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Make futexes cancellable by pthreads

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This commit is contained in:
Justine Tunney 2022-11-04 18:19:05 -07:00
parent 2278327eba
commit 022536cab6
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GPG key ID: BE714B4575D6E328
101 changed files with 627 additions and 391 deletions
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21
libc/thread/pthread_cancel.c
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@ -24,6 +24,7 @@
#include "libc/calls/ucontext.h"
#include "libc/errno.h"
#include "libc/intrin/atomic.h"
#include "libc/intrin/kprintf.h"
#include "libc/runtime/runtime.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/sa.h"
@ -85,12 +86,12 @@ static void ListenForSigCancel(void) {
* `writev`, `pwrite`, `pwritev`, `accept`, `connect`, `recvmsg`,
* `sendmsg`, `recv`, `send`, `tcdrain`, `clock_nanosleep`, `fsync`,
* `fdatasync`, `fcntl(F_SETLKW)`, `epoll`, `sigsuspend`, `msync`,
* `wait4`, `getrandom`, `pthread_cond_timedwait` are most cancellation
* points, plus many userspace libraries that call the above functions,
* unless they're using pthread_setcancelstate() to temporarily disable
* the cancellation mechanism. Some userspace functions, e.g. system()
* and popen() will eagerly call pthread_testcancel_np() to help avoid
* the potential for resource leaks later on.
* `wait4`, `getrandom`, `pthread_cond_timedwait`, and `sem_timedwait`
* are most cancellation points, plus many userspace libraries that call
* the above functions, unless they're using pthread_setcancelstate() to
* temporarily disable the cancellation mechanism. Some userspace
* functions, e.g. system() will eagerly call pthread_testcancel_np() to
* help avoid the potential for resource leaks later on.
*
* It's possible to put a thread in asynchronous cancellation mode using
* pthread_setcanceltype(), thus allowing a cancellation to occur at any
@ -110,7 +111,7 @@ static void ListenForSigCancel(void) {
* @return 0 on success, or errno on error
* @raise ESRCH if thread isn't alive
*/
int pthread_cancel(pthread_t thread) {
errno_t pthread_cancel(pthread_t thread) {
int e, rc, tid;
static bool once;
struct PosixThread *pt;
@ -124,9 +125,9 @@ int pthread_cancel(pthread_t thread) {
default:
break;
}
atomic_store_explicit(&pt->cancelled, 1, memory_order_release);
atomic_exchange_explicit(&pt->cancelled, 1, memory_order_release);
if (thread == __get_tls()->tib_pthread) {
if (!(pt->flags & PT_NOCANCEL) && (pt->flags & PT_ASYNC)) {
if (!(pt->flags & (PT_NOCANCEL | PT_MASKED)) && (pt->flags & PT_ASYNC)) {
pthread_exit(PTHREAD_CANCELED);
}
return 0;
@ -183,7 +184,7 @@ void pthread_testcancel(void) {
* @return 0 if not cancelled or cancellation is blocked or `ECANCELED`
* in masked mode when the calling thread has been cancelled
*/
int pthread_testcancel_np(void) {
errno_t pthread_testcancel_np(void) {
int rc;
struct PosixThread *pt;
if (!__tls_enabled) return 0;