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Make detached threads work better

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This change adds a double linked list of threads, so that pthread_exit()
will know when it should call exit() from an orphaned child. This change
also improves ftrace and strace logging.
This commit is contained in:
Justine Tunney 2022-11-09 03:58:57 -08:00
parent b74d8c1acd
commit cee6871710
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GPG key ID: BE714B4575D6E328
37 changed files with 638 additions and 314 deletions
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42
libc/thread/pthread_join.c
View file

@ -16,21 +16,29 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/errno.h"
#include "libc/intrin/atomic.h"
#include "libc/thread/posixthread.internal.h"
#include "libc/thread/thread.h"
#include "libc/thread/tls.h"
#include "libc/thread/wait0.internal.h"
/**
* Waits for thread to terminate.
*
* Multiple threads joining the same thread is undefined behavior. If a
* deferred or masked cancellation happens to the calling thread either
* before or during the waiting process then the target thread will not
* be joined. Calling pthread_join() on a non-joinable thread, e.g. one
* that's been detached, is undefined behavior. If a thread attempts to
* join itself, then the behavior is undefined.
*
* @param value_ptr if non-null will receive pthread_exit() argument
* if the thread called pthread_exit(), or `PTHREAD_CANCELED` if
* pthread_cancel() destroyed the thread instead
* @return 0 on success, or errno on error
* @raise ECANCELED if calling thread was cancelled in masked mode
* @raise EDEADLK if `thread` is the current thread
* @raise EINVAL if `thread` is detached
* @cancellationpoint
* @returnserrno
* @threadsafe
@ -38,20 +46,22 @@
errno_t pthread_join(pthread_t thread, void **value_ptr) {
errno_t rc;
struct PosixThread *pt;
if (thread == __get_tls()->tib_pthread) {
return EDEADLK;
enum PosixThreadStatus status;
pt = (struct PosixThread *)thread;
status = atomic_load_explicit(&pt->status, memory_order_acquire);
// "The behavior is undefined if the value specified by the thread
// argument to pthread_join() does not refer to a joinable thread."
// ──Quoth POSIX.1-2017
_unassert(status == kPosixThreadJoinable || status == kPosixThreadTerminated);
if (!(rc = _wait0(&pt->tib->tib_tid))) {
pthread_spin_lock(&_pthread_lock);
_pthread_list = nsync_dll_remove_(_pthread_list, &pt->list);
pthread_spin_unlock(&_pthread_lock);
if (value_ptr) {
*value_ptr = pt->rc;
}
_pthread_free(pt);
pthread_decimate_np();
}
if (!(pt = (struct PosixThread *)thread) || //
pt->status == kPosixThreadZombie || //
pt->status == kPosixThreadDetached) {
return EINVAL;
}
if ((rc = _pthread_wait(pt))) {
return rc;
}
if (value_ptr) {
*value_ptr = pt->rc;
}
_pthread_free(pt);
return 0;
}