MFC r258499:

Fix for the spurious signal handler call with zero signo in the threaded
process.

Approved by:	re (hrs)

2 files changed, 10 insertions, 2 deletions

diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_private.h
index 83a02b5..c6651cd 100644
--- a/lib/libthr/thread/thr_private.h
+++ b/lib/libthr/thread/thr_private.h
@@ -433,6 +433,9 @@ struct pthread {
 	/* the sigaction should be used for deferred signal. */
 	struct sigaction	deferred_sigact;
 
+	/* deferred signal delivery is performed, do not reenter. */
+	int			deferred_run;
+
 	/* Force new thread to exit. */
 	int			force_exit;
 
diff --git a/lib/libthr/thread/thr_sig.c b/lib/libthr/thread/thr_sig.c
index 415ddb0..57c9406 100644
--- a/lib/libthr/thread/thr_sig.c
+++ b/lib/libthr/thread/thr_sig.c
@@ -162,6 +162,7 @@ thr_sighandler(int sig, siginfo_t *info, void *_ucp)
 	act = _thr_sigact[sig-1].sigact;
 	_thr_rwl_unlock(&_thr_sigact[sig-1].lock);
 	errno = err;
+	curthread->deferred_run = 0;
 
 	/*
 	 * if a thread is in critical region, for example it holds low level locks,
@@ -320,14 +321,18 @@ check_deferred_signal(struct pthread *curthread)
 	siginfo_t info;
 	int uc_len;
 
-	if (__predict_true(curthread->deferred_siginfo.si_signo == 0))
+	if (__predict_true(curthread->deferred_siginfo.si_signo == 0 ||
+	    curthread->deferred_run))
 		return;
 
+	curthread->deferred_run = 1;
 	uc_len = __getcontextx_size();
 	uc = alloca(uc_len);
 	getcontext(uc);
-	if (curthread->deferred_siginfo.si_signo == 0)
+	if (curthread->deferred_siginfo.si_signo == 0) {
+		curthread->deferred_run = 0;
 		return;
+	}
 	__fillcontextx2((char *)uc);
 	act = curthread->deferred_sigact;
 	uc->uc_sigmask = curthread->deferred_sigmask;