Avoid global thread list in WASM (cherry-picked from bbc1faa)

Author: kleisauke

system/lib/libc/musl/src/thread/pthread_key_create.c

@@ -17,12 +17,14 @@ static void nodtor(void *dummy)
 {
 }
 
+#ifndef __EMSCRIPTEN__ // XXX Emscripten: There's no global thread list in WASM
 static void dummy_0(void)
 {
 }
 
 weak_alias(dummy_0, __tl_lock);
 weak_alias(dummy_0, __tl_unlock);
+#endif
 
 int __pthread_key_create(pthread_key_t *k, void (*dtor)(void *))
 {
@@ -52,15 +54,23 @@ int __pthread_key_create(pthread_key_t *k, void (*dtor)(void *))
 int __pthread_key_delete(pthread_key_t k)
 {
 	sigset_t set;
+#ifdef __EMSCRIPTEN__ // XXX Emscripten: There's no global thread list in WASM
+	pthread_t self = __pthread_self();
+#else
 	pthread_t self = __pthread_self(), td=self;
+#endif
 
 	__block_app_sigs(&set);
 	__pthread_rwlock_wrlock(&key_lock);
 
+#ifdef __EMSCRIPTEN__ // XXX Emscripten: There's no global thread list in WASM
+	self->tsd[k] = 0;
+#else
 	__tl_lock();
 	do td->tsd[k] = 0;
 	while ((td=td->next)!=self);
 	__tl_unlock();
+#endif
 
 	keys[k] = 0;
 

system/lib/pthread/library_pthread.c

@@ -843,6 +843,5 @@ void __emscripten_init_main_thread(void) {
   // tid is always non-zero.
   __main_pthread.tid = getpid();
   __main_pthread.locale = &libc.global_locale;
-  __main_pthread.next = __main_pthread.prev = &__main_pthread;
   __main_pthread.tsd = (void **)__pthread_tsd_main;
 }

system/lib/pthread/pthread_create.c

@@ -68,31 +68,6 @@ static long dummy_getpid() {
 }
 weak_alias(dummy_getpid, __syscall_getpid);
 
-static int tl_lock_count;
-static int tl_lock_waiters;
-
-volatile int __thread_list_lock;
-
-void __tl_lock(void) {
-  int tid = __pthread_self()->tid;
-  int val = __thread_list_lock;
-  if (val == tid) {
-    tl_lock_count++;
-    return;
-  }
-  while ((val = a_cas(&__thread_list_lock, 0, tid)))
-    __wait(&__thread_list_lock, &tl_lock_waiters, val, 0);
-}
-
-void __tl_unlock(void) {
-  if (tl_lock_count) {
-    tl_lock_count--;
-    return;
-  }
-  a_store(&__thread_list_lock, 0);
-  if (tl_lock_waiters) __wake(&__thread_list_lock, 1, 0);
-}
-
 int __pthread_create(pthread_t* restrict res,
                      const pthread_attr_t* restrict attrp,
                      void* (*entry)(void*),
@@ -120,8 +95,6 @@ int __pthread_create(pthread_t* restrict res,
     libc.threaded = 1;
   }
 
-  struct pthread *self = __pthread_self();
-
   // Allocate thread block (pthread_t structure).
   struct pthread *new = malloc(sizeof(struct pthread));
   // zero-initialize thread structure.
@@ -141,23 +114,8 @@ int __pthread_create(pthread_t* restrict res,
   new->tsd = malloc(PTHREAD_KEYS_MAX * sizeof(void*));
   memset(new->tsd, 0, PTHREAD_KEYS_MAX * sizeof(void*));
 
-  //printf("start __pthread_create: %p\n", self);
-  int rtn = __pthread_create_js(new, attrp, entry, arg);
-  if (rtn != 0)
-    return rtn;
-
-  __tl_lock();
-
-  new->next = self->next;
-  new->prev = self;
-  new->next->prev = new;
-  new->prev->next = new;
-
-  __tl_unlock();
-
   *res = new;
-  //printf("done __pthread_create self=%p next=%p prev=%p new=%p\n", self, self->next, self->prev, new);
-  return 0;
+  return __pthread_create_js(new, attrp, entry, arg);
 }
 
 static void free_tls_data() {
@@ -186,14 +144,6 @@ void _emscripten_thread_exit(void* result) {
 
   free_tls_data();
 
-  __tl_lock();
-
-  self->next->prev = self->prev;
-  self->prev->next = self->next;
-  self->prev = self->next = self;
-
-  __tl_unlock();
-
   if (self == emscripten_main_browser_thread_id()) {
     exit(0);
     return;

tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.funcs

@@ -10,8 +10,6 @@ $__pthread_self_internal
 $__pthread_setcancelstate
 $__stdio_write
 $__timedwait
-$__tl_lock
-$__tl_unlock
 $__wasi_syscall_ret
 $__wasm_call_ctors
 $__wasm_init_memory

tests/other/metadce/minimal_main_Oz_USE_PTHREADS_PROXY_TO_PTHREAD.size

@@ -1 +1 @@
-17993
+17573