make thread killlock async-signal-safe for pthread_kill

pthread_kill is required to be AS-safe. that requirement can't be met
if the target thread's killlock can be taken in contexts where
application-installed signal handlers can run.

block signals around use of this lock in all pthread_* functions which
target a tid, and reorder blocking/unblocking of signals in
pthread_exit so that they're blocked whenever the killlock is held.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/thread/pthread_setschedparam.c b/src/thread/pthread_setschedparam.c
index 038d13d8..76d4d45a 100644
--- a/src/thread/pthread_setschedparam.c
+++ b/src/thread/pthread_setschedparam.c
@@ -4,8 +4,11 @@
 int pthread_setschedparam(pthread_t t, int policy, const struct sched_param *param)
 {
 	int r;
+	sigset_t set;
+	__block_app_sigs(&set);
 	LOCK(t->killlock);
 	r = !t->tid ? ESRCH : -__syscall(SYS_sched_setscheduler, t->tid, policy, param);
 	UNLOCK(t->killlock);
+	__restore_sigs(&set);
 	return r;
 }