race condition fix: block all signals before decrementing thread count

[musl] / src / thread / pthread_create.c

diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 72d7acb..c73c521 100644 (file)
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -10,9 +10,6 @@ void __pthread_unwind_next(struct __ptcb *cb)
        self = pthread_self();
        if (self->cancel) self->result = PTHREAD_CANCELLED;
 
-       if (!a_fetch_add(&libc.threads_minus_1, -1))
-               exit(0);
-
        LOCK(&self->exitlock);
 
        not_finished = self->tsd_used;
@@ -28,6 +25,11 @@ void __pthread_unwind_next(struct __ptcb *cb)
                }
        }
 
+       syscall4(__NR_sigprocmask, SIG_BLOCK, (long)(uint64_t[1]){-1}, 0, 8);
+
+       if (!a_fetch_add(&libc.threads_minus_1, -1))
+               exit(0);
+
        if (self->detached && self->map_base)
                __unmapself(self->map_base, self->map_size);
 
@@ -152,8 +154,7 @@ static int start(void *p)
        return 0;
 }
 
-#define CLONE_MAGIC 0x7d0f00
-int __clone(int (*)(void *), void *, int, void *, pid_t *, void *, pid_t *);
+int __uniclone(void *, int (*)(), void *);
 
 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
 
@@ -174,8 +175,8 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
        if (!init && ++init) init_threads();
 
        if (!attr) attr = &default_attr;
-       guard = ROUND(attr->__guardsize + DEFAULT_GUARD_SIZE);
-       size = guard + ROUND(attr->__stacksize + DEFAULT_STACK_SIZE);
+       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;
@@ -191,7 +192,7 @@ 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->__detach;
+       new->detached = attr->_a_detach;
        new->attr = *attr;
        memcpy(new->tlsdesc, self->tlsdesc, sizeof new->tlsdesc);
        new->tlsdesc[1] = (uintptr_t)new;
@@ -203,8 +204,7 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
        while (rs.lock) __wait(&rs.lock, 0, 1, 1);
 
        a_inc(&libc.threads_minus_1);
-       ret = __clone(start, stack, CLONE_MAGIC, new,
-               &new->tid, &new->tlsdesc, &new->tid);
+       ret = __uniclone(stack, start, new);
 
        a_dec(&rs.blocks);
        if (rs.lock) __wake(&rs.blocks, 1, 1);
@@ -212,7 +212,7 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
        if (ret < 0) {
                a_dec(&libc.threads_minus_1);
                munmap(map, size);
-               return -ret;
+               return EAGAIN;
        }
        *res = new;
        return 0;