+#define _GNU_SOURCE
#include "pthread_impl.h"
#include "stdio_impl.h"
+#include "libc.h"
#include <sys/mman.h>
static void dummy_0()
_Noreturn void pthread_exit(void *result)
{
- pthread_t self = pthread_self();
- int n;
+ pthread_t self = __pthread_self();
+ 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);
}
void __do_cleanup_push(struct __ptcb *cb)
{
- struct pthread *self = pthread_self();
+ if (!libc.has_thread_pointer) return;
+ struct pthread *self = __pthread_self();
cb->__next = self->cancelbuf;
self->cancelbuf = cb;
}
void __do_cleanup_pop(struct __ptcb *cb)
{
+ if (!libc.has_thread_pointer) return;
__pthread_self()->cancelbuf = cb->__next;
}
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,
/* pthread_key_create.c overrides this */
static const size_t dummy = 0;
weak_alias(dummy, __pthread_tsd_size);
+static void *const dummy_tsd[1] = { 0 };
+weak_alias(dummy_tsd, __pthread_tsd_main);
static FILE *const dummy_file = 0;
weak_alias(dummy_file, __stdin_used);
{
int ret;
size_t size, guard;
- struct pthread *self = pthread_self(), *new;
+ struct pthread *self, *new;
unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
- unsigned flags = 0x7d8f00;
+ unsigned flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND
+ | CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS
+ | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED;
int do_sched = 0;
pthread_attr_t attr = {0};
- if (!self) return ENOSYS;
+ if (!libc.can_do_threads) return ENOSYS;
+ self = __pthread_self();
if (!libc.threaded) {
for (FILE *f=libc.ofl_head; f; f=f->next)
init_file_lock(f);
init_file_lock(__stdin_used);
init_file_lock(__stdout_used);
init_file_lock(__stderr_used);
+ __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, _NSIG/8);
+ self->tsd = (void **)__pthread_tsd_main;
libc.threaded = 1;
}
if (attrp) attr = *attrp;
size_t need = libc.tls_size + __pthread_tsd_size;
size = attr._a_stacksize + DEFAULT_STACK_SIZE;
stack = (void *)(attr._a_stackaddr & -16);
- stack_limit = attr._a_stackaddr - size;
+ 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. */
new->tsd = (void *)tsd;
if (attr._a_detach) {
new->detached = 1;
- flags -= 0x200000;
+ flags -= CLONE_CHILD_CLEARTID;
}
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) {
projects / musl / blobdiff