1 files changed, 56 insertions, 43 deletions

diff --git a/src/time/timer_create.c b/src/time/timer_create.c
index d9fbaee5..cc6c2236 100644
--- a/src/time/timer_create.c
+++ b/src/time/timer_create.c
@@ -1,6 +1,9 @@
 #include <time.h>
 #include <setjmp.h>
+#include <limits.h>
+#include <semaphore.h>
 #include "pthread_impl.h"
+#include "atomic.h"
 
 struct ksigevent {
 	union sigval sigev_value;
@@ -10,7 +13,7 @@ struct ksigevent {
 };
 
 struct start_args {
-	pthread_barrier_t b;
+	sem_t sem1, sem2;
 	struct sigevent *sev;
 };
 
@@ -19,66 +22,60 @@ static void dummy_0()
 }
 weak_alias(dummy_0, __pthread_tsd_run_dtors);
 
+static void timer_handler(int sig, siginfo_t *si, void *ctx)
+{
+}
+
 static void cleanup_fromsig(void *p)
 {
 	pthread_t self = __pthread_self();
 	__pthread_tsd_run_dtors();
+	__block_app_sigs(0);
+	__syscall(SYS_rt_sigprocmask, SIG_BLOCK, SIGTIMER_SET, 0, _NSIG/8);
 	self->cancel = 0;
 	self->cancelbuf = 0;
 	self->canceldisable = 0;
 	self->cancelasync = 0;
-	self->unblock_cancel = 0;
 	__reset_tls();
 	longjmp(p, 1);
 }
 
-static void timer_handler(int sig, siginfo_t *si, void *ctx)
-{
-	pthread_t self = __pthread_self();
-	jmp_buf jb;
-	void (*notify)(union sigval) = (void (*)(union sigval))self->start;
-	union sigval val = { .sival_ptr = self->start_arg };
-
-	if (!setjmp(jb) && si->si_code == SI_TIMER) {
-		pthread_cleanup_push(cleanup_fromsig, jb);
-		notify(val);
-		pthread_cleanup_pop(1);
-	}
-}
-
-static void install_handler()
-{
-	struct sigaction sa = {
-		.sa_sigaction = timer_handler,
-		.sa_flags = SA_SIGINFO | SA_RESTART
-	};
-	__libc_sigaction(SIGTIMER, &sa, 0);
-}
-
 static void *start(void *arg)
 {
 	pthread_t self = __pthread_self();
 	struct start_args *args = arg;
-	int id;
+	jmp_buf jb;
+
+	void (*notify)(union sigval) = args->sev->sigev_notify_function;
+	union sigval val = args->sev->sigev_value;
 
-	/* Reuse no-longer-needed thread structure fields to avoid
-	 * needing the timer address in the signal handler. */
-	self->start = (void *(*)(void *))args->sev->sigev_notify_function;
-	self->start_arg = args->sev->sigev_value.sival_ptr;
+	/* The two-way semaphore synchronization ensures that we see
+	 * self->cancel set by the parent if timer creation failed or
+	 * self->timer_id if it succeeded, and informs the parent that
+	 * we are done accessing the arguments so that the parent can
+	 * proceed past their block lifetime. */
+	while (sem_wait(&args->sem1));
+	sem_post(&args->sem2);
 
-	pthread_barrier_wait(&args->b);
-	if ((id = self->timer_id) >= 0) {
-		__syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
-			SIGTIMER_SET, 0, _NSIG/8);
-		__wait(&self->timer_id, 0, id, 1);
-		__syscall(SYS_timer_delete, id);
+	if (self->cancel)
+		return 0;
+	for (;;) {
+		siginfo_t si;
+		while (sigwaitinfo(SIGTIMER_SET, &si) < 0);
+		if (si.si_code == SI_TIMER && !setjmp(jb)) {
+			pthread_cleanup_push(cleanup_fromsig, jb);
+			notify(val);
+			pthread_cleanup_pop(1);
+		}
+		if (self->timer_id < 0) break;
 	}
+	__syscall(SYS_timer_delete, self->timer_id & INT_MAX);
 	return 0;
 }
 
 int timer_create(clockid_t clk, struct sigevent *restrict evp, timer_t *restrict res)
 {
-	static pthread_once_t once = PTHREAD_ONCE_INIT;
+	static volatile int init = 0;
 	pthread_t td;
 	pthread_attr_t attr;
 	int r;
@@ -90,11 +87,15 @@ int timer_create(clockid_t clk, struct sigevent *restrict evp, timer_t *restrict
 	switch (evp ? evp->sigev_notify : SIGEV_SIGNAL) {
 	case SIGEV_NONE:
 	case SIGEV_SIGNAL:
+	case SIGEV_THREAD_ID:
 		if (evp) {
 			ksev.sigev_value = evp->sigev_value;
 			ksev.sigev_signo = evp->sigev_signo;
 			ksev.sigev_notify = evp->sigev_notify;
-			ksev.sigev_tid = 0;
+			if (evp->sigev_notify == SIGEV_THREAD_ID)
+				ksev.sigev_tid = evp->sigev_notify_thread_id;
+			else
+				ksev.sigev_tid = 0;
 			ksevp = &ksev;
 		}
 		if (syscall(SYS_timer_create, clk, ksevp, &timerid) < 0)
@@ -102,16 +103,25 @@ int timer_create(clockid_t clk, struct sigevent *restrict evp, timer_t *restrict
 		*res = (void *)(intptr_t)timerid;
 		break;
 	case SIGEV_THREAD:
-		pthread_once(&once, install_handler);
+		if (!init) {
+			struct sigaction sa = {
+				.sa_sigaction = timer_handler,
+				.sa_flags = SA_SIGINFO | SA_RESTART
+			};
+			__libc_sigaction(SIGTIMER, &sa, 0);
+			a_store(&init, 1);
+		}
 		if (evp->sigev_notify_attributes)
 			attr = *evp->sigev_notify_attributes;
 		else
 			pthread_attr_init(&attr);
 		pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
-		pthread_barrier_init(&args.b, 0, 2);
+		sem_init(&args.sem1, 0, 0);
+		sem_init(&args.sem2, 0, 0);
 		args.sev = evp;
 
 		__block_app_sigs(&set);
+		__syscall(SYS_rt_sigprocmask, SIG_BLOCK, SIGTIMER_SET, 0, _NSIG/8);
 		r = pthread_create(&td, &attr, start, &args);
 		__restore_sigs(&set);
 		if (r) {
@@ -121,12 +131,15 @@ int timer_create(clockid_t clk, struct sigevent *restrict evp, timer_t *restrict
 
 		ksev.sigev_value.sival_ptr = 0;
 		ksev.sigev_signo = SIGTIMER;
-		ksev.sigev_notify = 4; /* SIGEV_THREAD_ID */
+		ksev.sigev_notify = SIGEV_THREAD_ID;
 		ksev.sigev_tid = td->tid;
-		if (syscall(SYS_timer_create, clk, &ksev, &timerid) < 0)
+		if (syscall(SYS_timer_create, clk, &ksev, &timerid) < 0) {
 			timerid = -1;
+			td->cancel = 1;
+		}
 		td->timer_id = timerid;
-		pthread_barrier_wait(&args.b);
+		sem_post(&args.sem1);
+		while (sem_wait(&args.sem2));
 		if (timerid < 0) return -1;
 		*res = (void *)(INTPTR_MIN | (uintptr_t)td>>1);
 		break;