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Disable pthread_exit for now
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The current wasi-threads has no thread-exit functionality.
Thus it isn't straightforward to implement pthread_exit
without leaking thread context. This commit simply disables
pthread_exit for now.

Also, instead of abusing `wasi_proc_exit` for thread exit,
make let `wasi_thread_start` return.

Note: `wasi_proc_exit` is supposed to terminate all threads
in the "process", not only the calling thread.

Note: Depending on the conclusion of the discussion about
`wasi_thread_exit`, we might revisit this change later.

References:
WebAssembly/wasi-threads#7
WebAssembly/wasi-threads#17
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yamt committed Dec 19, 2022
1 parent fb9c922 commit e8bc346
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Showing 4 changed files with 12 additions and 5 deletions.
2 changes: 0 additions & 2 deletions expected/wasm32-wasi-pthread/defined-symbols.txt
Original file line number Diff line number Diff line change
Expand Up @@ -193,7 +193,6 @@ __progname
__progname_full
__pthread_cond_timedwait
__pthread_create
__pthread_exit
__pthread_join
__pthread_key_create
__pthread_key_delete
Expand Down Expand Up @@ -1002,7 +1001,6 @@ pthread_condattr_setclock
pthread_condattr_setpshared
pthread_create
pthread_detach
pthread_exit
pthread_getspecific
pthread_join
pthread_key_create
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2 changes: 2 additions & 0 deletions libc-top-half/musl/include/pthread.h
Original file line number Diff line number Diff line change
Expand Up @@ -85,7 +85,9 @@ extern "C" {

int pthread_create(pthread_t *__restrict, const pthread_attr_t *__restrict, void *(*)(void *), void *__restrict);
int pthread_detach(pthread_t);
#ifdef __wasilibc_unmodified_upstream
_Noreturn void pthread_exit(void *);
#endif
int pthread_join(pthread_t, void **);

#ifdef __GNUC__
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2 changes: 2 additions & 0 deletions libc-top-half/musl/src/include/pthread.h
Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,9 @@ hidden int __pthread_once(pthread_once_t *, void (*)(void));
hidden void __pthread_testcancel(void);
hidden int __pthread_setcancelstate(int, int *);
hidden int __pthread_create(pthread_t *restrict, const pthread_attr_t *restrict, void *(*)(void *), void *restrict);
#ifdef __wasilibc_unmodified_upstream
hidden _Noreturn void __pthread_exit(void *);
#endif
hidden int __pthread_join(pthread_t, void **);
hidden int __pthread_mutex_lock(pthread_mutex_t *);
hidden int __pthread_mutex_trylock(pthread_mutex_t *);
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11 changes: 8 additions & 3 deletions libc-top-half/musl/src/thread/pthread_create.c
Original file line number Diff line number Diff line change
Expand Up @@ -60,7 +60,11 @@ void __tl_sync(pthread_t td)
if (tl_lock_waiters) __wake(&__thread_list_lock, 1, 0);
}

#ifdef __wasilibc_unmodified_upstream
_Noreturn void __pthread_exit(void *result)
#else
static void __pthread_exit(void *result)
#endif
{
pthread_t self = __pthread_self();
sigset_t set;
Expand Down Expand Up @@ -191,7 +195,7 @@ _Noreturn void __pthread_exit(void *result)
__tl_unlock();
free(self->map_base);
// Can't use `exit()` here, because it is too high level
for (;;) __wasi_proc_exit(0);
return;
}
#endif

Expand All @@ -212,7 +216,6 @@ _Noreturn void __pthread_exit(void *result)
// do it manually here
__tl_unlock();
// Can't use `exit()` here, because it is too high level
for (;;) __wasi_proc_exit(0);
#endif
}

Expand Down Expand Up @@ -272,7 +275,7 @@ static int start_c11(void *p)
}
#else
__attribute__((export_name("wasi_thread_start")))
_Noreturn void wasi_thread_start(int tid, void *p)
void wasi_thread_start(int tid, void *p)
{
struct start_args *args = p;
__asm__(".globaltype __tls_base, i32\n"
Expand Down Expand Up @@ -560,5 +563,7 @@ int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict att
return EAGAIN;
}

#ifdef __wasilibc_unmodified_upstream
weak_alias(__pthread_exit, pthread_exit);
#endif
weak_alias(__pthread_create, pthread_create);

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