run_dtors();
- LOCK(self->exitlock);
-
/* Access to target the exiting thread with syscalls that use
* its kernel tid is controlled by killlock. For detached threads,
* any use past this point would have undefined behavior, but for
@@ -85,15 +83,19 @@ _Noreturn void __pthread_exit(void *result)
__do_orphaned_stdio_locks();
__dl_thread_cleanup();
- if (self->detached && self->map_base) {
+ /* This atomic potentially competes with a concurrent pthread_detach
+ * call; the loser is responsible for freeing thread resources. */
+ int state = a_cas(&self->detach_state, DT_JOINABLE, DT_EXITING);
+
+ if (state>=DT_DETACHED && self->map_base) {
/* Detached threads must avoid the kernel clear_child_tid
* feature, since the virtual address will have been
* unmapped and possibly already reused by a new mapping
* at the time the kernel would perform the write. In
* the case of threads that started out detached, the
* initial clone flags are correct, but if the thread was
- * detached later (== 2), we need to clear it here. */
- if (self->detached == 2) __syscall(SYS_set_tid_address, 0);
+ * detached later, we need to clear it here. */
+ if (state == DT_DYNAMIC) __syscall(SYS_set_tid_address, 0);
/* Robust list will no longer be valid, and was already
* processed above, so unregister it with the kernel. */
@@ -141,7 +143,7 @@ static int start(void *p)
if (self->startlock[0]) {
__wait(self->startlock, 0, 1, 1);
if (self->startlock[0] == 2) {
- self->detached = 2;
+ self->detach_state = DT_DYNAMIC;
pthread_exit(0);
}
__restore_sigs(self->sigmask);
@@ -274,8 +276,10 @@ int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict att
new->tsd = (void *)tsd;
new->locale = &libc.global_locale;
if (attr._a_detach) {
- new->detached = 1;
+ new->detach_state = DT_DETACHED;
flags -= CLONE_CHILD_CLEARTID;
+ } else {
+ new->detach_state = DT_JOINABLE;
}
if (attr._a_sched) {
do_sched = new->startlock[0] = 1;
@@ -284,10 +288,9 @@ int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict att
new->robust_list.head = &new->robust_list.head;
new->unblock_cancel = self->cancel;
new->CANARY = self->CANARY;
- new->join_futex = -1;
a_inc(&libc.threads_minus_1);
- ret = __clone((c11 ? start_c11 : start), stack, flags, new, &new->tid, TP_ADJ(new), &new->join_futex);
+ ret = __clone((c11 ? start_c11 : start), stack, flags, new, &new->tid, TP_ADJ(new), &new->detach_state);
__release_ptc();
diff --git a/src/thread/pthread_detach.c b/src/thread/pthread_detach.c
index 692bbaf9..9cee7a89 100644
--- a/src/thread/pthread_detach.c
+++ b/src/thread/pthread_detach.c
@@ -5,11 +5,10 @@ int __pthread_join(pthread_t, void **);
static int __pthread_detach(pthread_t t)
{
- /* Cannot detach a thread that's already exiting */
- if (a_cas(t->exitlock, 0, INT_MIN + 1))
+ /* If the cas fails, detach state is either already-detached
+ * or exiting/exited, and pthread_join will trap or cleanup. */
+ if (a_cas(&t->detach_state, DT_JOINABLE, DT_DYNAMIC) != DT_JOINABLE)
return __pthread_join(t, 0);
- t->detached = 2;
- UNLOCK(t->exitlock);
return 0;
}
diff --git a/src/thread/pthread_getattr_np.c b/src/thread/pthread_getattr_np.c
index 29a209bd..2881831f 100644
--- a/src/thread/pthread_getattr_np.c
+++ b/src/thread/pthread_getattr_np.c
@@ -6,7 +6,7 @@
int pthread_getattr_np(pthread_t t, pthread_attr_t *a)
{
*a = (pthread_attr_t){0};
- a->_a_detach = !!t->detached;
+ a->_a_detach = t->detach_state>=DT_DETACHED;
a->_a_guardsize = t->guard_size;
if (t->stack) {
a->_a_stackaddr = (uintptr_t)t->stack;
diff --git a/src/thread/pthread_join.c b/src/thread/pthread_join.c
index 67eaf9d8..18264da6 100644
--- a/src/thread/pthread_join.c
+++ b/src/thread/pthread_join.c
@@ -7,13 +7,14 @@ int __pthread_setcancelstate(int, int *);
int __pthread_timedjoin_np(pthread_t t, void **res, const struct timespec *at)
{
- int tmp, cs, r = 0;
+ int state, cs, r = 0;
__pthread_testcancel();
__pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
if (cs == PTHREAD_CANCEL_ENABLE) __pthread_setcancelstate(cs, 0);
- if (t->detached) a_crash();
- while ((tmp = t->join_futex) && r != ETIMEDOUT && r != EINVAL)
- r = __timedwait_cp(&t->join_futex, tmp, CLOCK_REALTIME, at, 0);
+ while ((state = t->detach_state) && r != ETIMEDOUT && r != EINVAL) {
+ if (state >= DT_DETACHED) a_crash();
+ r = __timedwait_cp(&t->detach_state, state, CLOCK_REALTIME, at, 0);
+ }
__pthread_setcancelstate(cs, 0);
if (r == ETIMEDOUT || r == EINVAL) return r;
a_barrier();
@@ -29,7 +30,7 @@ int __pthread_join(pthread_t t, void **res)
int __pthread_tryjoin_np(pthread_t t, void **res)
{
- return t->join_futex ? EBUSY : __pthread_join(t, res);
+ return t->detach_state==DT_JOINABLE ? EBUSY : __pthread_join(t, res);
}
weak_alias(__pthread_tryjoin_np, pthread_tryjoin_np);
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-02-01 19:23:54 +0000