factor cancellation cleanup push/pop out of futex __timedwait function

previously, the __timedwait function was optionally a cancellation
point depending on whether it was passed a pointer to a cleaup
function and context to register. as of now, only one caller actually
used such a cleanup function (and it may face removal soon); most
callers either passed a null pointer to disable cancellation or a
dummy cleanup function.

now, __timedwait is never a cancellation point, and __timedwait_cp is
the cancellable version. this makes the intent of the calling code
more obvious and avoids ugly dummy functions and long argument lists.

src/aio/aio_suspend.c

@@ -61,7 +61,7 @@ int aio_suspend(const struct aiocb *const cbs[], int cnt, const struct timespec
 			break;
 		}
 
-		ret = __timedwait(pfut, expect, CLOCK_MONOTONIC, ts?&at:0, 0, 0, 1);
+		ret = __timedwait(pfut, expect, CLOCK_MONOTONIC, ts?&at:0, 1);
 
 		if (ret) {
 			errno = ret==ETIMEDOUT ? EAGAIN : ret;

src/internal/pthread_impl.h

@@ -107,7 +107,8 @@ int __libc_sigprocmask(int, const sigset_t *, sigset_t *);
 void __lock(volatile int *);
 void __unmapself(void *, size_t);
 
-int __timedwait(volatile int *, int, clockid_t, const struct timespec *, void (*)(void *), void *, int);
+int __timedwait(volatile int *, int, clockid_t, const struct timespec *, int);
+int __timedwait_cp(volatile int *, int, clockid_t, const struct timespec *, int);
 void __wait(volatile int *, volatile int *, int, int);
 static inline void __wake(volatile void *addr, int cnt, int priv)
 {

src/thread/__timedwait.c

@@ -3,15 +3,15 @@
 #include <errno.h>
 #include "futex.h"
 #include "syscall.h"
+#include "pthread_impl.h"
 
 int __pthread_setcancelstate(int, int *);
 int __clock_gettime(clockid_t, struct timespec *);
 
-int __timedwait(volatile int *addr, int val,
-	clockid_t clk, const struct timespec *at,
-	void (*cleanup)(void *), void *arg, int priv)
+int __timedwait_cp(volatile int *addr, int val,
+	clockid_t clk, const struct timespec *at, int priv)
 {
-	int r, cs;
+	int r;
 	struct timespec to, *top=0;
 
 	if (priv) priv = 128;
@@ -28,15 +28,19 @@ int __timedwait(volatile int *addr, int val,
 		top = &to;
 	}
 
-	if (!cleanup) __pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
-	pthread_cleanup_push(cleanup, arg);
-
 	r = -__syscall_cp(SYS_futex, addr, FUTEX_WAIT|priv, val, top);
 	if (r == ENOSYS) r = -__syscall_cp(SYS_futex, addr, FUTEX_WAIT, val, top);
 	if (r != EINTR && r != ETIMEDOUT && r != ECANCELED) r = 0;
 
-	pthread_cleanup_pop(0);
-	if (!cleanup) __pthread_setcancelstate(cs, 0);
+	return r;
+}
 
+int __timedwait(volatile int *addr, int val,
+	clockid_t clk, const struct timespec *at, int priv)
+{
+	int cs, r;
+	__pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
+	r = __timedwait_cp(addr, val, clk, at, priv);
+	__pthread_setcancelstate(cs, 0);
 	return r;
 }

src/thread/pthread_cond_timedwait.c

@@ -64,10 +64,6 @@ enum {
 	LEAVING,
 };
 
-static void dummy(void *arg)
-{
-}
-
 int __pthread_cond_timedwait(pthread_cond_t *restrict c, pthread_mutex_t *restrict m, const struct timespec *restrict ts)
 {
 	struct waiter node = { 0 };
@@ -104,7 +100,7 @@ int __pthread_cond_timedwait(pthread_cond_t *restrict c, pthread_mutex_t *restri
 
 	__pthread_setcancelstate(PTHREAD_CANCEL_MASKED, &cs);
 
-	do e = __timedwait(fut, seq, clock, ts, dummy, 0, !shared);
+	do e = __timedwait_cp(fut, seq, clock, ts, !shared);
 	while (*fut==seq && (!e || e==EINTR));
 	if (e == EINTR) e = 0;
 

src/thread/pthread_join.c

@@ -3,15 +3,11 @@
 
 int __munmap(void *, size_t);
 
-static void dummy(void *p)
-{
-}
-
 int __pthread_join(pthread_t t, void **res)
 {
 	int tmp;
 	pthread_testcancel();
-	while ((tmp = t->tid)) __timedwait(&t->tid, tmp, 0, 0, dummy, 0, 0);
+	while ((tmp = t->tid)) __timedwait_cp(&t->tid, tmp, 0, 0, 0);
 	if (res) *res = t->result;
 	if (t->map_base) __munmap(t->map_base, t->map_size);
 	return 0;

src/thread/pthread_mutex_timedlock.c

@@ -24,7 +24,7 @@ int __pthread_mutex_timedlock(pthread_mutex_t *restrict m, const struct timespec
 		a_inc(&m->_m_waiters);
 		t = r | 0x80000000;
 		a_cas(&m->_m_lock, r, t);
-		r = __timedwait(&m->_m_lock, t, CLOCK_REALTIME, at, 0, 0, priv);
+		r = __timedwait(&m->_m_lock, t, CLOCK_REALTIME, at, priv);
 		a_dec(&m->_m_waiters);
 		if (r && r != EINTR) break;
 	}

src/thread/pthread_rwlock_timedrdlock.c

@@ -15,7 +15,7 @@ int pthread_rwlock_timedrdlock(pthread_rwlock_t *restrict rw, const struct times
 		t = r | 0x80000000;
 		a_inc(&rw->_rw_waiters);
 		a_cas(&rw->_rw_lock, r, t);
-		r = __timedwait(&rw->_rw_lock, t, CLOCK_REALTIME, at, 0, 0, rw->_rw_shared^128);
+		r = __timedwait(&rw->_rw_lock, t, CLOCK_REALTIME, at, rw->_rw_shared^128);
 		a_dec(&rw->_rw_waiters);
 		if (r && r != EINTR) return r;
 	}

src/thread/pthread_rwlock_timedwrlock.c

@@ -15,7 +15,7 @@ int pthread_rwlock_timedwrlock(pthread_rwlock_t *restrict rw, const struct times
 		t = r | 0x80000000;
 		a_inc(&rw->_rw_waiters);
 		a_cas(&rw->_rw_lock, r, t);
-		r = __timedwait(&rw->_rw_lock, t, CLOCK_REALTIME, at, 0, 0, rw->_rw_shared^128);
+		r = __timedwait(&rw->_rw_lock, t, CLOCK_REALTIME, at, rw->_rw_shared^128);
 		a_dec(&rw->_rw_waiters);
 		if (r && r != EINTR) return r;
 	}

src/thread/sem_timedwait.c

@@ -19,8 +19,9 @@ int sem_timedwait(sem_t *restrict sem, const struct timespec *restrict at)
 		int r;
 		a_inc(sem->__val+1);
 		a_cas(sem->__val, 0, -1);
-		r = __timedwait(sem->__val, -1, CLOCK_REALTIME, at, cleanup, sem->__val+1, sem->__val[2]);
-		a_dec(sem->__val+1);
+		pthread_cleanup_push(cleanup, sem->__val+1);
+		r = __timedwait_cp(sem->__val, -1, CLOCK_REALTIME, at, sem->__val[2]);
+		pthread_cleanup_pop(1);
 		if (r && r != EINTR) {
 			errno = r;
 			return -1;