Make POSIX threads improvements

- Ensure SIGTHR isn't blocked in newly created threads
- Use TIB rather than thread_local for thread atexits
- Make POSIX thread keys atomic within thread
- Don't bother logging prctl() to --strace
- Log thread destructor names to --strace

libc/thread/pthread_cancel.c

@@ -54,9 +54,8 @@ long _pthread_cancel_ack(void) {
     pthread_exit(PTHREAD_CANCELED);
   }
   pt->pt_flags |= PT_NOCANCEL;
-  if (IsOpenbsd()) {
+  if (IsOpenbsd())
     pt->pt_flags |= PT_OPENBSD_KLUDGE;
-  }
   return ecanceled();
 }
 
@@ -351,6 +350,7 @@ static errno_t _pthread_cancel_everyone(void) {
  * @param thread may be 0 to cancel all threads except self
  * @return 0 on success, or errno on error
  * @raise ESRCH if system thread wasn't alive or we lost a race
+ * @cancelationpoint
  */
 errno_t pthread_cancel(pthread_t thread) {
   struct PosixThread *arg;
@@ -401,6 +401,7 @@ void pthread_testcancel(void) {
  *
  * @return 0 if not cancelled or cancelation is blocked or `ECANCELED`
  *     in masked mode when the calling thread has been cancelled
+ * @cancelationpoint
  */
 errno_t pthread_testcancel_np(void) {
   struct PosixThread *pt;

libc/thread/pthread_create.c

@@ -117,6 +117,7 @@ static int PosixThread(void *arg, int tid) {
   }
   // set long jump handler so pthread_exit can bring control back here
   if (!setjmp(pt->pt_exiter)) {
+    sigdelset(&pt->pt_attr.__sigmask, SIGTHR);
     if (IsWindows()) {
       atomic_store_explicit(&__get_tls()->tib_sigmask, pt->pt_attr.__sigmask,
                             memory_order_release);

libc/thread/pthread_key_create.c

@@ -48,9 +48,9 @@ int pthread_key_create(pthread_key_t *key, pthread_key_dtor dtor) {
   if (!dtor)
     dtor = (pthread_key_dtor)-1;
   for (i = 0; i < PTHREAD_KEYS_MAX; ++i) {
-    if (!(expect = atomic_load_explicit(_pthread_key_dtor + i,
-                                        memory_order_acquire)) &&
-        atomic_compare_exchange_strong_explicit(_pthread_key_dtor + i, &expect,
+    if (!(expect = atomic_load_explicit(&_pthread_key_dtor[i],
+                                        memory_order_relaxed)) &&
+        atomic_compare_exchange_strong_explicit(&_pthread_key_dtor[i], &expect,
                                                 dtor, memory_order_release,
                                                 memory_order_relaxed)) {
       *key = i;

libc/thread/pthread_key_delete.c

@@ -16,7 +16,6 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/assert.h"
 #include "libc/errno.h"
 #include "libc/intrin/atomic.h"
 #include "libc/thread/posixthread.internal.h"
@@ -32,10 +31,12 @@
  *
  * @param key was created by pthread_key_create()
  * @return 0 on success, or errno on error
+ * @raise EINVAL if `key` is invalid
  */
 int pthread_key_delete(pthread_key_t k) {
-  unassert(0 <= k && k < PTHREAD_KEYS_MAX);
-  unassert(atomic_load_explicit(_pthread_key_dtor + k, memory_order_acquire));
-  atomic_store_explicit(_pthread_key_dtor + k, 0, memory_order_release);
+  if (!(0 <= k && k < PTHREAD_KEYS_MAX))
+    return EINVAL;  // corrupt key identifier
+  if (!atomic_exchange_explicit(&_pthread_key_dtor[k], 0, memory_order_acq_rel))
+    return EINVAL;  // delete called twice
   return 0;
 }

libc/thread/thread.h

@@ -1,7 +1,7 @@
 #ifndef COSMOPOLITAN_LIBC_THREAD_THREAD_H_
 #define COSMOPOLITAN_LIBC_THREAD_THREAD_H_
 
-#define PTHREAD_KEYS_MAX              48
+#define PTHREAD_KEYS_MAX              46
 #define PTHREAD_STACK_MIN             65536
 #define PTHREAD_DESTRUCTOR_ITERATIONS 4
 

libc/thread/tls.h

@@ -39,7 +39,8 @@ struct CosmoTib {
   uint32_t tib_sigstack_flags;
   _Atomic(int) tib_relock_maps;
   void *tib_nsync;
-  void *tib_keys[47];
+  void *tib_atexit;
+  _Atomic(void *) tib_keys[46];
 } __attribute__((__aligned__(64)));
 
 extern int __threaded;