If a new thread is created, it inherits current thread's signal masks,

however if current thread is executing cancellation handler, signal
SIGCANCEL may have already been blocked, this is unexpected, unblock the
signal in new thread if this happens.

MFC after: 1 week

3 files changed, 24 insertions, 1 deletions

diff --git a/lib/libthr/thread/thr_create.c b/lib/libthr/thread/thr_create.c
index 03f0584..3bfd3b3 100644
--- a/lib/libthr/thread/thr_create.c
+++ b/lib/libthr/thread/thr_create.c
@@ -123,6 +123,11 @@ _pthread_create(pthread_t * thread, const pthread_attr_t * attr,
 	if (new_thread->attr.flags & PTHREAD_CREATE_DETACHED)
 		new_thread->tlflags |= TLFLAGS_DETACHED;
 
+	if (curthread->in_sigcancel_handler)
+		new_thread->unblock_sigcancel = 1;
+	else
+		new_thread->unblock_sigcancel = 0;
+
 	/* Add the new thread. */
 	new_thread->refcount = 1;
 	_thr_link(curthread, new_thread);
@@ -172,8 +177,10 @@ _pthread_create(pthread_t * thread, const pthread_attr_t * attr,
 			ret = EAGAIN;
 	}
 
-	if (create_suspended)
+	if (create_suspended) {
 		__sys_sigprocmask(SIG_SETMASK, &oset, NULL);
+		SIGDELSET(oset, SIGCANCEL);
+	}
 
 	if (ret != 0) {
 		if (!locked)
@@ -217,6 +224,14 @@ create_stack(struct pthread_attr *pattr)
 static void
 thread_start(struct pthread *curthread)
 {
+	if (curthread->unblock_sigcancel) {
+		sigset_t set;
+
+		SIGEMPTYSET(set);
+		SIGADDSET(set, SIGCANCEL);
+		sigprocmask(SIG_UNBLOCK, &set, NULL);
+	}
+
 	if (curthread->attr.suspend == THR_CREATE_SUSPENDED) {
 		sigset_t set = curthread->sigmask;
 
diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_private.h
index 4db3b7a..ff9f52b 100644
--- a/lib/libthr/thread/thr_private.h
+++ b/lib/libthr/thread/thr_private.h
@@ -378,6 +378,12 @@ struct pthread {
 	/* Thread temporary signal mask. */
 	sigset_t		sigmask;
 
+	/* Thread is in SIGCANCEL handler. */
+	int			in_sigcancel_handler;
+
+	/* New thread should unblock SIGCANCEL. */
+	int			unblock_sigcancel;
+
 	/* Thread state: */
 	enum pthread_state 	state;
 
diff --git a/lib/libthr/thread/thr_sig.c b/lib/libthr/thread/thr_sig.c
index 6da4b90..c8ebc24 100644
--- a/lib/libthr/thread/thr_sig.c
+++ b/lib/libthr/thread/thr_sig.c
@@ -69,7 +69,9 @@ sigcancel_handler(int sig __unused,
 
 	if (curthread->cancel_defer && curthread->cancel_pending)
 		thr_wake(curthread->tid);
+	curthread->in_sigcancel_handler = 1;
 	_thr_ast(curthread);
+	curthread->in_sigcancel_handler = 0;
 }
 
 void