_Noreturn void pthread_exit(void *result)
{
pthread_t self = pthread_self();
- int n;
+ sigset_t set;
self->result = result;
/* Mark this thread dead before decrementing count */
__lock(self->killlock);
self->dead = 1;
+
+ /* Block all signals before decrementing the live thread count.
+ * This is important to ensure that dynamically allocated TLS
+ * is not under-allocated/over-committed, and possibly for other
+ * reasons as well. */
+ __block_all_sigs(&set);
+
+ /* Wait to unlock the kill lock, which governs functions like
+ * pthread_kill which target a thread id, until signals have
+ * been blocked. This precludes observation of the thread id
+ * as a live thread (with application code running in it) after
+ * the thread was reported dead by ESRCH being returned. */
__unlock(self->killlock);
- do n = libc.threads_minus_1;
- while (n && a_cas(&libc.threads_minus_1, n, n-1)!=n);
- if (!n) exit(0);
+ /* It's impossible to determine whether this is "the last thread"
+ * until performing the atomic decrement, since multiple threads
+ * could exit at the same time. For the last thread, revert the
+ * decrement and unblock signals to give the atexit handlers and
+ * stdio cleanup code a consistent state. */
+ if (a_fetch_add(&libc.threads_minus_1, -1)==0) {
+ libc.threads_minus_1 = 0;
+ __restore_sigs(&set);
+ exit(0);
+ }
if (self->detached && self->map_base) {
- if (self->detached == 2)
- __syscall(SYS_set_tid_address, 0);
- __syscall(SYS_rt_sigprocmask, SIG_BLOCK,
- SIGALL_SET, 0, _NSIG/8);
+ /* 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);
+
+ /* The following call unmaps the thread's stack mapping
+ * and then exits without touching the stack. */
__unmapself(self->map_base, self->map_size);
}
self->detached = 2;
pthread_exit(0);
}
- __syscall(SYS_rt_sigprocmask, SIG_SETMASK,
- self->sigmask, 0, _NSIG/8);
+ __restore_sigs(self->sigmask);
}
if (self->unblock_cancel)
__syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
int ret;
size_t size, guard;
struct pthread *self = pthread_self(), *new;
- unsigned char *map = 0, *stack = 0, *tsd = 0;
+ unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
unsigned flags = 0x7d8f00;
int do_sched = 0;
pthread_attr_t attr = {0};
size_t need = libc.tls_size + __pthread_tsd_size;
size = attr._a_stacksize + DEFAULT_STACK_SIZE;
stack = (void *)(attr._a_stackaddr & -16);
+ stack_limit = (void *)(attr._a_stackaddr - size);
/* Use application-provided stack for TLS only when
* it does not take more than ~12% or 2k of the
* application's stack space. */
if (map == MAP_FAILED) goto fail;
}
tsd = map + size - __pthread_tsd_size;
- if (!stack) stack = tsd - libc.tls_size;
+ if (!stack) {
+ stack = tsd - libc.tls_size;
+ stack_limit = map + guard;
+ }
}
new = __copy_tls(tsd - libc.tls_size);
new->map_base = map;
new->map_size = size;
+ new->stack = stack;
+ new->stack_size = stack - stack_limit;
new->pid = self->pid;
new->errno_ptr = &new->errno_val;
new->start = entry;
}
if (attr._a_sched) {
do_sched = new->startlock[0] = 1;
- __syscall(SYS_rt_sigprocmask, SIG_BLOCK,
- SIGALL_SET, self->sigmask, _NSIG/8);
+ __block_app_sigs(new->sigmask);
}
new->unblock_cancel = self->cancel;
new->canary = self->canary;
__release_ptc();
if (do_sched) {
- __syscall(SYS_rt_sigprocmask, SIG_SETMASK,
- new->sigmask, 0, _NSIG/8);
+ __restore_sigs(new->sigmask);
}
if (ret < 0) {