new attempt at making set*id() safe and robust

[musl] / src / thread / pthread_create.c

diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 0609aab..856015f 100644 (file)
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -3,8 +3,8 @@
 static void dummy_0()
 {
 }
-weak_alias(dummy_0, __rsyscall_lock);
-weak_alias(dummy_0, __rsyscall_unlock);
+weak_alias(dummy_0, __synccall_lock);
+weak_alias(dummy_0, __synccall_unlock);
 weak_alias(dummy_0, __pthread_tsd_run_dtors);
 
 #ifdef __pthread_unwind_next
@@ -22,12 +22,14 @@ void __pthread_unwind_next(struct __ptcb *cb)
                longjmp((void *)cb->__next->__jb, 1);
        }
 
-       LOCK(&self->exitlock);
-
        __pthread_tsd_run_dtors();
 
+       __lock(&self->exitlock);
+
        /* Mark this thread dead before decrementing count */
+       __lock(&self->killlock);
        self->dead = 1;
+       a_store(&self->killlock, 0);
 
        do n = libc.threads_minus_1;
        while (n && a_cas(&libc.threads_minus_1, n, n-1)!=n);
@@ -61,10 +63,10 @@ weak_alias(dummy, __pthread_tsd_size);
 int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(void *), void *arg)
 {
        int ret;
-       size_t size, guard;
+       size_t size = DEFAULT_STACK_SIZE + DEFAULT_GUARD_SIZE;
+       size_t guard = DEFAULT_GUARD_SIZE;
        struct pthread *self = pthread_self(), *new;
        unsigned char *map, *stack, *tsd;
-       const pthread_attr_t default_attr = { 0 };
 
        if (!self) return ENOSYS;
        if (!libc.threaded) {
@@ -72,9 +74,10 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
                libc.threaded = 1;
        }
 
-       if (!attr) attr = &default_attr;
-       guard = ROUND(attr->_a_guardsize + DEFAULT_GUARD_SIZE);
-       size = guard + ROUND(attr->_a_stacksize + DEFAULT_STACK_SIZE);
+       if (attr) {
+               guard = ROUND(attr->_a_guardsize + DEFAULT_GUARD_SIZE);
+               size = guard + ROUND(attr->_a_stacksize + DEFAULT_STACK_SIZE);
+       }
        size += __pthread_tsd_size;
        map = mmap(0, size, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANON, -1, 0);
        if (!map) return EAGAIN;
@@ -90,19 +93,18 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
        new->start_arg = arg;
        new->self = new;
        new->tsd = (void *)tsd;
-       new->detached = attr->_a_detach;
-       new->attr = *attr;
+       if (attr) new->detached = attr->_a_detach;
        new->unblock_cancel = self->cancel;
        memcpy(new->tlsdesc, self->tlsdesc, sizeof new->tlsdesc);
        new->tlsdesc[1] = (uintptr_t)new;
        stack = (void *)((uintptr_t)new-1 & ~(uintptr_t)15);
 
-       __rsyscall_lock();
+       __synccall_lock();
 
        a_inc(&libc.threads_minus_1);
        ret = __uniclone(stack, start, new);
 
-       __rsyscall_unlock();
+       __synccall_unlock();
 
        if (ret < 0) {
                a_dec(&libc.threads_minus_1);