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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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32
libc/thread/pthread_atfork.c
View file

@ -20,6 +20,7 @@
#include "libc/errno.h"
#include "libc/intrin/atomic.h"
#include "libc/intrin/kmalloc.h"
#include "libc/mem/mem.h"
#include "libc/runtime/memtrack.internal.h"
#include "libc/str/str.h"
#include "libc/thread/posixthread.internal.h"
@ -34,6 +35,14 @@ static struct AtForks {
} * list;
} _atforks;
static void _pthread_purge(void) {
nsync_dll_element_ *e;
while ((e = nsync_dll_first_(_pthread_list))) {
_pthread_list = nsync_dll_remove_(_pthread_list, e);
_pthread_free(e->container);
}
}
static void _pthread_onfork(int i) {
struct AtFork *a;
struct PosixThread *pt;
@ -44,17 +53,11 @@ static void _pthread_onfork(int i) {
_atforks.list = a;
}
if (i) pthread_spin_unlock(&_atforks.lock);
if (i == 2) {
_pthread_zombies_purge();
if (__tls_enabled) {
pt = (struct PosixThread *)__get_tls()->tib_pthread;
pt->flags |= PT_MAINTHREAD;
}
}
}
void _pthread_onfork_prepare(void) {
_pthread_onfork(0);
pthread_spin_lock(&_pthread_lock);
__kmalloc_lock();
__mmi_lock();
}
@ -62,6 +65,7 @@ void _pthread_onfork_prepare(void) {
void _pthread_onfork_parent(void) {
__mmi_unlock();
__kmalloc_unlock();
pthread_spin_unlock(&_pthread_lock);
_pthread_onfork(1);
}
@ -72,12 +76,26 @@ void _pthread_onfork_child(void) {
extern pthread_mutex_t __mmi_lock_obj;
tib = __get_tls();
pt = (struct PosixThread *)tib->tib_pthread;
// let's choose to let the new process live.
// even though it's unclear what to do with this kind of race.
atomic_store_explicit(&pt->cancelled, false, memory_order_relaxed);
// wipe core runtime locks
pthread_mutexattr_init(&attr);
pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
pthread_mutex_init(&__mmi_lock_obj, &attr);
pthread_spin_init(&_pthread_lock, 0);
__kmalloc_unlock();
// call user-supplied forked child callbacks
_pthread_onfork(2);
// delete other threads that existed before forking
// this must come after onfork, since it calls free
_pthread_list = nsync_dll_remove_(_pthread_list, &pt->list);
_pthread_purge();
_pthread_list = nsync_dll_make_first_in_list_(_pthread_list, &pt->list);
}
int _pthread_atfork(atfork_f prepare, atfork_f parent, atfork_f child) {